通过I2C与ROHM BU94603对话

Question

I am trying to write a simple program to communicate with ROHM BU94603KV Audio Decoder IC. The host controller I use is Atmega8. The language is C.

BU94603KV is AAC+WMA + MP3 decoder IC which contains USB host, SD card I/F, audio DAC, system controller, and regulator for internal CORE power supply.

I setup the hardware for MANUAL SLAVE MODE which can send the memory device information to the master microcomputer via the I2C interface and completely control sequences such as a play sequence by the master microcomputer (referred to as MODE3).

I'm trying to write a shortest test code for sanity checking. To do that, I write 0x5E and 0x03 to BU94603KV via I2C (Comand to read EQINF register). Everything seem to work correctly (no error return code form the I2C routine). However, the result is not what expected.

Here is my source code;

unsigned char BU94603_Read_Test(void){

unsigned char errorStatus;

errorStatus = i2c_start();
if(errorStatus == 1)
{
    i2c_stop();
    return(-1);
}

// STEP1 send command to read EQ ----------------------
while((PINC & (1<<BU94603_BUSY)));  // wait while BU94603 is busy
errorStatus = i2c_sendAddress(BU94603_WRITE_ADDRESS);
if(errorStatus == 1)
{
    i2c_stop();
    return(-2);
}

while((PINC & (1<<BU94603_BUSY)));  // wait while BU94603 is busy
errorStatus = i2c_sendData(BU94603_READ_STAT);
if(errorStatus == 1)
{
    i2c_stop();
    return(-3);
}

while((PINC & (1<<BU94603_BUSY)));  // wait while BU94603 is busy
errorStatus = i2c_sendData(BU94603_READ_EQ);
if(errorStatus == 1)
{
    i2c_stop();
    return(-4);
}
i2c_stop();

// STEP2 read EQ status --------------------------
errorStatus = i2c_start();
if(errorStatus == 1)
{
    i2c_stop();
    return(-5);
}

while((PINC & (1<<BU94603_BUSY)));  // wait while BU94603 is busy
errorStatus = i2c_sendAddress(BU94603_READ_ADDRESS);
if(errorStatus == 1)
{
    i2c_stop();
    return(-6);
}

while((PINC & (1<<BU94603_BUSY)));  // wait while BU94603 is busy
errorStatus = i2c_receiveData_ACK();
if(errorStatus == ERROR_CODE)
{
    i2c_stop();
    return(-7);
}

while((PINC & (1<<BU94603_BUSY)));  // wait while BU94603 is busy
errorStatus = i2c_receiveData_NACK();
if(errorStatus == ERROR_CODE)
{
    i2c_stop();
    return(-7);
}   

while((PINC & (1<<BU94603_BUSY)));  // wait while BU94603 is busy
errorStatus = i2c_receiveData_NACK();
if(errorStatus == ERROR_CODE)
{
    i2c_stop();
    return(-7);
}   

i2c_stop();
return(errorStatus);

}

The running result is 0xFB (supposed to be 0x40). What could be the problem?

Answer 1

Having return status and returned data in the same value is maybe a bit weird, especially when they can overlap.

Anyway, 0xfb is -5, so it looks like you have an issue with second i2c_start() failing. It might be that a loop waiting for BU94603 to be ready again is needed.

You didn't describe any pin configuration (usually you need to set pins to i2c mode), and also nothing on hardware side (common issue for a beginner would be missing pull-ups).

Do you have access to any hardware debugging tools (oscilloscope maybe)?