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Sensors and Wiring

The sensors and exact setup used by your microcontroller is completely up-to you - However the following is our recommendation. 

Microcontroller

Arduino Uno, Arduino Nano or similar.  ~£7 for an identical clone  ~£21 for a 'genuino'
These can often be bought on Amazon/eBay etc. much cheaper than on the Arduino website - just be sure to check the reviews that they are identical and work out of the box. Some cheaper 'clones' require drivers to be installed. 

Power Supply

The Arduino will require a power supply. For Greenpower cars not using their Arduino as a speed controller a 9V battery can be used. If the Arduino is being used as a controller then to meet the specification the power must come from the main race batteries - This is a little more complex and will require a sturdy transformer to convert either the 24V/12V to 9V/5V.  The transformer will need to be able to deal with the change in voltage over a race plus the noise from the circuitry. 

Bluetooth module

A Bluetooth module is required to send the data to the app on the phone. 
HC-06 modules are available for a couple of pounds and work fairly well. 
If you will have a large amount of material between the module and the phone then it may be better to upgrade to a HM10 module which uses Bluetooth 4.0 (If the phone supports it) and hence has a better range. Make sure NOT to buy a HM10-A as this will not work - some cheaper sellers on Amazon will send you these 'by mistake' so check the reviews. 

Hall-effect current sensor ~ £17

This sensor allows us to measure the instantaneous current consumption and thus enables us to calculate the Amphours used by the car. A good option is the LEM LA series closed loop current sensor - 130A. The current drawn by a Greenpower on a relay can exceed 100A when accelerating from rest hence the 130A model is recommended. If a controller is being used for accelerating from rest then a cheaper lower current model may be suitable.


Measuring voltage is also very important; the simplest way to achieve this is to make a potential divider using two resistors. See the wiring diagram for info. 

RPM and temperature sensors (TMP36 are very easy to use) are an optional extra. 

Wiring it all up

Diagram coming soon..


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