I2C Master send reset command to the slave counter

Question

My name is Gianni, I live in Olbia Sardinia Italy and I have some experience in electronics.

For several years I have been passionate about Arduino.

They are now engaged in a project to counter with hall sensors.

The slave sends data to the master via I2C, for my project. I'm using the sketch of Gammon which uses a structure enum to send a request to the slave.

I have the need to send a reset command from master to slave.

I edited the sketch and I can see the command on the slave but will not let me use it to reset the counter.

---

Master code section

 void RstCounter() 
 {
 Serial.println ("funzione azzera attivata"); 
 Serial.println (sensor);
 char key = keypad.getKey(); 
 if (key !='A') 
 {
 char cmdrst = 'a';
 //set=key; 
 if (sensor==11)
 {
 sendCommand (CMD_WRITE_D2, 1);
 Wire.beginTransmission(SLAVE_ADDRESS); // testiamo questa istruzione
 Wire.write(cmdrst); 
 Wire.endTransmission();
 delay(100);
 Serial.println (cmdrst); 
 }
 else 
 {
 m=0;
 }
 azzera =true; 
 }
 else if (key=='A') 
 { 
 Serial.println("");
 Serial.println("AZZERA close");
 azzera = false;
 }
 delay(100);
 }

---

SLAVE code section

#include <Wire.h>
const byte MY_ADDRESS = 42; // address in valore esadecimale
/************ VARIABILI SENSORI **********************/
#define Sensor11 2 
int lastValueSensor11 =0;
int ValueSensor11=0;
int contatore11=0;
int counter11;
// various commands we might get
/************ VARIABILI ENUMERATORE **********************/
enum {
 CMD_ID = 1,
 CMD_READ_D2 = 2,
 CMD_READ_D3 = 3,
 CMD_READ_D4 = 4,
 CMD_WRITE_D2 = 5
 };
char command;
int sensor;
char cmdrst;
/************ SETUP **********************/
void setup() 
 {
 command = 0;
 pinMode (Sensor11, INPUT);
 digitalWrite (Sensor11, HIGH); // enable pull-up
 Serial.begin(9600);
 Wire.begin (MY_ADDRESS);
 Wire.onReceive (receiveEvent); // interrupt handler for incoming messages
 Wire.onRequest (requestEvent); // interrupt handler for when data is wanted
 } // end of setup
/************ LOOP **********************/
void loop() 
 {
 /************************ CONTATORE SENSOR 1 ***********************/
 ValueSensor11 = digitalRead(Sensor11); 
 if ( ValueSensor11 != lastValueSensor11) 
 { if ( ValueSensor11 == LOW)
 { 
 contatore11 = contatore11 + 1; 
 }
 }
 lastValueSensor11 = ValueSensor11;
/************ I2C RECEIVE **********************/
void receiveEvent (int howMany)
 {
 command = Wire.read (); // remember command for when we get request
 //Serial.println(command);
 switch (command)
 {
 case CMD_WRITE_D2: 
 Serial.println("comando 5 ricevuto"); 
 char cmdrst=Wire.read();
 delay(100); 
 Serial.println (cmdrst);
 break;
 }
} // end of receiveEvent
void sendSensor1 (const byte which)
 {
 int val11 = contatore11;
 Serial.println(contatore11);
 byte buf11 [2];
 buf11 [0] = val11 >> 8;
 buf11 [1] = val11 & 0xFF;
 Wire.write (buf11, 2);
 } // end of sendSensor
void requestEvent ()
 {
 switch (command)
 {
 case CMD_ID: 
 Wire.write (0x55); 
 break; // send our ID 
 case CMD_READ_D2: 
 sendSensor1 (2); 
 break; // send A0 value
 case CMD_READ_D3: 
 sendSensor2 (3); 
 break; // send D8 value
 case CMD_READ_D4: 
 sendSensor3 (4); 
 break;
 } // end of switch
 } // end of requestEvent

Answer 1

void receiveEvent (int howMany)
 {
 command = Wire.read (); // remember command for when we get request
 //Serial.println(command);
 switch (command)
 {
 case CMD_WRITE_D2: 
 Serial.println("comando 5 ricevuto"); 
 char cmdrst=Wire.read();
 delay(100); 
 Serial.println (cmdrst);
 break;
 }
} // end of receiveEvent

• Don't do serial prints inside an interrupt service routine (ISR). That is, not here.

• Don't do delay inside an ISR.

---

 if (key !='A') 
 {

I would be checking for NO_KEY first, otherwise you will assume that no key press is not 'A' and be doing that transmission to the slave a lot.

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