Hey everyone, I've got an odd problem with I²C and the Wire Library.
Short description of my project:
I have an Arduino Due, which is responsible for most of the operations (TFT, temperature sensor ...) and an extra GSM Module on an Arduino Uno. I connected these two with I²C. At first, the Due needs to check, if the GSM Module is already connected to a net. So it sends a special "Op-Code" (In my case: "A") to tell the Uno, the next request it has to send back the gsm status. Every 5 seconds it will be checked.
That works fine: When the Uno is not connected, the Due prints a (GSM Module not connected. "0"), when I turn the Uno on, it prints (GSM Module not connected to net yet. "1") and when it's connected, it says connected ("2"). But when I plug it off again, it still says, it's connected, Wire.read() returns a "2". That cant be since there's no other slave on the bus. What's happening here?
Even when the GSM module loses the connection and goes to state 1, the Due gets state 2...
the fact that Wire.available() returns a non-zero value irritates me, since he CANT get an answer.
I don't know whats wrong here:
I cut out irrelevant parts.
Master (Due):
loop() {
if (gsmcounter - gsmcounterold > 5000) {
gsmcounterold = gsmcounter;
w_Writer('A');
Wire.requestFrom(4, 1);
}
if (Wire.available()>=1) {
gsmConnected = Wire.read();
Serial.println(gsmConnected);
if (gsmConnected == 1) {
Serial.println("GSM-Modul noch nicht mit Netz verbunden!"); //GSM module not connected to net
} else if (gsmConnected == 2) {
Serial.println("GSM-Modul verbunden!"); //GSM module connected
} else {
Serial.println("GSM-Modul nicht erreichbar!"); //GSM module not reachable
}
}
}
void w_Writer(char c) {
Wire.beginTransmission(4);
Wire.write(c);
Wire.endTransmission();
delay(5);
}
Slave (Uno):
void receiveEvent(int m) {
switch (state) {
case 0:
c = Wire.read();
.
.
.
}
void requestEvent() {
switch (c) {
case 'A':
if (notConnected) {
Wire.write(1);
Serial.println("1");
} else {
Wire.write(2);
Serial.println("2");
}
break;
}
}
