I am attempting to communicate with the arduino through I2C. The arduino is set up a slave and a raspberry pi as master. I want to write a value to the arduino, depending on this value the arduino writes a string back. I will always write a value before requesting data. I can't seem to get this to work. My code is as below:
#include <Wire.h>
int measurement = 0;
bool readComplete = false;
void setup() {
Serial.begin(9600);
Wire.begin(0x9);
Wire.onReceive(receiveFunction);
Wire.onRequest(requestFunction);
}
void receiveFunction(int howmany){
if(readComplete == false){
measurement = Wire.read();
readComplete = true;
Serial.print("read complete: ");
Serial.print(readComplete);
}
}
void requestFunction(){
if(readComplete){
Serial.print("\nRequested: ");
Serial.print(measurement);
Serial.print("\n");
switch (measurement) {
case 1:
Serial.print("Sensor 1");
Wire.write("1.11");
break;
case 2:
Serial.print("Sensor 2");
Wire.write("2.22");
break;
default:
Serial.print("Default\n");
Wire.write("3.33");
break;
}
readComplete = false;
Serial.print("Read Complete: ");
Serial.print(readComplete);
Serial.print("\n");
}
}
void loop() {}
For some reason whenever I request data from the I2C, that is I attempt to read the value from the value, the arduino registers a write before sending the data. For example master writes 2 to the arduino -> master reads data -> This read rereads measurement to 0 (not sure why) -> Switch defaults and writes 3.33. I can repeat this with different numbers without reseting the arduino but I always get the default.
In an attempt to get around this I introduced the global variable as above. This works as a flag to ensure measurement is only set AFTER a master read. Then I request data in the order master write -> master read -> master write -> master read etc. The boolean is correctly set and reset as evident by monitoring the serial, however, I can't request any data. The arduino acknowledges its address but simply writes [1, 255, 255, 255], I assume because it is no longer pulling the I2C low. I have to reset the arduino, after which it works once, fulfilling one master write -> master read cycle before the arduino needs to be reset again.
Any help anyone could give would be greatly appreciated!
