Tag Archive | "temperature"

Review – Freetronics Module Family


In this article we examine a new range of eleven electronic modules from Freetronics. When experimenting with electronics or working on a prototype of a design, the use of electronic components in module form can make construction easier, and also reduce the time between thoughts and actually making something 🙂 So let’s have a look at each module in more detail…

PoE Power Regulator – 28V

This is a tiny switchmode voltage regulator with two uses – the first being regulation of higher voltage up to 28V carried via an Ethernet cable to a Freetronics Ethernet shield or EtherTen to power the board itself. The PCB is designed to drop into the shield or EtherTen as such:

… and converts the incoming voltage down to 7V which can be regulated by the EtherTen’s inbuilt regulator. The second use of this board is a very handy power supply for breadboarding or other experimentation. By bridging the solder pads on the rear of the board, the output is set to 5V DC, as such:

Note the addition of the header pins, which make insertion into a breadboard very easy – so now you have a 5V 1A DC power supply. For more information visit the product page.

N-MOSFET Driver/Output Module

This module contains an On Semi NTD5867NL MOSFET which allows the switching of a high current and voltage line – 60V at up to 20A – with a simple Arduino or other MCU digital output pin. The package is small and also contains enlarged holes for direct connection of high-current capability wire:

The onboard circuitry includes a pull-down resistor to ensure the MOSFET is off by default. For more information see the product page.

Logic Level Converter Module

This is a very simple and inexpensive method to interface 3.3V sensors to 5V microcontrollers in either direction.The module contains four independent channels, as shown in the image below:

However you can interface any low or higher voltage, as long as you connect the low and high voltages to the correct sides (marked on the PCB’s silk screen). For more information please visit the product page.


Surprisingly this module contains a RGB LED module (red, green and blue LEDs) which is controlled by a WS2801 constant-current LED driver IC. This module is only uses two digital output pins, and can be daisy-chained to control many modules with the same two pins. The connections are shown clearly on the module:

The WS2801 controller IC is on the rear:

There are several ways to control the LEDs. One way is using the sketch from the product home page, which results with the following demonstration output:

Or there is a unique Arduino WS2801 library available for download from here. Using the strandtest example included with the library results with the following:

During operation the module used less than 24 mA of current and therefore can happily run from a standard Arduino-type board without any issues. For more information please visit the product page.

TEMP Temperature Sensor Module

This module allows the simple measurement of temperature using the popular DS18B20 temperature sensor. You can measure temperatures between -55° and 125°C with an accuracy of +/- 0.5°C. Furthermore as the sensor uses the 1-wire bus, you can daisy-chain more than one sensor for multiple readings in the one application. The board is simple to use, and also contains a power-on LED:

Using the demonstation Arduino sketch from the product page results in the following output via the serial monitor:

Using this module is preferable to the popular Analog Devices TMP36, as it has an analogue output which can be interfered with, and requires an analogue input pin for each sensor, whereas this module has a digital output and as mentioned previously can be daisy-chained. For more information please visit the product page.

Humidity and Temperature Sensor Module

For the weather-measuring folk here is a module with temperatures and humidity. Using the popular DHT22 sensor module the temperature range is -4°C to +125°C with an accuracy of +/- 0.5°C, and humidity with an accuracy of between two and five percent. Only one digital input pin is required, and the board is clearly labelled:

There is also a blue power-on LED towards the top-right of the sensor. Using the module is quite simple with Arduino – download and use the example sketch included in the sensor library you can download from here. For the demonstration connect the centre data pin to Arduino digital two. Here is an example of the demonstration output:

Although the update speed is not lightning-fast, this should not be an issue unless you’re measuring real-time external temperature of your jet or rocket. For more information please see the product page.

Shift Register/Expansion Module

This board uses a 74HC595 serial-in parallel-out shift register which enables you to control eight digital outputs with only three digital pins, for example:

You can daisy-chain these modules to increase the number of digital outputs in multiples of eight, all while only using the three digital output pins on your Arduino or other microcontroller. For more information about how to use shift registers with Arduino systems, read our detailed tutorial. Otherwise for more information about the module please visit the product page.

Hall Effect Magnetic and Proximity Sensor Module

This module contains a sensor which changes output from HIGH to LOW when a magnetic presence is detected, for example a magnet. The board also has an LED which indicates the presence of the magnet to aid in troubleshooting:

Using this module and a small magnet would be an easy way to create a speedometer for a bicycle, the module is mounted to the fork, and the magnet on the rim of the front wheel. For more ideas consider the speedometer project in this tutorial. Otherwise for more information about this module please visit the product page.

Microphone Sound Input Module

This module performs two functions – it can return the sound pressure level (SPL) or the amplified audio waveform from the electret microphone. The LED (labelled “DETECT”) on the board visually displays an approximation of the SPL – for example:

… however the value can be returned by using an analogue input pin on an Arduino (etc). to return a numerical value. To do this connect the SPL pin to the analogue input. The MIC pin is used to take the amplified output from the microphone, to be processed by an ADC or used in an audio project. For more information please visit the product page.

Light Sensor Module

This module uses the TEMT6000 light sensor which returns more consistent values than can be possible using a light-dependent resistor. It outputs a voltage from the OUT pin that is proportional to the light level. The module is very small:

Use is simple – just measure the value returned from the OUT pin using an analogue input pin on your Arduino (etc). For more information please visit the product page. And finally, the:

Sound and Buzzer Module

This module contains a piezoelectric element that can be used to generate sounds (in the form of musical buzzes…):

Driving the buzzer is simple, just use pulse-width modulation. Arduino users can find a good demonstration of this here. Furthermore, as piezoelectric elements can also generate a small electrical current when vibrated, they can be used as “shock” detectors by measuring the voltage across the terminals of the element. The procedure to do this is also explained clearly here.

Now for a final demonstration – we use the light sensor to demonstrate making some noise with the buzzer module:

One final note I would like to make is that the design and construction quality of each module is first rate. The PCBs are strong, and the silk-screening is useful and descriptive. If you find the need for some or all of the functions made available in this range, you could do worse by not considering a Freetronics unit. Finally, although this has only been a short introduction to the modules for now, we will make use of them in later projects.

The modules are available directly from Freetronics or through their network of resellers.

Disclaimer – Modules reviewed in this article are a promotional consideration made available by Freetronics

Have fun and keep checking into tronixstuff.com. Why not follow things on twitter, Google+, 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, freetronics, learning electronics, microcontrollers, modules, reviewComments (0)

Moving Forward with Arduino – Chapter 14 – XBee introduction

Learn how to use XBee wireless data transceivers with Arduino. This is part of a series originally titled “Getting Started with Arduino!” by John Boxall – A tutorial on the Arduino universe. The first chapter is here, the complete series is detailed here.

Updated 02/03/2013

We will examine the Series 1 XBee wireless data transceivers from Digi in the USA. Although in the past we have experimented with the inexpensive 315MHz transmit/receive pair modules (chapter 11), they have been somewhat low in range and slow with data transmission. The XBee system changes this for the better.

First of all, what is an Xbee module? It is a very small piece of hardware that can connect wirelessly with another using the Zigbee communication protocols. There are many different models, including aerial types and power outputs. In this tutorial we’re using Series One XBees.

From Wikipedia, Zigbee is:

ZigBee is a specification for a suite of high level communication protocols using small, low-power digital radios based on the IEEE 802.15.4-2003 standard for wireless home area networks (WHANs), such as wireless light switches with lamps, electrical meters with in-home-displays, consumer electronics equipment via short-range radio. The technology defined by the ZigBee specification is intended to be simpler and less expensive than other WPANs, such as Bluetooth. ZigBee is targeted at radio-frequency (RF) applications that require a low data rate, long battery life, and secure networking.

Phew. For this chapter I will try and keep things as simple as possible to start off with. Here is an image of a typical Xbee unit:

Note that the pin spacing is small than 2.54mm, so you cannot just drop these into a breadboard. However for the purposes of our experimenting more equipment is needed. Therefore I am making use of this retail package from Sparkfun:


This bundle includes two Xbee modules, an Xbee shield to connect one of the modules to an Arduino Uno-style board. When it comes time to solder the sockets into your shield, the best way is to insert them into another shield that is upside down, then drop the new shield on top and solder. For example:


Finally, the bundle also includes a USB Explorer board, which allows us to connect one Xbee to a personal computer. This allows us to display serial data received by the Xbee using terminal software on the PC. One can also adjust certain Xbee hardware parameters by using the explorer board such software.

Let’s do that now. You will need some terminal software loaded on your computer. For example, Hyperterminal or Realterm. Plug an Xbee into the explorer board, and that into your PC via a USB cable. Determine which port (for example COM2:) it is using with your operating system, then create a new terminal connection. Set he connection to 9600 speed, 8 bits, no parity, 1 stop bit and hardware flow control. For example, in Hyperterminal this would look like:

Once you have established the connection, press “+++” (that is, plus three times, don’t press enter) and wait. The terminal screen should display “OK”. This means you are in the XBee configuration mode, where we can check the settings and change some parameters of the module. Enter “ATID” and press enter. The terminal window should display a four-digit number, which is the network ID of the module. It should be set by default to 3332. Unless you plan on creating a huge mesh network anytime soon, leave it be. To be sure your modules will talk to each other, repeat this process with your other XBee and make sure it also returns 3332. However as this is the default value, they should be fine.

Now for our first example of data transmission, insert one Xbee into the explorer module, and the other into the Xbee shield. With regards to the Xbee shield – whenever it is connected to an Arduino board and you about to upload a sketch, look for a tiny switch and change it to DLINE from UART. Don’t forget to change it back after uploading the sketch. See:


We are going to use the two Xbee modules as a straight, one-way serial line. That is, send some data out of the TX pin on the transmit board, and receive it into the terminal on the PC. Now upload this sketch into your Arduino board. This is a simple sketch, it just sends numbers out via the serial output. Then set the switch on the shield back to UART, and reset the board. If you can, run this board on external power and put it away from the desk, to give you the feeling that this is working 🙂

Note: More often that not one can purchase AC plug packs that have USB sockets in them, for charging fruity music players, and so on.


Or you might have received one as a mobile phone charger. These are great for powering Arduino boards without using a PC. Now ensure your explorer module is plugged in, and use the terminal software to connect to the port the explorer is plugged into. After connecting, you should be presented with a scrolling list of numbers from 0 to 99, as per example 14.1 sketch:


How did you go? Sometimes I used to get the COM: ports mixed up on the PC, so that is something to keep track of. If you are powering both Xbees from your PC using USB cables, double-check the terminal software is looking at the explorer board, as an Arduino transmitting serial data through an Xbee shield will still send the same data back to the PC via USB.

Now that we have sent data in one direction, we can start to harness the true power of Xbees – they are transceivers, i.e. send and receive data. Next, we’ll create an on-demand temperature and light-level sensor. Our arduino board will have a temperature sensor and a light-dependent resistor, and using the terminal on the computer, we can request a temperature or light-level reading from the remote board. More about temperature sensors in chapter two. First of all, the remote board hardware setup:


… and the schematic:



It never hurts to elevate your other Xbee:


For the PC side of things, use the explorer board and USB cable. Here is the sketch. It is quite simple. The remote board ‘listens’ to its serial in line. If it receives a “1”, it reads the temperature, converts it to Celsius and Fahrenheit, and writes the result to its serial out line, which is sent over our Xbee data bridge and received by the host computer. A “2” will result in the analogue value of the photocell to be sent back as a “light level”. Once again we use the terminal software to control the system.  Here is a quick video of the terminal in action:

The speed is quite good, almost instantaneous. By now hopefully you can see how easy it is to end some data backwards and forwards over the ether. The range is only limited by the obstacles between the Xbee transceivers and the particular power output of each model. With example 14.2, there were two double-brick walls between them. Furthermore, we can build fully computer-independent systems that can talk to each other, such as more portable remote controls, or other data-gathering systems. In the next few chapters, sooner rather than later.


Have fun and keep checking into tronixstuff.com. Why not follow things on twitter, Google+, 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, learning electronics, lesson, microcontrollers, RTL-11445, tutorial, wireless, WRL-09819, WRL-11215, xbeeComments (9)

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