Stopwatch react on 2.4GHz start/stop signals - works with famous game GraviTrax from Ravensburger. This is my private work. I am not connected in any way to Ravensburger. This is not official supported.
First prototype and development board:
Final board, mounted on wood plate with battery holder - used by my kids:
Board is based on ATMEGA328 microcontroller with XN297L chip as radio device. I decided to start with ready to use module from DreamLnk. Used display is [OLED 128x32 pixel with SSD1306 controller] (https://www.lcsc.com/product-detail/OLED-Display_HS-HS91L02W2C01_C5248081.html). On the board there is also a ST M24C32 footprint - but so far this EEPROM isn't used. All other parts are standard parts - should not really matter which are being used.
Folders:
- ./Board: current schematic and board in EasyEDA format
- ./Board v0.1: first version produced
- ./GTStoppuhr: Microchip studio for AVR solution
- ./xn297l_analyzer: Salea Logic 2 high level analyzer to debug XN297L
- the eeprom isn't used so far
- change through all channel works
- Radio protocol is fully implemented - no well known bugs
- Start of watch can be triggered by: button on the StopWatch itself, via Starter or remote control When StopWatch start button is used, the Starter will be locked and not react on any other device than GT Connect or the StopWatch
- End of StopWatch: either pressing the start button or ball is running trough the Finish element. This releases the lock of the Starter.
If i have would have the need to order a new PCB, i would consider a few changes/improvements:
- add Crystal (more precision :) )
- Change LED resistor to: Error/Yellow(330), Green(330), Red(1,5k), Blue(1,5k)
- add pin description to i2c header
- add i2c debug pin header
- add possibility to mount dispaly
- add 2nd i2c header for 90° rotated 128x64 OLED Display
- add jumper to allow USB VCC disconnect
- add jumper to disconnect USB 3.3V
- more space between error LED and MCU reset button
- move XN297L board more out of the board (provide more space for antenna)