...
int i = slave.receive();
switch(i) {
    case I2CSlave::ReadAddressed:
        //SOMEHOW GET THE DATA ADDRESS
        //STORE IN SOME VARIABLE v
        switch(v) {
            case 0x00: //This is the whoami register, return device id
                buf[0] = 0x10;
                slave.write(buf,1);
                break;
            ...
        }
        break;
   ...
}
...

Hey Guys, Quick question regarding the I2C Slave library that was not immediately apparent. I understand that the receive method returns a status to check regarding if there is a read/write request from the master. I would like to set up my slave program to have multiple readable and writable registers like most slave devices. I have not, however, seen a way to get the data address that the master is trying to access. Ex. My device address is 0x10 and should implement the following table: |=Name |=Permissions |=Data Address |=Read Response |=Write Action | | Whoami | R | 0x00 | Device ID | N/A | | Control1 | RW | 0x01 | Actual Value | Set Setpoint | | Control2 | RW | 0x02 | Actual Value | Set Setpoint | | Sensor | R | 0x03 | Sensor Data | N/A | So, in this case, the program pattern should go something like: <<code>> ... int i = slave.receive(); switch(i) { case I2CSlave::ReadAddressed: //SOMEHOW GET THE DATA ADDRESS //STORE IN SOME VARIABLE v switch(v) { case 0x00: //This is the whoami register, return device id buf[0] = 0x10; slave.write(buf,1); break; ... } break; ... } ... <</code>> Can anyone point me in the right diection?

... 
int i = slave.receive(); 
int v = 0; // selected slave register;
switch(i) { 

case I2CSlave::WriteAddressed: 
  slave.read(buf, 2); // assume we only accept address and max of one databyte
  
  v = buf[0];  // buff[0] is the registeraddress
               // note: you need more code to handle the
               // one byte registerselection transfer for a follow on read.

  // test here to make sure we did receive a databyte before overwriting
  switch (v) {
     case 0:
             //This is the whoami register, ignore 
             v = 1; //autoincrement   
             break; 

     case 1:
             //This is the setpoint register 
             setpoint = buf[1];
             v = 2; //autoincrement   
             break; 

        ......
  }

  break;


case I2CSlave::ReadAddressed: 
   switch (v) {
     case 0:
             //This is the whoami register, return device id 
             buf[0] = 0x10;
             slave.write(buf,1); 
             v = 1; //autoincrement   
             break; 

     case 1:
             //This is the setpoint register 
             buf[0] = setpoint;
             slave.write(buf,1); 
             v = 2; //autoincrement   
             break; 

        ......
   } 
   Break;
 ... } 

The master needs to write a single byte indicating the registeraddress. Any following byte will be written to the selected register. The slave will autoincrement the registeraddress when the master sends more than one byte of data. Reading from the registers is done by first writing the selected registeraddress. The master then ends the I2C write transmission and restarts reading the slave. The slave then sends the data from the selected register and again autoincrements when the master wants more data. Below is some example code which is not complete yet. <<code>> ... int i = slave.receive(); int v = 0; // selected slave register; switch(i) { case I2CSlave::WriteAddressed: slave.read(buf, 2); // assume we only accept address and max of one databyte v = buf[0]; // buff[0] is the registeraddress // note: you need more code to handle the // one byte registerselection transfer for a follow on read. // test here to make sure we did receive a databyte before overwriting switch (v) { case 0: //This is the whoami register, ignore v = 1; //autoincrement break; case 1: //This is the setpoint register setpoint = buf[1]; v = 2; //autoincrement break; ...... } break; case I2CSlave::ReadAddressed: switch (v) { case 0: //This is the whoami register, return device id buf[0] = 0x10; slave.write(buf,1); v = 1; //autoincrement break; case 1: //This is the setpoint register buf[0] = setpoint; slave.write(buf,1); v = 2; //autoincrement break; ...... } Break; ... } <</code>> ...

Ah, thanks...I was working on it pretty late at night and the fact that the master writes the register it wants to read first completely escaped me. I got it going now. Thanks again