Initial contact with I2C

Using Arduino Networking, Protocols, and Devices
24

I'm looking at Figure 5-11

I think I was confusing what they label as "receive byte" and "read byte". Rather ambiguous.

A0..2 have pull-ups as already noted. This is consistent with the scanner output.

The current , full sketch:

#include <Wire.h>

#define I2C_SLAVE_ADDR 0x1F  // 0x1F << 1 = 0x3E

void setup() {
	Serial.begin(115200);
  Serial.write("Arduino I2C v0\r\n");
  
  Wire.begin();  // init TWI lib
 	init_I2C();
}


void init_I2C() {
  	
	byte status=0;
  byte res=0;
    Wire.beginTransmission(I2C_SLAVE_ADDR);
    if ( Wire.endTransmission() !=0 ) {
      Serial.println("slave 0x1F not responding\r\n Halting.");
      while (1) ;
    }
    
    Serial.println("send request - get case status byte");
    
         Wire.beginTransmission(I2C_SLAVE_ADDR);
         Wire.write((byte)0xD8); // set status register address
         res=Wire.endTransmission(false);
         if (res != 0 ) { 
           Serial.print("endTransmission error ");
           Serial.println(res);
         }
         Wire.requestFrom(I2C_SLAVE_ADDR,1); //read case status byte
         if  ( Wire.available() == 0 ) {
            Serial.println("No data on bus\r\n");
         } else {
           status=Wire.read() ;
           Serial.print("status = "); Serial.println(status,HEX);
         }  



       // next cmd 
    Serial.println("send request 2 - get module status byte");

         Wire.beginTransmission(I2C_SLAVE_ADDR);
         Wire.write((byte)0x98); // set status register address
         res=Wire.endTransmission(false);
         if (res != 0 ) { 
           Serial.print("endTransmission error ");
           Serial.println(res);
         }
         Wire.requestFrom(I2C_SLAVE_ADDR,1); //read case status byte
         if  ( Wire.available() == 0 ) {
            Serial.println("No data on bus\r\n");
         } else {
           status=Wire.read() ;
           Serial.print("status = "); Serial.println(status,HEX);
         }  
           
} // end init_I2C()


void loop() {
	while (1) ;
}

The output from that is :

Arduino I2C v0
send request - get case status byte
endTransmission error 3
status = 0
send request 2 - get module status byte
status = 0

language ref says that return value means:

3:received NACK on transmit of data

Odd, since the iMP doc says:

Command Error [Ref#1, 4.1]
This protocol does not support NACKing the command code or data bytes as they are being received.