Unable to read from ADAU1701 via microcontroller (With Pictures)

Hello berk,

This is one of our older processors and we improved things a lot after this part. You cannot directly access the readback. You have to use the trap register. This is detailed in the datasheet and I detailed it further in this old post:

(+) ADAU1701 Low Instruction Level Detection Readback - Q&A - SigmaDSP Processors & SigmaStudio Dev. Tool - EngineerZone

For my quick little test program I have a DC cell feeding a readback and it is listed in the trap register text file:

It is the first thing on the list since it was on the top left of the schematic.

In my case I would have to write a decimal 31 into the trap register. Note in your program it is writing an 0x22 into the trap register address of 0x081A and then going back to read the result at least one sample period later.  

Dave T

Thank you for your answer Dave. My program outputted: Instance 2 Signal ReadBack1_ReadBackAlg1 trap value 8 register MAC_out

According to the output and table 27 and 28, I should be able to read from the ADAU1701 DSP as,

void SIGMA_READ_REGISTER_BYTES(int address = 0x81A) {

ADI_REG_TYPE write_buffer[4];

write_buffer[0] = (address & 0xFF00) >> 8; // Byte 0: Address high byte

write_buffer[1] = (address & 0x00FF); // Byte 1: Address low byte

write_buffer[2] = (0x22 & 0xFF00) >> 8;

write_buffer[3] = (0x22 & 0x00FF);

ADI_REG_TYPE read_buffer[5];

read_buffer[0] = (address & 0xFF00) >> 8;

read_buffer[1] = (address & 0x00FF);

HAL_StatusTypeDef transmitStatus, receiveStatus;

transmitStatus = HAL_I2C_Master_Transmit(&hi2c2, 0x68, write_buffer, 4, HAL_MAX_DELAY);

Hal_Delay(100);

receiveStatus = HAL_I2C_Master_Receive(&hi2c2, 0x69, read_buffer, 5, HAL_MAX_DELAY);

if (receiveStatus == HAL_OK) {

HAL_GPIO_WritePin(LED_2_GPIO_Port, LED_2_Pin, GPIO_PIN_SET);

} else {

Error_Handler();

}

}

but still I cannot read it. Do you see any missing points on my implementation?

I finally figured out the problem. The main problem relies with "Repeated start requirement". In order to fix this I changed 

HAL_I2C_Master_Transmit(..) to HAL_I2C_Mem_Read(..)

and the problem is somehow solved.

Yes, the repeated start is important in certain places so you maintain the memory address but change the command from a write to a read. You have to write to set the data address you want to read from. Then perform a repeated start to change it to a read to read from that address you set in the last write command...

Glad you got it going!

Dave T

My bad! I put the wrong line to my solution reply. In the end  HAL_I2C_Mem_Read(..) was the lifesafer eventough I dont know why :) Thank you for your time Dave! Your explanations were really helpful!