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…
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.
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.
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).
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.
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 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.
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.
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.
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.
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). And finally, the:
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. 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.
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.
Posted by Posterous on January 31, 2012 in News.