Introduction: Radio Controlled Stopwatch
As a teacher and member of various sporting organisations, I have observed various different timing systems, from the traditional stand-alone stopwatches to more sophisticated (and very expensive) co-ordinated systems that simultaneously time, then record race data. The system is still under construction. I have commenced writing this Instructable early as I have already discovered some pitfalls and shortcuts!.
Step 1: Equipment - Shopping List
Starter GUN Transmitter
- nRF24L01 2.4GHz Radio/Wireless Transceivers.
- Arduino Uno
- Wii gun controller with momentary button attached
- 12 volt piezo speaker+ voltage booster
- camera flash +opto-coupler
- Five AAA rechargeable batteries
- enclosure + jumpers + protoboard , 10uF capacitor
- capacitor 47 uF capacitor .33 uF 3.3 volt regulator
Six Identical Receiver Stopwatches
- Arduino Uno
- momentary stop button
- reset button (can't be knocked mid-race!)
- 16 x 2 LCD module
- 5 permanent AAA rechargeable batteries.
- on/off barrel key switch (can't be switched off mid-race!)
- Red LED (RSSI indicator) 330 ohm resistor
- enclosure + jumpers + protoboard (see above) lanyardeye bolt
Step 2: Prepare Radios and Attach to Uno
- breadboard with a momentary switch
- all equipment from step 1
- soldering equipment and lots of different coloured wires
- male headers (optional if not using jumpers)
- all equipment from step one.
- go to maniacbug and read all preliminary info on 2.4 ghz radios.
- On both radios, solder all coloured wires (or cut off jumpers with male end attached) onto radio module headers - try and use maniacbug colour coding above.
- HINT: Check for short circuits
- HINT: Attach 10uf capacitor to VCC and Gnd, close as possible to the radio- check polarity.
- Set up breadboard and attach momentary button to digital pin 7 and 10 k pullup resistor to gnd. Attach 5v to other side of momentary switch. Diagram.
- HINT: To ensure button works Try running the arduino 'button' sketch before adding radio module
- Attach radio headers onto UNO. Pin allocations are:
- Pin 9 orange
- Pin 10 yellow
- Pin 11 blue
- Pin 12 violet
- Pin 13 green
- Gnd black
- 3.3v red
Step 3: Attach the Receiver/Stopwatch
Use this guide to Solder wires onto LCD shield .
Hint: Pins 4, 5, 6, 7, 8, 9 do not need any soldering but should be checked with a multimeter to ensure that the pins are correct for the sketches you'll use. eg On pin 4, check continuity from arduino pin 4 to D4 on LCD. Some modules don't have the same pin allocations as the way I have stated below...
- Pin 3 RADIO CE (orange) solder onto LCD shield
- Pin 4 LCD D4 pin to digital pin 4
- Pin 5 LCD D5 pin to digital pin 5
- Pin 6 LCD D6 pin to digital pin 6
- Pin 7 LCD D7 pin to digital pin 7
- Pin 8 LCD RS pin to digital pin 8
- Pin 9 LCD Enable pin to digital pin 9
- Pin 10 RADIO CSN (Yellow) solder onto LCD shield
- Pin 11 RADIO SCK (Green) solder onto LCD shield
- Pin 12 RADIO MOSI (Blue) solder onto LCD shield
- Pin 13 RADIO MISO (Violet) solder onto LCD shield
- 5 Volt Momentary "Stop" button with 10k pullup resist or to Gnd
- Gnd RADIO GND (black) solder onto LCD shield.
- A1 proto button on breadboard. attach 10K resistor to earth side of button.
- 3.3 Volt RADIO VCC (red)
- HINT: DO NOT CONNECT 5 v TO RADIO!!!!
- HINT: 5volt VCC not needed for prototyping.
- HINT: Hardwire the momentary button to a GND rail on a proto board, ready to go into enclosure.