Quote:
Originally Posted by Richard100
Thanks. In 'Begin', you use a value of '4' as the Device Address for the I2C Open VI, and a value of '6' as the I2C Register for the I2C Write used in your I2C Comms VI ... can you explain those values?
Do you have a wiring diagram for the Arduino I2C connection?
|
The 6 is arbitrary, it's sent as the first byte of the packet and the Arduino code just discards that byte.
The 4 is the I2C slave address for the Arduino. In the Arduino side the address is actually set to 2, there's some sort of difference in the addressing scheme between the two devices which means that the cRIO needs to use an address that is the Arduino address shifted one bit to the left. It's something to do with 7 vs 8 bit I2C addressing but I don't know exactly how it works.
As for wiring it, we just used a male-female PWM cable between the I2C port SCL, SDA, and ground pins on the sidecar running to the SCL, SDA, and (unused) pin 19 of an arduino mega 2560 clone.