Tag Archive | "generator"

Kit Review – JYE Tech FG085 DDS Function Generator

Introduction

There has been a lot of talk lately about inexpensive DDS (direct digital synthesis) function generators, and I always enjoy a kit – so it was time to check out the subject of this review. It’s the “FG085 miniDDS function generator” from JYE Tech. JYE is a small company in China that makes inexpensive test equipment kits, for example their capacitance meter (my first kit review!) and DSO. The capacitance meter was good, the DSO not so good – so let’s hope this is better than their last efforts.

Assembly

The instructions (AssemblyGuide_085G) are much better than previous efforts, and if you have bought the kit – read them. The kit arrives in a large zip-lock bag, with the following bundle of parts:

The AC adaptor is 100~240V in, 15V DC out. Everything is included with the kit including a short BNC to alligator clips lead for output. The PCBs are very good, with a nice solder mask and silk screen:

and back:

At this point we realise that most of the work is already done. There’s two microcontrollers ATmega48 and ATmega168- one for display and user-interface control, and the other for function generation. It takes only a few minutes to solder in the through-hole parts, headers and sockets:

… then you flip over the PCB and add the LCD:

… followed by the buttons and rotary encoder. From previous research this is the part that causes people a lot of trouble – so read carefully. There’s a lot of buttons – and if they aren’t inserted into the PCB correctly your life will become very difficult. The buttons must be inserted a certain way – they’re “polarised” – for example:

As you can see above, one side has a double-vertical line and the other side has a single. When you fit the buttons to the PCB – the side with the double-vertical must face the left-hand side of the PCB – the side with the DC socket. For example:

Furthermore, don’t be in a rush and put all the buttons in then try to solder them all at once.  Do them one at a time, and hold them tight to the PCB with some blu-tac or similar. If they don’t sit flush with the PCB the front panel won’t fit properly and the buttons will stick when in use. So exercise some patience, and you’ll be rewarded with an easy to use function generator. Rush them in and you’ll be very unhappy. I warned you! After fitting each button, test fit the front panel to check the alignment, for example:

Then you end up with nicely-aligned buttons:

… which all operate smoothly when the panel is fitted:

After the buttons comes the rotary encoder. Be very careful when fitting it to the PCB – the data legs are really weak, and bend without much effort. If you push in the encoder, be mindful of the legs not going through the holes and bending upwards. Furthermore, when soldering in the encoder note that you’re really close to an electrolytic – you don’t want to stab it with a hot iron:

The CP2012 chip in the image above is for the USB interface. More on that later. Now the next stage is the power-test. Connect DC power and turn it on – you should be greeted by a short copyright message followed by the operation display:

If you didn’t – remove the power and check your soldering –  including the capacitor polarities and look for bridges, especially around the USB socket. Now it’s time to fit the output BNC socket. For some reason only known to the designers, they have this poking out the front of the panel for the kit – however previous revisions have used a simple side-entry socket. Thus you need to do some modifications to the supplied socket. First, chop the tag from the sprocket washer:

… then remove the paper from the front panel:

Now solder a link to the washer in a vertical position:

… then fit the BNC socket to the panel, with the washer aligned as such:

Finally, align the top panel with the PCB so the BNC socket pin and washer link drop into the PCB and solder them in:

If you want to use the servo mode, solder three short wires that can attach to a servo form the three “output” pads between the BNC and USB socket.

Finally, screw in the panels and you’re finished!

Using the function generator

Operation is quite simple, and your first reference should be the manual (manual.pdf). The display defaults to normal function generator mode at power-up – where you can adjust the frequency, offset, amplitude and type of output – sine, square, triangle, ramp up, ramp down, staircase up and down:

The ranges for all functions is 0~10 khz, except for sine which can hit 200 kHz. You can enter higher frequencies, such as up to 250 kHz for sine – but the results aren’t so good.

Instead of filling this review with lots of screen dumps from an oscilloscope to demonstrate the output – I’ve made the following video where you can see various functions being displayed on a DSO:

You can also create signals to test servos, with adjustable pulse-width, amplitude and cycle times. However you’ll need to solder three wires onto the PCB (next to the BNC socket area) to attach to the servo.

According to the user manual and various retailers’ websites – the FG085 can generate frequency sweeping signals. These are signals that sweep from a start to as finish frequency over a period of time. However the firmware on the supplied unit is old and needs updating to enable this function. You can download the firmware in .hex file format from here. Then go and dig up an AVR programmer and avrdudeAt the time of writing we had some issues with the signature not being recognised when updating the firmware, and solidly bricked the FG085. Our fault – so when that’s sorted out we’ll update the review – stay tuned.

There is also a USB port on the side – after installing CP2102 drivers in Windows we could connect at 115200 bps with terminal, however all the FG085 returned was the firmware version number. Perhaps later on the designers will update the firmware to allow for PC control. Somehow I wouldn’t bank on it.

Oh – if you’re wondering what DDS is – click here!

Conclusion

It’s an interesting piece of equipment. Putting the firmware upgrade issues to one side, the FG085 does what it sets out to do. During testing it worked well, and we didn’t come across any obvious inaccuracies during use.  The price varies between US$43 and $50 – so for that money it’s  a good kit. Just take care during construction and you’ll be fine.

The function generator is available in kit form or assembled, with or without panels from China. The kit version with panels is also available from Sparkfun (KIT-11394) and their resellers. Full-sized images available on flickr. This kit was purchased and reviewed without notifying the supplier.

In the meanwhile have fun and keep checking into tronixstuff.com. Why not follow things on twitterGoogle+, subscribe  for email updates or RSS using the links on the right-hand column? And join our friendly Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

Posted in dds, ds2102, FG085, function generator, jyetech, kit review, KIT-11394, learning electronics, rigol, test equipmentComments (7)

Review – Agilent Infiniivision MSO-X 3024A Mixed Signal Oscilloscope

Hello Readers

In this article we examine the Agilent Technologies Infiniivision MSO-X 3024A Mixed Signal Oscilloscope. Please note that the review unit has the latest version 2.0 firmware (existing owners can upgrade with the free download).

Initial Impressions

Unlike smaller instruments the packaging is plain and non-descript, however the MSO is protected very well for global shipping and arrived in perfect condition. Inclusions will vary depending on the particular model, however all come with a calibration certificate, user guide on CD and a power lead.

image1

Four passive 300MHz probes are included with the MSO-X3024A:

image1a

Due to the constant upgrading of the firmware the lack of a printed user manual is no surprise. You can download the manual as well as the service, programming and  educational lab guides from the documents section of the product web page – which make good reading to get a feel for the unit.

Now for a tour around the unit. Coming from a smaller DSO or an analogue model, the first thing that strikes you is the display. 8.5” diagonal with 800×480 resolution:

image2

Unlike cheaper brands the larger screen is not extrapolating data from a smaller image – each pixel is separately used. The front panel is clean and uncluttered. Each button and knob feels solid and responsive, and if pressed and held down, a small help window appears with information about the item pressed. Note that each analogue channel has independent controls for vertical position and V/div sensitivity (the minimum sensitivity is 1mV/division). This saves a lot of time and possible confusion when working on time-sensitive applications.

Around the back we find the cooling van ventilation on the left, the IEC AC power socket on the bottom-right, manufacturing data and so on. The fan is just audible, however the noise from a desktop computer drowns it out. On the far right near the top are separate USB connections for device and host mode, and the external trigger input and output sockets. Apart from the trigger out signal the socket can also be set to give a 5V pulse on a mask test failure or the optional WaveGen sync pulse.

image3

Below this is a space for a Kensington lock cable, and the optional modules – the VGA/LAN adaptor or the GPIB bus module. On the right is my old faithful GW 20 MHz analogue CRO. Finally, there is a compartment on the top of the unit that can hold two probes comfortably, and four at a pinch:

image4

As the unit is can be considered a small computer, it takes time to boot up – just over thirty seconds. (The operating system is Windows CE version 6.0). The user-interface is quite simple considering the capability of the unit. The six soft-keys below the display are used well, and also can call a separate list of options under each button.

When such a list is presented, you can also use the “Push to select” knob on the right hand side of the display to select an option and lock in by pressing the knob in. Below the soft keys from left to right are: BNC output for the optional function generator, digital inputs for logic analyser, USB socket for saving data to a USB drive, probe points for calibration and demonstration use, and four probe sockets. Connections exist that can interface with optional Agilent active probes.

Specifications

This instrument falls within the range of Agilent’s new Infiniivision 3000-series oscilloscopes. The range begins with the DSO-X3012A with 100MHz bandwidth and two channels, through to the DSO-X3054A with 500 MHz bandwidth and four channels. Furthermore the range is extended with the MSO-X models that include a sixteen channel logic analyser.

Some of you will know there is also the Infiniivision 2000-series, and wonder why one would acquire a 3000-series. There are three excellent reasons for doing so:

  1. Waveform update rate is 50000 per second on a 2000, one million per second on a 3000;
  2. Memory depth on a 2000 is 100 kilopoints; 3000s have 2Mpts standard or 4Mpts optional;
  3. Eight vs. sixteen digital channels when specified as an MSO-X model.

For a full breakdown of specifications please download the Agilent data sheet located here.

Getting Started and general use

The process from cutting open the packaging to measuring a signal is quite simple – just plug it in, connect probes and go – however some probe compensation is required, which is explained quite well in the manual. There are strong tilting bales under the front side which can be used to face the unit upwards. At this point the unit is ready to go – you can start measuring by using the Auto Scale function and let the MSO-X3024A determine the appropriate display settings.

However there is no fun in that – the vertical scale can be manually adjusted between 1 mV and 50V per division, the horizontal between 2 nanoseconds and 50 seconds per division. These values can be selected rapidly or (by pressing the knob in) in a fine method for more precise values. If working with more than one channel, each can be labelled using a pre-set description or select a label from a list. One can also alter the display between X-Y, horizontal and roll modes.

Each channel has separate controls for coupling – DC/AC but no GND, as the earth point is shown on the LCD. Impedance can be 1M or 50 ohm. One can also limit bandwidth to 20MHz to remove high-frequency interference.

Capturing data is very easy, you can save images as .png or .bmp files in grey scale or colour , data in .csv form and so on. You can also assign popular functions to a “Quick Action” button – one press and it is done. For example I use this as a “save bitmap” button to send the screen image to the USB drive. If the optional LAN/VGA module is installed screens can be captured by the host computer via the network. Finally there is a very basic file explorer available to find files on the USB drive as well.

Waveforms can also be stored and used later on as references for other measurements. When reviewed they appear as an orange trace – for example R1:

rrr

The horizontal zoom mode activated using keys to the right of the horizontal control is very useful. Agilent call this “Mega Zoom” and it certainly works. Consider the following screen shot – the 32.768kHz square-wave from a Maxim DS1307 real-time clock is being analysed:

megazoom

The time base is 10uS per division – and using the zoom we can get down to two nanoseconds per division and investigate the ringing on fall of the square-wave. This is great for investigating complex signals over short periods. Awesome.

Capturing infrequent events is made simple by the combination of the one million waveforms per second sampling rate, and the use of infinite display persistence. In the following example a clock with very infrequent glitch is being sampled. By setting persistence to infinite, as soon as the infrequent glitch occurs it can be displayed and held on the screen. For example:

infreq

Triggering

There is a plethora of triggering options available. Standard modes include: edge, edge then edge, pulse-width (customisable), pattern trigger (for logic analyser – you can create your own patter of high, low, or doesn’t matter with comparison operators for duration), hex bus trigger, OR trigger, customisable rise/fall time trigger, nth edge burst trigger which allows  you to nth edge of a burst after an idle time, runt trigger on positive or negative pulse, setup and hold trigger, on video signals (PAL, PAL-M, NTSC, SECAM), and USB packets. Phew. Furthermore, if you have any of the optional decoding and analysis licenses, they include triggering on the matching signal type (see later).

Math modes

Performing math waveforms on analogue channels is done via a seperate Math button, and the operations available are addition, subtraction, multiplication, differentiation, integration, square root and FFT.

Waveform statistics

When the time comes to further analyse your measurement data, there area variety of measurements that can be taken, and they can be displayed individually, such as in the following:

stats1

or all in a summary screen:

allstats

Or you can manually use the cursors to determine information about any part of a wave form, for example:

cursors

Logic Analyser

Everything required is included with the MSO-X3024A for the sixteen channel logic analyser, including a very long dual-head probe cable:

lacables

as well as sixteen grabbers and some extension runs:

lacables2

Setup and use was surprisingly simple, just connect the probe cable head to ground, insert grabbers onto the ends of each channel wire, and connect to the signal pins to analyse. You can have all sixteen channels and the four analogue channels active at once, however when doing so the screen is quite busy. You can adjust the height  for each digital channel. Here we are measuring two analogue and eight digital channels:

msoinaction

As always there are many forms of customisation. Automatic scaling is available the same as analogue measurement. You can set the threshold levels for high and low, and presets exist for TTL, CMOS, ECL and your own custom levels. The cable is very well-built (made in the USA) and the socket on the MSO is a standard, very solid IDC connector. Thanks to the use of the IDC connector you could also make your own probes or extension cable for the analyser. Digital channels can also be combined and displayed as a data bus, with the data values shown in hexadecimal or binary – for example:

hexbus

binbus

Options

Both the 2000- and 3000-series Infiniivision units have a variety of options and upgrades available either at the time of purchase or later on. Agilent have been clever and installed all the software-based options in the unit – when required they are “unlocked” by entering a licence key given after purchase. Trial 14-day licenses are generally available if you want to test an option before purchase. You can also upgrade the bandwidth after purchase – for example if you started with a 100MHz a licence key purchase will upgrade you to 200MHz , or 350 to 500MHz. However if you wish to upgrade a 200MHz to 350/500, this needs to be performed at at Agilent service facility. Surprisingly the logic analyser upgrade that converts a DSO-X to an MSO-X is user-installable. For more information on the upgrade options and procedures please visit here.

Memory Upgrade (DSOX3MEMUP)

A simple yet useful option – it doubles the total memory depth to 4 Mpts interleaved.

LAN/VGA Module (DSOXLAN)

This options really opens up the MSO to the world (and is a lot of fun..) – it is inserted into the port at the rear of the unit:

lanvga1

VGA output is very simple – no setup required. Just plug in your monitor or projector and you’re ready to go -for example, with a 22″ LCD monitor:

monitorview

The educational benefits of the LAN/VGA module are immediately apparent – instead of having twenty classmates huddle around one MSO while the instructor demonstrates the unit, the display can be show on the classroom projector or a large monitor. The MSO display is still fully active while VGA output is used.

LAN connection via Ethernet was also very simple. The MSO can automatically connect to the network if you have a router with DHCP server. Otherwise you can use the Utility>I/O>LAN Settings function to enter various TCP/IP settings and view the MSO’s MAC address.

Once connected you can have complete control of the MSO over your network. Apart from saving screen shots:

remotesaveimage

There is a “simple” remote control interface that contains all the controls in a standard menu-driven environment:

simpleremotepanel

Or you can have a realistic reproduction of the entire MSO on your screen:

fullremotepanel

The full remote panel is completely identical – it’s “just like being there”. The ability to monitor your MSO from other areas could be very useful. For example using the mask testing in a QC area and watching the results in an office; or an educator monitoring students’ use of the MSO.

Furthermore you can view various data about the MSO, such as calibration date and temperature drift since calibration, installed options, serial number, etc. remotely via the web interface.

GPIB Module (DSOXGPIB)

This allows you to connect your MSO to an IEEE-488 communications bus for connection to less contemporary equipment.

Segmented Memory Option (DSOX3SGM)

This options allows you to capture infrequent multiple events over time. For example, you want to locate some 15 mS pulses that occur a few times over the space of an hour. All you need to do is set the triggering to pulse-width, specify the minimum/maximum pulse width to trigger from, then hit Acquire>Segmented, the number of segments to use and you’re off. When the pulses have been captured, you can return and analyse each one as normal. The unit records the start time and elapsed time for each segment, and you can still use zoom, etc., to examine the pulse. For example:

segment

Embedded Serial Triggering and Analysis (DSOX3EMBD)

Debugging I2C and SPI buses are no longer a chore with this option. For example with I2C just probe you SDA and SCK lines, adjust the thresholds in the menu option and you’re set. Apart from displaying the bytes of data below the actual waveform, there is a “Lister” which allows you to scroll back and forth along the captured data along with correlating times. In the following example a Maxim DS1307 RTC IC has been polled:

i2c_lister

The Lister details all – in the example we sent a zero to address 0x68, which caused the DS1307 to return the seven bytes of time and date data. This is an extremely useful option and is very useful when working with a range of sensors and other parts that use the I2C bus. The SPI bus analysis operates in exactly the same manner. Adding this option also allows triggering on I2C data as well.

FlexRay Triggering and Analysis (DSOX3FLEX)

The optional FlexRay measurement applications offer integrated FlexRay serial bus triggering, hardware-based decoding and analysis. The FlexRay measurement tools help you more efficiently debug and characterize your FlexRay physical layer network by having the ability to trigger on and time-correlate FlexRay communication with your physical layer signals. So if you are working on the ECU of your Rolls-Royce or new BMW 7-series, you can use an MSO that matches the quality of the vehicle under examination. Here is an example of the FlexRay being monitored in the lister:

flexray

RS232/UART Serial Decode and Trigger (COMP/MSOX3000-232)

This option allows RS232, 422, 485 and UART decoding and triggering, as well as the use of the Lister to analyse the data. For example:

uartdecode

Advanced Math (DSOX3ADVMATH)

This option adds more math functions to enhance your waveform analysis, including: divide, base-10 logarithm, natural logarithm and exponential.

CAN/LIN Triggering and Serial Decode (DSOX3AUTO)

Again, allows decoding of automotive CAN and LIN bus signals, and the use of the Lister. For example:

can_decode

lin_decode

Military Standard 1553 and ARINC429 Standards Serial Triggering and Decoding (DSOX3AERO)

The option exists for decoding and triggering of the above bus types. According to Agilent the Mil-STD 1553 serial bus is primarily used to interconnect avionics equipment in military aircraft and spacecraft(!). This bus is based on tri-level signaling (high, low, & idle) and requires dual-threshold triggering, which the 3000X supports. This bus is also implemented as a redundant multi-lane bus (dual-bus analysis), which is also supported by the 3000X.

The ARINC 429 serial bus is used to interconnect avionics equipment in civilian aircraft (Boeing & Airbus). This bus is also based on tri-level signaling (high, low, & null) and requires dual-threshold triggering, which the 3000X supports. Since ARINC 429 is a point-to-point bus, multi-lane analysis is also required to capture both send and receive data. So if you need this capability – Agilent has you covered.

milbus

Video Triggering and Analysis Application (DSOX3VID)

The DSOX3VIDEO option provides triggering on an array of HDTV standards, including:

  • 480p/60, 567p/50, 720p/50, 720p/60
  • 1080i/50, 1080i/60
  • 1080p/24, 1080p/25, 1080p/30, 1080p/50, 1080p/60
  • Generic (custom bi-level and tri-level sync video standards)

The 3000X Series oscilloscope already comes standard with NTSC, PAL, PAL-M, and SECAM support. Example of video analysis:

dsox3vid

Audio Serial Triggering and Analysis (DSOX3AUDIO)

And not surprisingly this is an option to allow decoding of and triggering from I2S digital audio data. For example:

i2s_decode

Mask Limit Testing (DSOX3MASK)

This is another interesting and useful option, idea for quality testing, benchmarking and so on. First you create a mask by measuring the ideal waveform, and then feed in the signal to be compared with the ideal mask. Mask limit testing can operate at up to 280000 comparisons per second. You can view pass/fail statistics, minimum sigma and so on, for example – a perfect test:

mask1

… then a change of frequency for a few cycles:

mask2

Furthermore you can specify the number of tests, change source channel, specify action upon errors, etc. Finally you can create and save to USB your own mask file for use later on – which can also be modified on a PC using any text editor software. Or for other monitoring options the external trigger socket on the read of the MSO can be configured to give a 5V pulse on a mask test failure.

If you have the LAN/VGA module you could place the MSO on in a lab or factory situation and monitor the testing over the network using a PC – very handy for QC managers or those who need to move about the workplace and still monitor testing in real time.

20MHz Function Generator/Arbitrary Waveform Generator (DSOX3WAVEGEN)

The “WaveGen” function is a versatile option that offers a highly controllable 20 MHz function generator and arbitrary waveform generator. It offers eleven different types of waveform: sine, square, ramp, pulse, DC, noise, sine cardinal, exponential rise and fall, cardiac and gaussian pulse.

The frequency can be adjusted between 100mHz to 20 MHz in 100 mHz steps; period from 50ns to 10s; full offset, amplitude and symmetry control; as well as logic level preset outputs (such as TTL, CMOS 5V, 3.3V etc.) Finally the WaveGen can be operated independently to normal measurement tasks, which is useful for ideal vs. actual comparisons and so on. Output is from the BNC socket at the bottom-left of the front pane and sync is also availble from the rear BNC socket. The arbitrary waveform generator is very simple to use  – and copied waveforms can be edited or have noise added to them to replicate real-world waveforms.

Power Measurement (DSOX3PWR)

This is a power measurement and analysis option that is integrated into the unit and provides a quick and easy way of analysing the reliability and efficiency of switching power supplies. It also includes a user license for U1881A-003 PC-based power measurement and analysis software that provides even more powerful insight into power supply measurement. With this option you can:

  • Measure switching loss and conduction loss at the switching device (to help improve efficiency)
  • Analyse dI/dt and dV/dt slew rate (for reliable operation)
  • Automate oscilloscope set-up for ripple measurements (to eliminate tedious manual oscilloscope set up)
  • Perform pre- compliance testing to IEC 61000- 3- 2 standards (to reduce compliance testing time)
  • Analyse line power with total harmonic distortion, true power, apparent power, power factor, and crest factor tests (to quickly provide power quality information)
  • Measure output noise (ripple)
  • Analyse modulation using the on- time and off- time information of a Pulse Width Modulation (PWM) signal (to help characterize the active power factor)
  • Measure how well a circuit rejects ripple coming from the input power supply at various frequencies with the Power Supply Rejection Ratio (PSRR) measurement.
For more indepth explanation of this option download and read the well written manual.

Etch-a-sketch

Well not a feature as such, but it exists if you know where to find it:

msoxes

Initial Conclusions

There is no doubt that the Infiniivision 3000-series are a great line of instruments. The waveform sample rate, memory size and bandwidth options are very competitive, and the ability to add various options is convenient and also helps lower the final cost for purchasing departments. (Start with the base model then hit them up for the options over time)

However there are a few things that could use improvement. Although the display is excellent – the right-hand column with “Agilent” at the top is always displayed. This is a waste of LCD space and there should be an option to turn it off, allowing waveforms to be displayed across the entire screen. If a $400 Rigol can do this, so should a $5000+ Agilent. The build unit of the unit is good, no problems are evident however it could be a little more “solid”; and the option of a clear shield for the LCD would be a great idea to protect against forceful and dirty fingers.

Furthermore the ground demonstration terminal suffers from metal fatigue very quickly, it already is somewhat chipped and may need replacing if you used it quite often. Finally, it would have been nice to see Agilent include the a carry bag – already people have asked to borrow the unit and to wander around with it in the box is somewhat awkward.

For those who rely on their test equipment will have the peace of mind that Chinese discount suppliers cannot give you – Agilent support exists and will not ignore you once a sale has been made. It doesn’t take long to find a tale of woe on an Internet forum from someone who imported their own “high-spec” DSO via eBay or direct east-Asian sellers only to find there are no firmware updates, competent English-speaking support or warranty of any kind. Furthermore, the ability to combine many functions in the one piece of equipment saves space, time and reduces your support channel back to one supplier. There is also an iPhone “app” that may be of interest – however as an Android user I haven’t tried it.

The saying “Quality is remembered long after price is forgotten” certainly holds true – and at the end of the day combined with the mix of standard and optional features at various price points – the Agilent Infiniivision MSO-X 3024A rises to the top echelon of test equipment.

 The Agilent Technologies Infiniivision MSO-X 3024A Mixed Signal Oscilloscope used in this review is a promotional consideration received from Agilent and element-14 via their Road Test program.

Agilent Test and Measurement equipment is available from your local element-14Farnell or Newark distributor.

Australian readers please note:  Trio Smartcal are the exclusive Australian Agilent distributors for all states except WA and NT – telephone 1300 853 407.

Measurement Innovation for WA and NT – telephone 08 9437 2550

High-resolution images are available on flickr.

Once again thanks for reading, have fun and keep checking into tronixstuff.com. Why not follow things on twitterGoogle+, subscribe  for email updates or RSS using the links on the right-hand column, or join our Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

Posted in agilent, DSO, MSOX3024A, oscilloscope, review, test equipment, tutorial

Kit review – Sparkfun Frequency Counter kit

Hello everyone

Today we examine a kit that is simple to construct and an interesting educational tool – the Sparkfun Frequency Counter kit. This is a revised design from a kit originally released by nuxie1 (the same people who brought us the original function generator kit). As a frequency counter, it can effectively measure within the range of 1 to a claimed 6.5 MHz. Unfortunately the update speed and perhaps accuracy is limited by the speed of the microcontroller the kit is based upon – the Atmel ATmega328. Arduino fans will recognise this as the heart of many of their projects.

Interestingly enough the kit itself is a cut-down version of an Arduino Duemilanove-standard board, without the USB and power regulation hardware. The ATmega328 has the Arduino bootloader and the software (“sketch”) is open source (as is the whole kit) and easily modifiable. This means you can tinker away with your frequency counter and also use your kit as a barebones Arduino board with LCD display. More about this later.

This becomes more obvious when looking at the PCB:

pcbss

It was a little disappointing to not find any power regulator or DC socket – you need to provide your own 5V supply. However Sparkfun have been “clever” enough to include a cable with JST plug and socket to allow you to feed the frequency counter from their function generator kit. In other words, buy both. Frankly they might as well just have produced a function generator with frequency counter kit all on one PCB. Anyhow, let’s get building.

The kit comes in a nice reusable stiff red cardboard box. One could probably mount the kit in this box if they felt like it. The components included are just enough to get by. The LCD is a standard 16 x 2 character HD44780-compatible display. (More on these here). It has a black on green colour scheme. You could always substitute your own if you wanted a different colour scheme:

partsss

An IC socket is not included. You will need to install one if you intend to reprogram the microcontroller with another Arduino board.

Assembly was quick and painless. I couldn’t find any actual step-by-step instructions on the internet (Sparkfun could learn a lot from adafruit in this regard) however the component values are printed on the PCB silk-screen; furthermore no mention of LCD connection, but the main PCB can serve as a ‘backpack’ and therefore the pins line up.

To make experimenting with this kit easier I soldered in some header pins to the LCD and matching socket to the main PCB; as well as adding pins for an FTDI cable (5V) to allow reprogramming direct from the Arduino IDE:

lcdsocketss

So there are in fact two ways to reprogram the microcontroller – either pull it out and insert into another Arduino board, or do it in-place with a 5V FTDI cable. Either way should be accessible for most enthusiasts. At this point one can put the screen and LCD together and have a test run. Find a nice smooth 5V DC power source (from an existing Arduino is fine), or perhaps plug it into USB via a 5V FTDI cable – and fire it up:

itworksss

Well, that’s a start. The backlight is on and someone is home. The next step is to get some sort of idea of the measurement range, and compare the accuracy of the completed kit against that of a more professional frequency counter. For this exercise you can observer the kit and my Tek CFC-250 frequency counter measuring the same function generator output:

As you can see the update speed isn’t that lively, and there are some discrepancies as the frequencies move upward into the kHz range. Perhaps this would be an example of the limitations caused by the CPU speed. Next on the to-do list was to make the suggested connection between the function generator kit and the frequency counter. This is quite simple, you can solder the included JST socket into the function generator board, and solder the wires of the lead included with the frequency counter as such:

boardsss

When doing so, be sure to take notice about which PCB hole is connected to which hole, the colours of the wire don’t match the assumed description on the function generator PCB. Furthermore, the voltage applied via the WAVE pin (the frequency source) should not fall outside of 0~+5V.

As mentioned earlier, this kit is basically a minimalist Arduino board, and this gives the user some scope with regards to modification of the software/sketch. Furthermore, the kit has been released under a Creative Commons by-sa  license. So you can download the schematic, Arduino sketch and EAGLE files and create your own versions or updates. If doing so, don’t forget to attribute when necessary.

Overall, this was anther interesting and easy kit to assemble. It is ideal for beginners as there isn’t that much soldering, they end up with something relatively useful, and if you have a standard Arduino Uno or similar board you can upgrade the firmware yourself.

However as a standalone frequency counter, perhaps not the best choice. Think of this kit as an educational tool – involving soldering, Arduino programming and learning how frequency counters work. In this regard, the kit is well suited.

As always, thank you for reading and I look forward to your comments and so on. Furthermore, don’t be shy in pointing out errors or places that could use improvement. Please subscribe using one of the methods at the top-right of this web page to receive updates on new posts. Or join our Google Group.

High resolution images are available on flickr.

[Note – The kit was purchased by myself personally and reviewed without notifying the manufacturer or retailer]

Posted in arduino, kit review, KIT-10140Comments (2)

Kit review – Sparkfun Function Generator

Hello readers

[10/09/2011 Update – It would seem that this kit has been discontinued – most likely due to the unavailability of the XR2206 function generator IC – which is a damn shame as it was a great kit. If you are ‘feeling lucky’ eBay seems to have a flood of them. Purchase at your own risk!]

Time for another kit review (anything to take the heat off from the kid-e-log!). Today we will examine the Sparkfun Function Generator kit. This is based from an original design by Nuxie and has now been given a nice thick red PCB and layout redesign. Although quite a bare-bones kit, it can provide us with the following functions:

  • sine waves
  • triangle waves
  • a 5V square wave with adjustable frequency

There are two frequency ranges to choose from, either 15~4544Hz or 4.1~659.87kHz. Your experience may vary, as these values will vary depending on the individual tolerance of your components.  The coarse and fine adjustment potentiometers do a reasonable job of adjustment, however if you were really specific perhaps a multi-turn pot could be used for the fine adjustment. With the use of a frequency counter one could calibrate this quite well.

The maximum amplitude of the sine and triangle waves is 12V peak to peak, and doing so requires a DC power supply of between 14~22 volts (it could be higher, up to 30 volts – however the included capacitors are only rated for 25V). However if you just need the 5V square-wave, or a lower amplitude, a lesser supply voltage such as 9 volts can be substituted. After running the generator from a 20V supply, the 7812 regulator started to become quite warm – a heatsink would be required for extended use. The main brains of the generator are held by the Exar XR2206 monolithic function generator IC – please see the detailed data sheet for more information.

Now what do you get? Not much, just the bare minimum once more. Everything you need and nothing you don’t …

bagpartsss

Upon turfing out the parts we are presented with:

thepartsss

Not a bad bill of materials – nice to see a DC socket for use with a plug-pack. Considering the XR2206 is somewhat expensive and rare here in the relative antipodes, an IC socket would be nice – however I have learned to just shut up and keep my own range in stock now instead of complaining. Having 5% tolerance resistors took me as a surprise at first, but considering that the kit is not really laboratory-precision equipment the tolerance should be fine. One could always measure the output and make a panel up later on.

Once again, I am impressed with the PCB from Sparkfun. Thick, heavy, a good solder mask and descriptive silk-screen:

pcbss

Which is necessary as there aren’t any instructions with the kit nor much on the Sparkfun website. The original Nuxie site does have a bit of a walk through if you like to read about things before making them. Finally, some resistors and capacitors included are so small, a decent multimeter will be necessary to read them (or at least a good magnifying glass!).

Construction was very simple, starting with the low-profile components such as resistors and capacitors:

resiscapsss

followed by the switches, terminal blocks, IC sockets and the ICs:

icsss

and finally the potentiometers:

potsss

The easiest way to solder in the pots while keeping them in line was to turn the board upside down, resting on the pots. They balance nicely and allow a quick and easy soldering job. At this point the function generator is now ready to go – after the addition of some spacers to elevate it from the bench when in use:

finishedss

Now for the obligatory demonstration video. Once again, the CRO is not in the best condition, but I hope you get the idea…


Although a very simple, barebones-style of kit (in a similar method to the JYETech Capacitance meter) this function generator will quickly knock out some functions in a hurry and at a decent price. A good kit for those who are learning to solder, perhaps a great next step from a TV-B-Gone or Simon kit. And for the more advanced among us, this kit is licensed under Creative Commons attribution+share-alike, and the full Eagle design files are available for download – so perhaps make your own? High resolution images are available on flickr.

[Note – The kit was purchased by myself personally and reviewed without notifying the manufacturer or retailer]

 In the meanwhile have fun and keep checking into tronixstuff.com. Why not follow things on twitterGoogle+, subscribe  for email updates or RSS using the links on the right-hand column? And join our friendly Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

Posted in education, kit review, KIT-10015, learning electronics, oscilloscope, test equipment, XR2206Comments (0)

Add a real-time clock to the Freetronics Eleven

Let’s add a DS1307 real-time clock to our Freetronics Arduino-compatible board.

Updated 18/03/2013 – this is also perfect for the Freetronics Eleven board.

Now and again I find myself making another kind of clock or timing device using the Arduino system, and each one has been making use of the Maxim DS1307 real-time clock IC. However every time another clock is being worked on, my DS1307 real-time clock shield needs to come out to play. Although in itself it is a nice shield, at the end of the day – the less you have the better. Originally I used a Freetronics TwentyTen board – which has now been superseded by their Eleven board, however they’re both identical for the purposes of this tutorial.

So what to do? As regular readers will know, my preferred board is the Freetronics Eleven, and within this we have a solution to the following problem:

problemss

The Freetronics team have thoughtfully provided a prototyping area in their board – and that will be a perfect home for the real time clock system. Being a cheapskate and a masochist – instead of  following others by using a smaller RTC module I will instead use parts already in stock (except for the battery) and install my own circuit. So, as always – we need a plan. The circuit itself is quite simple, the DS1307 data sheet has a fine example on page thirteen, and here is my interpretation:

schematicss

So the parts required for our clock circuit will be:

  • IC1 – Maxim DS1307 I2C real-time clock IC
  • 8-pin IC socket
  • R1~R3 – 10k ohm 1% metal film resistors
  • X1 – 32.768 kHz crystal
  • B1 – Panasonic CR1220 3v battery with solder pins (Farnell part number 1298944) [data sheet one and two]
  • One header pin (from those 40-way strips)
  • some thin black single-core wire

The CR1220 battery was chosen over the usual CR2032 due to the smaller diameter. According to the DS1307 data sheet, the battery should last around ten years if it has a capacity of 48 mAh. Our CR1220 is 35 mAh – which will do nicely, perhaps seven years or so. That will have to do. Don’t forget to check the voltage of the battery before installation – it should be just over three volts.

Now to get everything arranged in the prototyping area. When doing this it pays to always have the schematic in front of you as well so you can refer to it when necessary. Planning to use protoboard of any size requires a good plan as well. After spending some time considering component placement, the final layout was as follows:

layoutsss

Each square on the grid represents one hole on the board. After you see the images below, everything will make sense. Before soldering away, it will pay to give the prototyping area a quick clean with some PCB cleaner.

Now it is finally time to get soldering. The first items were the battery, crystal and the resistors. Although the battery was designed to be soldered, I am always a little wary when applying heat to them. Two seconds with the hot iron was enough.

When soldering in the crystal (or anything else), try to keep in mind what the leads will be connecting to. For example, the crystal legs will need to connect to pins 1 and 2 of the IC socket. So bend the crystal leads in the direction of the respective IC socket pins. Doing so will make creating solder joins between them much easier:

The resistors were simple enough. Keep the excess clippings to make jumpers with later. Also notice how the right hand leg of R3 was bent around and brought back up to the top row – this is to help make connections with the 5V rail link:

resisleadsss

The next item was the IC socket. Nothing to worry about there, just drop it in and solder away. Don’t forget to bridge the crystal pins to socket pins one and two, and the battery positive pin to IC socket pin three.

Next for the SQW pin. The DS1307 can also output a nice square wave at either 1Hz, 4.096 kHz, 8.192 kHz or 32.768 kHz, with the resulting signal being found on pin 7. It isn’t something really used that often, but you never know. So I soldered in one of these pins, which should make it easy enough to use later on:

Note that if you are using the SQW function, the DS1307 will merrily pulse away once it is set, until the power is cut – the square-wave generator is autonomous to the I2C bus once it has been set. And it remembers (as long as the backup battery is fine). For example, you can upload a sketch to set the SQW to 4.096 kHz, remove power, yank out the ATmega328, power up – and the SQW is still active.

Next we turn the board over, and solder in our jumper wires:

backlinkss

The lead on the top runs from the right-hand side of the pull-up resistors R1~R3 (when facing the top of the board) to the 5V pad. The bottom lead runs from pin four of the IC socket to the GND pad. The negative pin of the battery is also bent over and soldered to the GND pad. Also, connect all the resistors together as shown in the above image (below the TX pin). The next step is turn the board back over and make some more wired connections, the first being pin eight of the IC socket to the resistors and then to the 5V link on the rear:

toplinksss

The next are somewhat longer, they are the leads for the I2C bus. Run a wire from next to IC socket pin six all the way to (and through) the bottom-right hole of the TwentyTen (when facing the top); this will be the SCL line and soldered to analogue 5. Repeat again from IC socket pin five, this is the SDA line (as above) for analogue 4. The joints you have to solder them onto are not that large, however it can be done. Before soldering the wires in, heat up the existing joint to melting point then let it cool again – this makes actually soldering the wire in a lot easier:

i2css

And there we have it. At this stage, don’t plug the board in. Do some quality control: check that the soldered joints are complete; check that solder has bridged where you need it, and not where you don’t; use the continuity function (‘beeper’) of a multimeter to spot-check for shorts, and also follow the new 5V and GND lines to ensure they are connected correctly. And finally, insert the DS1307 IC into the socket.

finishedss

OK – now for some test timing. If you have not worked with the DS1307 IC before, there is a full explanation of how it works within our Arduino tutorials. Here’s a sketch you can use to test the real-time clock. Once you have uploaded that sketch, open the serial monitor box at 9600 bps, and you should have something like this:


Now let’s check the 1 Hz output from the SQW pin:

Recall that you can generate four frequencies with your DS1307, here is an example sketch that does just that:

and here is the result – measured on a freqency counter:

My frequency counter is around twenty-two years old, please be patient with it as the sampling rate is not the best.

In the meanwhile have fun and keep checking into tronixstuff.com. Why not follow things on twitterGoogle+, subscribe  for email updates or RSS using the links on the right-hand column? And join our friendly Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

Posted in arduino, clocks, ds1307, freetronics, hardware hacking, learning electronics, microcontrollers, tutorialComments (4)

Review – Ikalogic SCANALOGIC2 Logic Analyser/Signal Generator

Hello Readers

Today we will take a first look at the Ikalogic “Scanalogic2” PC-based logic analyser and signal generator. This is a tiny and useful piece of test equipment that should be useful for beginners and experienced engineers alike. It has been developed by two guys in Europe that are dedicated to the craft, and I wish them well. First of all, let’s pull it out of the box and see what we have:

contentssss

Upon opening the box, one finds a USB cable, the connector leads and the unit itself. It really is small, around 60 x 35 x 20mm. The USB cable is just under 900mm long. Finally a small instruction and welcome postcard which details a quick overview of the software and the unit’s specifications. Ikalogic are to be congratulated for the minimal level of packaging – finally a company that realises one can download the required items instead of printing books, burning DVDs and causing an increase in shipping weight.

The first thing you will need to do is download the latest software. It needs a Windows-based PC with .net framework. Installing took about two minutes, then the ubiquitous system restart. Finally the last preparation is to check for the latest firmware and update it. This is a simple procedure – download a .zip file, extract the .hexe file, then just file>update device firmware in the software. The desktop software checks for new versions before every startup, so you can be sure of having the latest version.

Here are the specifications of the unit from their web page:

specs

Certainly there is a lot there to take advantage of. Personally I consider the logic analyser functions to be of great interest, and will now demonstrate those to see how they can be useful in debugging and generally figuring out what my designs are up to.

One can capture data in two ways, either by using a live sampling mode, or capture mode where you set the device to sample data into its memory, and then reviewing the data using the software. If you are using the live mode, the quality of the sampling will be affected by your PC resources. For example, consider this first demonstration. A very simple Arduino is setting a pin high and low:

demo1ss

In live mode you can still use the horizontal scroll feature to move backwards and forwards through the captured data. One can also expand the data display to the full width of the window. When using the live mode, I found that there was still some variation in the logic levels that was not programmed for. My PC is fairly up to date, consisting of an AMD PhenonII dual-core 3.1 GHz CPU, 2GB RAM at 1066 MHz, running Windows 7 x64. Perhaps I could use some more RAM? A better video chipset? Who knows… Unfortunately I don’t have a more powerful PC to test. Therefore I will stick to the normal capture mode. Doing so is also quite easy – here is the basic setup tab:

It is pretty self-explanatory. If you have a fair idea of your sampling rate, you can drop it down to increase the available sampling time. Here I have selected the lowest sampling rate, as I will just capture the pulses as shown in the earlier demonstration. Once your sample has been collected, you can scroll through it at your leisure, and also save the sample to disk.

In being able to save the data for later retrieval, there are three things that can be done with the data:

  1. As anyone can download the software, you can share your samples by emailing or sharing the files with colleagues – they can playback the sample without owning a Scanalogic themselves, by just using the software;
  2. You can keep the sample for later analysis
  3. You can blast out the captured data using the function generator feature. Neat! Let’s do that now…

Earlier on I captured the following from an Arduino board:

demo3ss

And now I can just right-click on the data (channel one) and select run data generator for this channel then click start on the left. Which results in the following output:

Very good (except for my old CRO). Also notice the log area at the bottom of the application screen – it relays unit status, error messages and so on. Now let’s capture and look at some more interesting sample data. The following example is an example of captured data from an Arduino serial-out pin, which was programmed to send the letter “A” out at 2400 bps using serial.write();

uartdemoss

Once you have captured the sample, you can select the parameters of the data stream and decode the sample. As you can see in the image above, the decoder shows the data stream in hexadecimal and the ASCII equivalent.

Next on the test is I2C. This is a common two wire data bus from Philips/NXP, used in many systems. More about I2C with Arduino is here. A very popular example of an I2C IC is the Maxim DS1307 real-time clock. We can use our Scanalogic to eavesdrop on the SCA and SCL data lines to see what is being said between the microcontroller and the DS1307:

i2cone

So in the example above, the value 0x68 (binary 1101000) is sent down the bus. This is the unique identifier (slave address) for a DS1307 IC. So the Arduino is saying “Hey – DS1307 – wake up”. This is then followed by a 0x00 or directional bit. The DS1307 then replies by sending the time data back to the bus. The first piece of data in the reply is 0x68, which identifies to the I2C bus (recall that 0x68 is the DS1307 identifier) that the data is from the DS1307. Following this is the time and data data in hexadecimal, which is converted to binary-coded decimal in the microcontroller software.

When working with I2C, it really pays to have the data sheet for your IC with you. Then you can decipher the data, direction and timing with the sample data on one side and the timing diagrams on the other. For example, page twelve of the DS1307 data sheet. In doing so, it reminds me how much I dislike I2C 🙂

Moving along. Next we will have a look at some data from the SPI (serial peripheral interface) lines. Again, this is quite simple, you just connect the four hooks into the clock, MOSI, MISO and CS lines, and capture away. The software allows you to select which hook is connected to which line, so you can connect up quickly. At this point I will note that the IC hooks are somewhat inexpensive, and the designers could have spent a few more Euro on including some decent ones. Anyhow, here is the screen dump:

spidemo

At this point one can realise all sorts of monitoring possibilities. I wish I had one of these years ago when learning digital electronics – you could just monitor the highs and lows over four channels and debug things very quickly. Will keep this in mind when I get around to making a TTL clock.

Anyhow – the Scanalogic2 has a lot going for it in terms of data capturing ability, the price is right, you can update the software and firmware very easily, and the desktop software is freely available in order to share samples with others. There are a few cons though – the IC hooks could be better (I couldn’t connect four in a row onto an IC for the life of me); the unit could use some documentation in terms of a “Getting Started” guide or webpage – so due to this the learning curve is quite high. There is their version here, but I feel it could be expanded upon. Many beginners and amateurs will be attracted to this unit due to the price. However there is a support forum and so on, but answers can vary in quality and time. However, don’t let the cons put you off – this thing is cheap, the software is very good – and it works. Two thumbs up!

To purchase a Scanalogic2, visit the Ikalogic home page. If you need to analyse some data, and don’t want to spend a bucket of money – this is for you.

Posted in ikalogic, product review, review, Scanalogic, test equipmentComments (4)


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