Tag Archive | "display"

Kit review – ogi lumen Nixie Tube system

Hello readers

Time to finish off the month with a fascinating kit review  – the ogi lumen nixie tube system. The younger readers amongst us may be thinking “what is a nixie tube?” Here is an example of four in a row:

p1080918

If you cast your mind back to before the time of LCDs, and before LEDs… to the mid-1950s. Nixie tubes were used to display data in various forms on electrical devices, from test equipment, scales, elevator indicators, possible doomsday machines, clocks – anything that required visual output would be a candidate. Although nixie tubes are now totally out of date, as with many things there is a growing trend to use them again, for cool retro-style, nostalgia and those people who enjoy living in the past.

How nixie tubes work is quite simple, an element is within a vacuum tube full of gas, such as neon. When a high-voltage (~190 volts DC) current flows through the element, it glows. For more information, here is a great explanation. You will note that they are similar to in look but different in design to the vacuum-fluorescent displays, as used in the ice tube clock reviewed a few months previously. The tubes used in this kit are the Soviet model IN-12A:

p1080865

The IN-12A tube can display the digits zero to nine, with a nice orange glow.  For the uninitiated, sourcing and making nixie tubes can be quite difficult. Apart from procuring the tubes themselves, you need a suitable power supply and logic ICs that can handle the higher voltage to control the tubes. Thankfully Ogi Lumen have put together a system of kits to make using these nixie tubes simple and interesting. There are three components to the system, the first being the power supply:

p1080879

Note that the power supply is preassembled. This supply can generate the necessary 150 to 220 volts DC to energise our nixie tubes. Yes – up to 220 volts! For example:

p1080922

However the current required is quite small – one power supply can handle up to twenty-four IN12A nixie tubes. My example in the photograph above is drawing 110~120 milliamps from a 12V DC supply. For those of you assembling these kits, please be careful. It can be easy to physically move the kit about whilst in operation, and touching the live HV pads will hurt a lot. After bumping the HV line on the PCB, my whole left arm went into a spasm and hurt for the time it took to see my doctor. So be careful.

The second item required is the driver kit. This is a board that takes care of the shift-registers and power for two of the nixie tubes. Driver kits can be slotted together to form a row of nixie tubes. The third and final item is the nixie duo kit. This contains two IN-12A tubes, matching sockets and a PCB to muont them. This PCB then slots into the driver kit PCB. You can buy the driver and duo kit as a set for a discount.

From a hardware perspective, assembling the kits is relatively simple. There isn’t any tricky soldering or SMD to worry about, however you will need a lot of solder. The contents of the duo and driver kits are as follows:

p1080869

Before you start soldering, please download and take note of the instructional .pdf files available for the duo and driver board kits. Assembling the driver kit (on the right) is very straight forward. However – please read the instructions! An interesting part of note is the K155ИД1IC:

p1080872

This is the Russian equivalent of the 74141. This is a BCD-decimal decoder IC that can handle the high voltages required for nixie tubes. When soldering the resistors, take care with R2 – it will need to be positioned horizontally so as to not rub against the duo board:

p1080934

When it is time to assemble the duo board, you will need time and patience. At a first glance, one would imagine that the sockets drop into the PCB, and the nixie tubes will happily be seated into the sockets. This is not so, don’t solder in the sockets first! The pins on the bottom of the socket also form part of the socket for the tube legs – which can alter the positioning of the socket legs. Make sure you have the socket with pin 1 at the top of the PCB. After some trial and error, the best way to insert the tubes is to first partially place the sockets into the PCB:

p1080880

… then fully insert the tubes into their sockets. Make sure the tube is the right way up – check that the digit 3 in the tube is the right way up. Then push the whole lot into the PCB. At this point you should check to make sure the sockets are in line with each other:

p1080892

(Notice how thick the PCB is…) At which point you can solder them in, followed by the row of connector pins:

p1080896

By this stage you will need some fresh air from all that soldering. The PCB holes for the socket pins really take a lot. Now you can connect the power supply to the driver board and give the tubes a test-toast:

p1080941

All the tubes should have their elements glowing. This is a good start. The next step is to connect the appropriate microcontroller and start displaying. As noted in the instructions, the 74141 BCD-decimal ICs are controlled by standard 74HC595 shift-register ICs, so your microcontroller needs to send out a data, clock and latch line. My following examples have been created using the Ardiuno system and a compatible board.

The first example is a method of displaying integers. It uses the Nixie library which you can download here.

That was just an arbitrary demonstration to get some numbers displayed. Here is a short video clip of it in action:

Now for another, more useful example. By using a DS1307 real-time clock IC with the Arduino, we can make a nice clock that displays the time and date. For more information on using the DS1307 with Arduino, please visit this tutorial. You can download the example nixie clock .pde file from here. And finally, here is the clock in action:

The problem with these tubes is that you will never have enough. Already I have thought of a few things to make that require a lot more tubes, so in the next month or so stay tuned to tronixstuff.com as there will be more projects with these kits.

In conclusion, this was a great kit and anyone looking to use some numerical nixie tubes will do very well with the Ogi Lumen products. Furthermore the designs are released under Creative Commons by-sa-nc, and the files are available to download from the product pages. And finally, it is a lot of fun – people will generally ask you about the tubes as they may have never seen them before.

Remember, if you have any questions about these modules please contact Ogi Lumen via their website. Higher resolution images available on flickr.

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.

[Note – the kit assembled in this article was received from Ogi Lumen for review purposes]

Posted in arduino, kit review, learning electronics, nixie, ogilumenComments (11)

Various 555 Timer circuits

Hello readers

The purpose of this article is to follow on from our explanation of the 555 timer IC by demonstrating some simple yet interesting, noisy and plain annoying uses of the 555. They are by no means that complex, and intended to help move theory into practice.

Button de-bouncer

De-bouncer? How does one bounce a button in the first place? Many years ago I bounced a button on the arcade Sonic the Hedgehog – hit it so hard it popped out and bounced over the table… But seriously, when working with digital logic circuits, you may need to use  a momentary button to accept user input. For example, to pulse a trigger or so on. However with some buttons, they are not all that they seem to be. You press them once, but they can register multiple contacts – i.e. register two or more ‘presses’ for what seems like only one press. This could possibly cause trouble, so we can use a 555 timer monostable circuit to solver the problem. In our de-bounce example, when the button is pressed, the output is kept at high for around half a second. Here is the schematic:

555debouncesch

What we have is a basic monostable timer circuit. For my example the output delay (t) is to be half a second. The formula for t is: t=1.1xR1xC1. The closest resistor I had at hand was 2k ohms, so to find the required value for C1, the formula is rearranged into: C1=t/(1.1xR1). Substituting the values for t and R1 gives a value of C1 as 227.274 uF. So for C1 we have used a 220 uF capacitor.

Now for a visual demonstration of the de-bouncer at work. In the following video clip, the oscilloscope is displaying the button level on the lower channel, and the output level on the upper channel. The button level when open is high, as the 555 requires a low pulse to activate. The output level is normally low. You can see when the button is pressed that the button level momentarily drops to low, and then the output level goes high for around half a second:

Make some noise

As we know the 555 can oscillate at frequencies from less than 1Hz to around 500 kHz. The human ear can theoretically hear sounds between (approximately) 20 and 20 kHz. So if we create an astable timing circuit with an output frequency that falls within the range of the human ear, and connect that output to a small speaker – a range of tones can be emitted.

The circuit required is a standard 555 astable, with the output signal heading through a small 8 ohm 0.25 watt speaker and a 4.7 uF electrolytic capacitor to ground. The capacitor stops any DC current flowing to ground, without this we will overload the current-handling ability of the 555. (I couldn’t help myself by trying it without the capacitor – pulled 550 mA from the 555 before it stopped working…). To choose the values of R1 and C1 to emit out required frequency, the following formula is used: f (frequency) = 1.4 / {(R1 + [2 x R2]) x C1}. To cover the range required, a 100k ohm trimpot was used for R1. Here is the resulting schematic:

noisemakersch

The input voltage can fall within the specification of the 555, however for optimum results a supply of between 5 and 9 volts DC should be used. In the following demonstration, we used a 9V supply. The purpose of the video is to learn the relationship between the tones and their frequencies. You can see the frequency on my old counter and hopefully hear the result:

Our next example is to create a  siren effect, using two 555 circuits – one for a low frequency and one for a high frequency. To determine the value for R1 for the low and high frequency, I used the previous circuit and chose two tones that were quite different, and measured the resistance of the trimpot (R1) at those frequencies. My R1 value for the ‘low’ tone is 82k ohm and 36k ohm for the ‘high’ frequency.

The switching between low and high frequency will be handled by a 4047 multivibrator – the Q and Q outputs will control NPN transistors. The transistors are used as switches to allow current to flow from the supply to the 555 high or low tone circuit. We use this method as the 4047 is not able to source enough current to drive the 555 circuits. Here is the schematic:

555siren

Don’t forget to connect pin 14 of the 4047 to supply voltage. This circuit has been tested with a supply voltage between 5 and 12 volts. As the supply voltage increases, so does the amplitude of the square wave emanating from the 555 output pins, which in turn in creases the volume of the siren. At 5 volts, the entire circuit drew only 20 milliamps. Speaking of which, you can listen to a recording of the output here. If you wish to alter the time for each tone, adjust the value of what is the 47k ohm resistor on pins 2 and 3 of the 4047.

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 4047, 555, arduino, COM-09273, education, learning electronics, lesson, tutorialComments (0)

Tutorial: Arduino and TFT LCD

Old and now unsupported tutorial for 4D Systems 1.44″ TFT serial interface LCD.

Update 20/04/2013 

The Arduino library for this module hasn’t been updated to work with Arduino v1.0.1+ – so you need to use Arduino IDE v22 or v23. And the module itself has been discontinued. For the time being I’m leaving the tutorial here until a more suitable item can be used. We can’t help you with the 4D module

Nevertheless – if you have one – here’s the subject of the tutorial- the 4D Systems 1.44″ TFT serial interface LCD:

The LCD is an LED-backlit thin-film transistor type, resolution is 128 x 128 pixels, with an RGB colour range of 65536.

As an aside, this is a very powerful piece of hardware. The module not only contains a 1.44″ square TFT LCD, there is also a dedicated graphics processor and a microSD card interface. One can program the display processor in the same manner as another microcontroller platform for incredibly interesting results. For more information, please visit:

http://www.4dsystems.com.au/prod.php?id=120

However in the spirit of keeping things simple, this article will focus on driving the LCD directly using our Arduino or compatible boards. There are two firmware versions of this module – the GFX and the SGC. We need to have the SGC firmware, as this allows control via the serial TX/RX pins from our Arduno board. If you have purchased the SGC module, you’re ready to go. Scroll down until you see “And we’re back…”. However if you have the GFX version, please read the following instructions on how to change your LCD’s firmware from GFX to SGC…

Changing the firmware from GFX to SGC

  • At the moment this process only seems available to users of Microsoft Windows. All complaints to 4D Systems.
  • Unfortunately this process may not work with an Arduino Mega board.
  • First of all, remove the ATmega328 from your Arduino board. Please be careful, use a chip puller if possible. We are going to use the board as a simple serial-USB converter;
  • Insert your LCD module into a solderless breadboard;
  • Connect Arduino pin 0 (RX) to display pin 7 (RX); connect Arduino pin 1 (TX) to display pin 8 (TX). [Yes – TX>TX, RX>RX];
  • Connect Arduino 5V to display pin 9; connect Arduino GND to display pin 6; your LCD should display the following:

beforesgc

  • Visit http://www.4dsystems.com.au/prod.php?id=46, download and open the PmmC Loader application; visit http://www.4dsystems.com.au/prod.php?id=120 and download the .pmmc file to your local drive;
  • Connect your Arduino board via USB to the computer; then run the PmmC loader application;
  • Select the appropriate COM: port, load in the .pmmc file, then click Load. The firmware update should take less than sixty seconds;
  • When finished, you will be presented with the following on the computer:

progfinish

… and the following on your LCD:

aftersgcss

  • At this point unplug the USB lead from your Arduino board and all leads into the Arduino board;
  • Re-insert the ATmega328 back into your Arduino board;
  • Reconnect the wires from the LCD module to the Arduino, but this time connect Arduino TX to LCD RX; and LCD TX to Arduino RX.
  • Now you have  the serial-interface SGC firmware model LCD.

And we’re back…

To control this LCD, it requires commands to be sent via Serial.write(), and such commands are in the form of hexadecimal numbers. (You see something new every day). You can download the reference book with all the commands:

http://tronixstuff.com/wp-content/uploads/2011/02/goldelox-sgc-commands-sis-rev3.pdf

and bypass the library by directly writing the hexadecimal numbers directly to the module.

However, to get up to speed as fast as possible we can use a library with more of the popular functions included. Kudos and thanks to Oscar Gonzalez for writing a very useful library. Download the library from:

http://code.google.com/p/displayshield4d/downloads/list

and install into your ../Arduino-002x/libraries folder, then re-start the Arduino IDE if you had it running. You may be wondering why the library is named displayshield4d – the LCD manufacturer sells this LCD on an Arduino shield. Although that would be great for experimenting, one would need to purchase another standalone LCD if their project moved forward – myself included. So that’s why we’re using the bare LCD board.

To connect the LCD to our Arduino is very simple:

  • LCD pin 5 to Arduino RST;
  • LCD pin 6 to Arduino GND;
  • LCD pin 7 to Arduino D1;
  • LCD pin 8 to Arduino D0;
  • LCD pin 9 to Arduino 5V.

In the following examples we will demonstrate the various functions available in the library. As this is chapter 29, I will no longer explain the more basic functions or ideas that you should know by now, instead relying on comments within the sketch if it feels necessary. It can take a short moment for the LCD controller to process, so always put a short delay between functions.

When uploading a sketch to your Arduino you may need to disconnect the LCD from Arduino D0/D1 as it can interfere with the serial process.

Firstly we will demonstrate text display. Initialising the display requires a few functions:

The second line creates an instance of lcd to be used with the relevant functions. Next, within void setup():

To write text to the LCD, the following function is required:

This line sets the font transparency. If we use the parameter OLED_FONT_TRANSPARENT the unused pixels in the character area will be transparent and continue to show what they were set to before the text was over-written with. You can also use OLED_FONT_OPAQUE, which blocks the item displayed “behind” the text.

Whenever a function requires a colour parameter, we use:

where x, y and z are numerical values (between 0 and 255) for the red, green and blue components of the required colour. If you need an RGB numerical reference, download this handy chart. Finally, to display some text we use the following:

The parameters required are:

  • a – the x-position of the first character. E.g. if this was a zero, the top-left pixel of the first character would be on the left-most pixel column of the LCD;
  • b – the y-position of the first character. e.g. if both a and b were zero, the text would start from the top-left of the LCD;
  • c – numerical code for the font to use: 1 is for 5×7 pixel characters, 2 for 8×8 and 3 for 8×12;
  • the three values within the lcd.RGB() function determine the colour of the text;
  • d – x-axis resolution multiplier. E.g. if you double this and use the 5×7 font, the characters will be double-width;
  • e – y-axis resolution multiplier.

Now let’s see this in action with the following sketch:

And a short video clip of the example in action: – http://www.youtube.com/watch?v=t3yypXL022w

As you can see the display update speed is much better than the LCD from the previous chapter. Although this example was short, don’t be afraid to try out your own parameters in the example sketch.

Next we will demonstrate the various graphics functions in the library. Creating graphics isn’t rocket science, it just takes some imagination (something I admit to lacking) and following the parameters for each function. Our first is

which places a pixel on the screen at location x,y of colour described using lcd.RGB(). Next we have

which draws a line from x1, y1 to x2, y2 of colour rgb. One can also create rectangles and so on using

This will create a rectangle with the top-left point at x,y; width is l pixels, height is h pixels, and a new parameter z. If z is 0, the function will draw a solid shape, if z is 1, it will display only a wire-frame rectangle with a pixel width of one. Circles are created using

where x and y are the coordinates for the centre of the circle, r is the radius, and z is the solid/wireframe parameter. And finally – triangles:

This will draw a triangle with the corners at the coordinate parameters; z again is the solid/wireframe parameter. However you need to order the corners in an anti-clockwise order. This will become evident in the example sketch below. In this example we run through the graphical functions described above. By following through the sketch you should gain an idea of how the graphical functions are used, in order to create your own displays.

And here is the video of example 29.2 in action … brought to you by Mr Blurrycam: – http://www.youtube.com/watch?v=BKy-GuKWGZ8

 

Posted in 4d systems, arduino, education, LCD, learning electronics, lesson, microcontrollers, TFT, tutorial

Tutorial: Arduino and Colour LCD

Learn how to use the colour LCD shield from Sparkfun in chapter twenty-eight of a series originally titled “Getting Started/Moving Forward with Arduino!” by John Boxall – A tutorial on the Arduino universe. The first chapter is here, the complete series is detailed here.

Updated 19/02/2013

Although there are many colour LCDs on the market, I’ve chosen a relatively simple and popular model to examine in this tutorial – the Sparkfun Color LCD shield:

If you buy one note (shown above) that stacking headers aren’t supplied or fitted to the shield. If you get a header pack from Sparkfun or elsewhere – order PRT-10007 not PRT-11417 as the LCD shield doesn’t have the extra holes for R3 Arduino boards. However if you do have an Arduino R3 – relax … the shield works. While we’re on the subject of pins – this shield uses D3~D5 for the three buttons, and D8, 9, 11 and 13 for the LCD interface. The shield takes 5V and doesn’t require any external power for the backlight. The LCD unit is 128 x 128 pixels, with nine defined colours (red, green, blue, cyan, magenta, yellow, brown, orange, pink) as well as black and white.

So let’s get started. From a software perspective, the first thing to do is download and install the library for the LCD shield. Visit the library page here. Then download the .zip file, extract and copy the resulting folder into your ..\arduino-1.0.x\libraries folder. Then restart the Arduino IDE if it was already open.

At this point let’s check the shield is working before moving forward. Fit it to your Arduino – making sure the shield doesn’t make contact with the USB socket**. Then open the Arduino IDE and upload the TestPattern sketch found in the Examples folder. You should be presented with a nice test pattern as such:

It’s difficult to photograph the LCD – (some of them have very bright backlights), so the image may not be a true reflection of reality. Nevertheless this shield is easy to use and we will prove this in the following examples.

At the start of every sketch, you will need the following lines:

as well as the following in void setup():

With regards to lcd.init(), try it first without a parameter. If the screen doesn’t work, try PHILIPS or EPSON instead. There are two versions of the LCD shield floating about each with a different controller chip. The contrast parameter is subjective, however 63 looks good – but test for yourself. Now let’s move on to examine each function with a small example, then use the LCD shield in more complex applications.

The LCD can display 8 rows of 16 characters of text. The function to display text is:

where x and y are the coordinates of the top left pixel of the first character in the string. Another necessary function is:

Which clears the screen and sets the background colour to the parameter colour.  Please note – when referring to the X- and Y-axis in this article, they are relative to the LCD in the position shown below. Now for an example – to recreate the following display:

… use the following sketch:

In example 28.1 we used the function lcd.clear(), which unsurprisingly cleared the screen and set the background a certain colour. Let’s have a look at the various background colours in the following example. The lcd.clear()  function is helpful as it can set the entire screen area to a particular colour. As mentioned earlier, there are the predefined colours red, green, blue, cyan, magenta, yellow, brown, orange, pink, as well as black and white. Here they are in the following example:

And now to see it in action. The colours are more livid in real life, unfortunately the camera does not capture them so well.

Now that we have had some experience with the LCD library’s functions, we can move on to drawing some graphical objects. Recall that the screen has a resolution of 128 by 128 pixels. We have four functions to make use of this LCD real estate, so let’s see how they work. The first is:

This functions places a pixel (one LCD dot) at location x, y with the colour of colour.

Note – in this (and all the functions that have a colour parameter) you can substitute the colour (e.g. BLACK) for a 12-bit RGB value representing the colour required. 

Next is:

Which draws a line of colour COLOUR, from position x0, y0 to x1, y1. Our next function is:

This function draws an oblong or square of colour COLOUR with the top-left point at x0, y0 and the bottom right at x1, y1. Fill is set to 0 for an outline, and 1 for a filled oblong. It would be convenient for drawing bar graphs for data representation. And finally, we can also create circles, using:

X and Y is the location for the centre of the circle, radius and COLOUR are self-explanatory. We will now use these graphical functions in the following demonstration sketch:

You can see Example 28.3  in the following video. (There’s a section in  the video showing semi-circles – however this isn’t possible with the new Arduino v1+ library).  For photographic reasons, I will stick with white on black for the colours.

So now you have an explanation of the functions to drive the screen – and only your imagination is holding you back.  ** Get an Eleven board – it has a microUSB socket so you don’t run the risk of rubbing against shields. For another example of the colour LCD shield in use, check out my version of “Tic-tac-toe“.

LEDborder

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 arduino, education, LCD, LCD-09363, lesson, microcontrollers, tutorialComments (3)

Review – Fluke 233 Remote Display True RMS Multimeter

Hello readers

Several followers of my website have noticed the use of an interesting multimeter in a few of my articles, and were curious about it. So in this article we will discuss it in more detail. It is certainly novel in design, and has proven to be very convenient in use – the Fluke 233 remote-display true RMS multimeter. It arrives in a cardboard box that is easily recycled:

boxs

Upon tearing open the packaging we are presented with the following contents:

contentss

The contents of the box are as follows:

  • The meter itself;
  • a long (~1.2m) pair of Cat IV leads with very sharp points;
  • matching insulated alligator clip adaptors;
  • a K-type thermocouple;
  • a printed Getting Started manual, and the complete manual on CDROM;
  • a single, universal getting started sheet – explains how to remove battery isolation tabs.

However, a carry case was not included. Considering the cost of the meter here (Au$550 + tax), one would have expected a case. On the other hand, if you/your workplace can afford a 233, you can pay for your own case. So there’s two angles to the case perspective.

It is good to see that there isn’t too much of a printer manual, the less paper used the better. As others have said, if you have one of these meters the manual isn’t necessary apart from checking the specifications, and the same applied to myself. Thoughtfully the meter is supplied and fitted with 5 x AA Duracell alkaline cells, three in the meter body and two in the display unit. All one needs to do is pull out the plastic tabs from the battery compartments, and you’re ready to go.

Physically the unit does not disappoint. Made in the USA. First class. Another solid Fluke design, clean lines, and a great fit and finish. Futhermore it is of a good weight, so you could always bang in a nail with it, or the pointy-head boss. The exterior has the rubber-moulded housing which is not removable, however this would be recommended for the target market – as the 233 would be more of a field work than a test-bench instrument. However, if you do sit it on the bench with the tilting bail, you can still operate it with one hand as it has enough friction to stay put. It is also good to see that the box and packaging are cardboard which is easily recycled.

After flicking the meter on the first thing to do was remove the display, plug in the thermocouple, and toss the body into the freezer:

freezer-tests

Even with the meter in the freezer, I could still move the display around 1.5 meters away and it still received the data signal. Notice how the display is on the freezer door – it is magnetic. Immediately the benefits of the remote display come to mind. You can always have the display right where you want it, and the meter where it needs to be… it’s win-win. After showing it to my auto-electrician friend, she didn’t want to give it back.

The ability to set up a meter in a less than perfectly safe environment and take the display away is almost priceless. Furthermore, the backlight is a nice even blueish colour, and times out after around forty seconds. Whilst in the kitchen, I tested out the external temperature of my tea:

teas

Using the meter in general is very simple, you can hold it in one hand and select all of the functions with your thumb. Having the yellow shift key makes changing between associated readings very simple, for example after reading AC voltage:

241vacs

Then pressing the shift key changes to frequency:

50-hzss

The meter has several useful indication functions – while working with high voltages the triangular market is illuminated; when changing to temperature you are prompted with “OPEN” for the thermocouple, and changing to current you are prompted with “LEAD” to change sockets. It is obvious after a short period of time this was designed by engineers for engineers, and not made to a ‘price’. Although this is not an electronics multimeter, it still has quite a few ranges that would suit at a pinch. Plus the one-touch data hold, minimum and maximum functions are included as with other top-end Flukes. Hopefully someone at Fluke is working on a remote display version of their 87V.

Now that I have had this meter for just over five months, it has already become a worthwhile addition to my bench. For the kind of work I do, it has already replaced another multimeter, my old frequency counter and thermometer. The ranges are quite useful, and the continuity beeper is in the display not the body. According to the manual the 233 is rated for a one meter drop onto any of the six surfaces. Out of respect to the meter I will not throw it into a river or from a moving car. The other factor that prevents me from going to such extremes is the clear plastic over the LCD – there is a small amount of ‘give’ or flexibility in that area. Otherwise the 233 is as solid as they come.

The specifications can be found in detail in the manual here, however a quick glance shows:

Range                                                             Accuracy

AC voltage: 0.1mV ~ 1000V                      1~2%+3

AC current: 1mA ~ 10A                               1.5%+3

DC voltage: 0.1mV ~ 1000V                     0.25%+2

DC current: 1mA ~ 10A                               1.0%+3 ** no microamperes

resistance: 0.1 ~ 40 meg-ohm                   0.9~1.5%+2

frequency:  0.01 Hz ~ 50 kHz                    0.1%+2

capacitance: 1nF to 9999 uF                     1.9%+2

temperature: -40 ~ 400 degrees Celsius     1%+10

And there is also a diode test and continuity beeper function. Interestingly enough, I discovered by accident that the frequency counter function was slightly underrated. Some more testing showed it was good for up to 99.48 kHz:

233_freq

Not bad at all. However as with the many pros, there are  a few cons to using this meter. The auto-zero time of the display is a little slow, sometimes it can take two seconds. That doesn’t sound like much, but when you’re measuring many components the time adds up. And the LCD is not protected as well as expected, you can push into it with your finger. For a Fluke meter, one would expect it to be much more solid – if the display unit fell from a height and landed on something pointy with the display facing down, it would be ruined. So be careful if you have one.

Furthermore, the battery life is around eight to ten weeks of “daily use” (perhaps seven hours a week, usually with the backlight on). Some have said this is bad, however my opinion is that the convenience of the remote display makes up for the shorter battery life.

However at the end of the day – this is a great tool. Being able to measure something outside your field of vision, and having the results in front of you is incredibly useful. You could achieve the same functions by using a meter with a PC interface, but that can be overkill and time-consuming to set up. So if the specifications of the 233 meet your needs, this is a great tool that will serve you very well.

The Fluke 233 Remote Display True RMS Multimeter is available from your local element-14 or Fluke distributor.

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.

[Disclaimer – the Fluke 233 is a review sample made available by Fluke via element-14]

Posted in 233, fluke, learning electronics, product review, test equipmentComments (6)

Kit review: Freetronics 16×2 LCD Arduino Shield

Hello everyone

This kit has now been discontinued, however Freetronics now have a great LCD+Keypad Shield.

Today we examine their latest kit, the “16×2 LCD Arduino Shield“. This is a very easy to construct, yet useful tool for those experimenting, prototyping and generally making things with their Arduino-based systems.  The purpose of the shield is to offer easy access to a 16 x 2 character LCD module, and also the use of five buttons – connected to an analog input using the resistor ladder method. The kit comes packaged very well, and includes not only detailed printed instructions in colour, but also the full circuit schematic:

contentsss

It is nice to see such a high level of documentation, even though most people may not need it – there is generally someone who does. Sparkfun – get the hint. All the parts are included, and for the first time in my life the resistors were labelled as well:

partsss1

So being Mr Pedantic I followed the instructions, and happily had the components in without any troubles. The next step was the Arduino shield pins – the best way to solder these is to insert into your Arduino board, drop the shield on top then solder away as such:

shieldpinsss

And finally, bolting on the LCD whilst keeping the header pins for the LCD in line. Some people may find the bolt closest to D0 interferes with the shield pin, so you can insert the bolt upside down as I have. Remember to not solder the LCD pins until you are happy it is seated in correctly:

lcdtopcbss

Once you are satisfied the pins are lined up and sitting in their required position – solder them in, tighten your nuts and that’s it:

finishedss

The contrast of the LCD in real life is better than shown in the photo above – photographing them is a little difficult for me. However once assembled, using the shield is quite easy. If your LCD doesn’t seem to be working after your first sketch, adjust the contrast using the potentiometer. The LCD is a standard HD44780-interface model, and wired in to use a 4-bit parallel data interface. If using these types of LCD is new to you, perhaps visit this article then return. Our shield uses the pins: A0 and D4~D9.

One uses the standard Arduino liquidCrystal library with this LCD, and the function parameters to use are as follows:

The buttons are read using analog pin A0. Use the following sketch to find the values returned by the analogRead function:

and a quick video of this in action:

Now that we know the values returned for each button, we can take advantage of them to create, for example, a type of menu system – or some sort of controller. In the second example, we have used a modified TwentyTen with a DS1307 real-time clock IC to make a digital clock. The buttons on the LCD shield are utilised to create a user-friendly menu to set the clock time.

You can download the demonstration sketch from here.

In general this is an excellent kit, and considering the price of doing it yourself – good value as well. To get your hands on this product in kit or assembled form – visit Freetronics’ website, or your local reseller.

Remember, if you have any questions about these modules please contact Freetronics via their website. Higher resolution images available on flickr.

[Note – the kit assembled in this article was received from Freetronics for review purposes]

Posted in arduino, kit review, LCDComments (6)

Tutorial: Arduino and monochrome LCDs

Please note that the tutorials are not currently compatible with Arduino IDE v1.0. Please continue to use v22 or v23 until further notice. 

This is chapter twenty-four of a series originally titled “Getting Started/Moving Forward with Arduino!” by John Boxall – A tutorial on the Arduino universe.

The first chapter is here, the complete series is detailed here.

Welcome back fellow arduidans!

The purpose of this article is to summarise a range of affordable monochrome liquid-crystal display units that are available to work with our Arduino; and to replace the section about LCDs in chapter two of this series. We will first examine some fixed-character and then graphical LCD units in this article. So let’s go!

Fixed-character LCD modules

When shopping around for LCD modules, these will usually be the the most common found in retail outlets. Their size is normally measured by the number of columns and rows of characters in the display. For example, the three LCDs below are 8×2, 16×2 and 20×4 characters in size:

lcdtypesss

Currently, most LCDs should have a backlight of some sort, however you may come across some heavily-discounted models on (for example) eBay that are not. Character, background and backlight colours can vary, for example:

backlitsss

Interfacing these screens with our Arduino boards is very easy, and there are several ways to do so. These interface types can include four- and eight-bit parallel, three-wire,  serial, I2C and SPI interfaces; and the LCD price is usually inversely proportional to the ease of interface (that is, parallel are usually the cheapest).

Four-bit parallel interface

This is the cheapest method of interface, and our first example for this article. Your LCD will need a certain type of controller IC called a Hitachi HD44780 or compatible such as the KS0066. From a hardware perspective, there are sixteen pins on the LCD. These are usually in one row:

16pinsss

… or two rows of eight:

2by8pinsss

The pin labels for our example are the following:

  1. GND
  2. 5V (careful! Some LCDs use 3.3 volts – adjust according to LCD data sheet from supplier)
  3. Contrast
  4. RS
  5. RW
  6. Enable
  7. DB0 (pins DB0~DB7 are the data lines)
  8. DB1
  9. DB2
  10. DB3
  11. DB4
  12. DB5
  13. DB6
  14. DB7
  15. backlight + (unused on non-backlit LCDs) – again, check your LCD data sheet as backlight voltages can vary.
  16. backlight GND (unused on non-backlit LCDs)

As always, check your LCD’s data sheet before wiring it up.

Some LCDs may also have the pinout details on their PCB if you are lucky, however it can be hard to decipher:

Now let’s connect our example 16×2 screen to our Arduino using the following diagram.

Our LCD runs from 5V and also has a 5V backlight – yours may differ, so check the datasheet:

4bitparallel2

(Circuit layout created using Fritzing)

Notice how we have used six digital output pins on the Arduino, plus ground and 5V. The 10k ohm potentiometer connected between LCD pins 2, 3 and 5 is used to adjust the display contrast. You can use any digital out pins on your Arduino, just remember to take note of which ones are connected to the LCD as you will need to alter a function in your sketch. If your backlight is 3.3V, you can use the 3.3V pin on the Arduino.

From a software perspective, we need to use the LiquidCrystal() library. This library should be pre-installed with the Arduino IDE. So in the start of your sketch, add the following line:

Next, you need to create a variable for our LCD module, and tell the sketch which pins are connected to which digital output pins. This is done with the following function:

The parameters in the brackets define which digital output pins connect to (in order) LCD pins: RS, enable, D4, D5, D6, and D7.

Finally, in your void setup(), add the line:

This tells the sketch the dimensions in characters (columns, rows) of our LCD module defined as the variable lcd. In the following example we will get started with out LCD by using the basic setup and functions. To save space the explanation of each function will be in the sketch itself. Please note that you do not have to use an Arduino Mega – it is used in this article as my usual Arduino boards are occupied elsewhere.

And here is a quick video of the example 24.1 sketch in action:

There are also a some special effects that we can take advantage of with out display units – in that we can actually define our own characters (up to eight per sketch). That is, control the individual dots (or pixels) that make up each character. With the our character displays, each character is made up of five columns of eight rows of pixels, as illustrated in the close-up below:

pixels

In order to create our characters, we need to define which pixels are on and which are off. This is easily done with the use of an array (array? see chapter four). For example, to create a solid block character as shown in the image above, our array would look like:

Notice how we have eight elements, each representing a row (from top to bottom), and each element has five bits – representing the pixel column for each row. The next step is to reference the custom character’s array to a reference number (0~7) using the following function within void setup():

Now when you want to display the custom character, use the following function:

where 0 is the memory position of the character to display.

To help make things easier, there is a small website that does the array element creation for you. Now let’s display a couple of custom characters to get a feel for how they work. In the following sketch there are three defined characters:

And here is a quick video of the example 24.2 sketch in action:

So there you have it – a summary of the standard parallel method of connecting an LCD to your Arduino. Now let’s look at the next type:

Three-wire LCD interface

If you cannot spare many digital output pins on your Arduino, only need basic text display and don’t want to pay for a serial or I2C LCD, this could be an option for you. A 4094 shift register IC allows use of the example HD44780 LCD with only three digital output pins from your Arduino. The hardware is connected as such:

twilcd

And in real life:

exam24p3ss

From a software perspective, we need to use the LCD3Wire library, which you can download from here. To install the library, copy the folder within the .zip file to your system’s \Arduino-2x\hardware\libraries folder and restart the Arduino IDE. Then, in the start of your sketch, add the following line:

Next, you need to create a variable for our LCD module, and tell the sketch which of the 4094’s pins are connected to which digital output pins as well as define how many physical lines are in the LCD module. This is done with the following function:

Finally, in your void setup(), add the line:

The number of available LCD functions in the LCD3wire library are few – that is the current trade-off with using this method of LCD connection … you lose LCD functions but gain Arduino output pins. In the following example, we will demonstrate all of the available functions within the LCD3Wire library:

And as always, let’s see it in action. The LCD update speed is somewhat slower than using the parallel interface, this is due to the extra handling of the data by the 4094 IC:

Now for some real fun with:

Graphic LCD modules

(Un)fortunately there are many graphic LCD modules on the market. To keep things relatively simple, we will examine two – one with a parallel data interface and one with a serial data interface.

Parallel interface

Our example in this case is a 128 by 64 pixel unit with a KS0108B parallel interface:

glcdparallelss

For the more technically-minded here is the data sheet. From a hardware perspective there are twenty interface pins, and we’re going to use all of them. For breadboard use, solder in a row of header pins to save your sanity!

This particular unit runs from 5V and also has a 5V backlight. Yours may vary, so check and reduce backlight voltage if different.

You will again need a 10k ohm potentiometer to adjust the display contrast. Looking at the image above, the pin numbering runs from left to right. For our examples, please connect the LCD pins to the following Arduino Uno/Duemilanove sockets:

  1. 5V
  2. GND
  3. centre pin of 10k ohm potentiometer
  4. D8
  5. D9
  6. D10
  7. D11
  8. D4
  9. D5
  10. D6
  11. D7
  12. A0
  13. A1
  14. RST
  15. A2
  16. A3
  17. A4
  18. outer leg of potentiometer; connect other leg to GND
  19. 5V
  20. GND

A quick measurement of current shows my TwentyTen board and LCD uses 20mA with the backlight off and 160mA with it on. The display is certainly readable with the backlight off, but it looks a lot better with it on.

From a software perspective we have another library to install. By now you should be able to install a library, so download this KS0108 library and install it as usual. Once again, there are several functions that need to be called in order to activate our LCD. The first of these being:

which is placed within void setup(); The parameter sets the default pixel status. That is, with NON_INVERTED, the default display is as you would expect, pixels off unless activated; whereas INVERTED causes all pixels to be on by default, and turned off when activated. Unlike the character LCDs we don’t have to create an instance of the LCD in software, nor tell the sketch which pins to use – this is already done automatically. Also please remember that whenever coordinates are involved with the display, the X-axis is 0~127 and the Y-axis is 0~63.

There are many functions available to use with the KS0108 library, so let’s try a few of them out in this first example. Once again, we will leave the explanation in the sketch, or refer to the library’s page in the Arduino website. My creative levels are not that high, so the goal is to show you how to use the functions, then you can be creative on your own time. This example demonstrate a simpler variety of graphic display functions:

Now let’s see all of that in action:

You can also send normal characters to your KS0108 LCD. Doing so allows you to display much more information in a smaller physical size than using a character  LCD. Furthermore you can mix graphical functions with character text functions – with some careful display planning you can create quite professional installations. With a standard 5×7 pixel font, you can have eight rows of twenty-one characters each. Doing so is quite easy, we need to use another two #include statements which are detailed in the following example. You don’t need to install any more library files to use this example. Once again, function descriptions are in the sketch:

Again,  let’s see all of that in action:

If you’re looking for a very simple way of using character LCD modules, check this out.

LEDborder

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 arduino, education, LCD, LCD-00710, learning electronics, lesson, microcontrollers, tutorialComments (52)

Kit Review – adafruit industries Ice Tube clock v1.1

Hello readers

Today we examine a kit that perhaps transcends from general electronic fun and games into the world of modern art – the adafruitIce Tube” clock.

What is an Ice Tube clock? Before LCDs (liquid-crystal displays) were prevalent another form of display technology was popular – the vacuum-fluorescent display (or VFD). This clock uses a VFD originally manufactured in the former Soviet Union (link for the kids) or Russia (I think mine is date-stamped January 1993). This particular VFD contains a series of seven-segment digits and a dot, which allow the display of time in a bright and retro fashion.

Since this kit was released I had always desired one, however my general parsimonious traits and the wavering exchange rate against the US dollar kept my spending in check. But lately my wallet was hit by a perfect storm: the Australian dollar hit parity with the greenback, adafruit had a discount code and I felt like spending some money – so before the strange feelings passed I ordered a kit post-haste.

Sixteen slow, hot days later the box arrived. I must admit to enjoying a good parcel-opening:

packagingss

As always, the packaging was excellent and everything arrived as it should have. But what was everything?

boxcontentsss

Included is the anti-static bag containing the PCB and general components, a bag with the laser-cut acrylic pieces to assemble the housing, another bag with the housing fasteners and the back-up coin cell for the clock, a mains adaptor, and finally another solid cardboard box containing the classic display unit – albeit with the following sensible warning:

warningss

And finally the Russian IV-18 display tube:

tuberulerss

The tube is a fascinating piece of work, certainly a piece of perfect retro-technology and a welcome addition to my household. Assembling the clock will not be a fast process, and in doing so I recommend reviewing the detailed instructions several times over at the adafruit website. Furthermore, it is a good idea to identify, measure and line up the components ready for use, to save time and confusion along the way. Your experience may vary, however this kit took around three hours for me to construct.

Normally with most kits you can just solder the components in any order, however it is recommended you follow the instructions, as they are well written and allow for testing along the way. For example, after installing the power regulator, you can check the output:

firsttestss

At this stage, you can test your progress with the piezo beeping at power-on:

pcb2ss

These mid-construction tests are a good idea as you can hopefully locate any problems before things get out of hand. Another item to be careful with is the PLCC socket for the Maxim MAX6921 VFD driver IC (second from the left):

pcb3ss

However with time and patience there is no reason why you would have any problems. Once the main PCB is completed, the next item is the end PCB which connects to the VFD:

endpcbss

At this point it is a good time to have a break and a bit of a stretch, as you need all your patience for soldering in the VFD. Before attempting to do so, try and carefully straighten all the wires from the VFD so they are parallel with each other. Then using the adafruit instructions, make sure you have the tube wires lined up with the correct hole on the PCB:

endpcb2ss

After I had the leads through the correct holes on the PCB, trimming the leads made things easier:

endpcb3ss

It is also a good idea to check the gap between the VFD and the PCB is correct, by checking the fit within the housing:

testfitss

And after much patience, wire pulling with pliers, and light soldering –  the VFD was married to the PCB:

endpcb4ss

So now the difficult soldering work has been completed and now it was time for another test – the big one… does it all work?

alivess

Yes, yes it does. *phew* The low brightness is normal, as that is the default level set by the software. Please note: if you run your VFD without an enclosure that you must be careful of the high voltages on the right-hand side of the PCB and also the VFD PCB. If you test your VFD in this manner, don’t forget to allow ten minutes for the voltage to return to a safe level after removing the power supply. If you have been following the instructions (I hope so!) there is some more soldering to do, after which you can put away your soldering iron.

Now to remove the liner from the acrylic housing pieces and put it all together. Be very careful not to over-tighten the bolts otherwise you will shatter the housing pieces and be cranky. If all is well, you’re finished clock will appear as such:

tothisss

The clock in use:

runningss1

And finally, our ubiquitous video demonstration:

VFDs can lose their brightness over the years, and can be difficult to replace – so if you want many, many years of retro-time it would be smart to buy an extra tube from adafruit with your kit, or a modified DeLorean.

Overall, this was an interesting and satisfying kit to assemble. Not for the beginner, but if you have built a few easier kits such as  the “TV-B-Gone” with success, the Ice Tube clock will be within your reach. Furthermore, due to the clear housing, this kit is a good demonstration of your soldering and assembly skills. High resolution images are available on flickr.

You can purchase the kit directly from adafruit industries. 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.

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

Posted in adafruit, clocks, ice tube clock, IV-18, kit review, VFDComments (3)

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