BQ79656-Q1: BQ79656

Hi Vamshi,

Could you send a capture of your SPI commands? Are you following the auto address sequence in the datasheet? 

Thanks,

Chase

Hi Chase,

I have access to SPI sample code provided by TI mysecure SW. So, I am following the sequence as per that only. Below is the code for your reference and verification. 

FYI I am only using single slave device for the sensing of 16 cell voltages, there is no any other stack device present in system.

//AUTO ADDRESS SEQUENCE
//**********************
void SpiAutoAddress()
{
//DUMMY WRITE TO SNCHRONIZE ALL DAISY CHAIN DEVICES DLL (IF A DEVICE RESET OCCURED PRIOR TO THIS)
SpiWriteReg(0, OTP_ECC_DATAIN1, 0X00, 1, FRMWRT_STK_W);
SpiWriteReg(0, OTP_ECC_DATAIN2, 0X00, 1, FRMWRT_STK_W);
SpiWriteReg(0, OTP_ECC_DATAIN3, 0X00, 1, FRMWRT_STK_W);
SpiWriteReg(0, OTP_ECC_DATAIN4, 0X00, 1, FRMWRT_STK_W);
SpiWriteReg(0, OTP_ECC_DATAIN5, 0X00, 1, FRMWRT_STK_W);
SpiWriteReg(0, OTP_ECC_DATAIN6, 0X00, 1, FRMWRT_STK_W);
SpiWriteReg(0, OTP_ECC_DATAIN7, 0X00, 1, FRMWRT_STK_W);
SpiWriteReg(0, OTP_ECC_DATAIN8, 0X00, 1, FRMWRT_STK_W);

//ENABLE AUTO ADDRESSING MODE
SpiWriteReg(0, CONTROL1, 0X01, 1, FRMWRT_ALL_W);

//SET ADDRESSES FOR EVERY BOARD
for(currentBoard=0; currentBoard<TOTALBOARDS; currentBoard++)
{
SpiWriteReg(0, DIR0_ADDR, currentBoard, 1, FRMWRT_ALL_W);
}

//BROADCAST WRITE TO SET ALL DEVICES AS STACK DEVICE
SpiWriteReg(0, COMM_CTRL, 0x02, 1, FRMWRT_ALL_W);

//SET THE HIGHEST DEVICE IN THE STACK AS BOTH STACK AND TOP OF STACK
SpiWriteReg(TOTALBOARDS-1, COMM_CTRL, 0x03, 1, FRMWRT_SGL_W);

Thanks,

Vamshi

HI Vamshi,

When you see SPI_RDY go high do you drop the CS signal? After dropping the CS signal then you can send the write command. After the write command then pull CS high.

Then to read, wait for SPI_RDY to go high, drop the CS signal and send the read command and raise the CS. Then you should check SPI_READY to be high again then drop the CS, read your data, and then stop the CLK and and raise CS high. You can see the flow chart in the BQ79600 datasheet on page 20

Hi Chase Fagen

We are using MATLAB function to do the auto addressing sequence. 

Since it is a model-based approach, the CS signal is automatically pulled down before command is sent and pulled up after the command is sent. 

We have implemented a counter as shown in the figure - 

The counter is to move in a sequential fashion.

The below function is used to proceed for a single device Auto-addressing.

function y = fcn(SPI_RDY, T_C)
if(SPI_RDY==1)
switch T_C
case 1
y=[0x90 0x00 0x03 0x43 0x00 0x25 0x2D];
case 2
y=[0x90 0x00 0x03 0x09 0x01 0xD3 0x8D];
case 3
y=[0x90 0x00 0x03 0x06 0x00 0x17 0xBD];
case 4
y=[0x90 0x00 0x03 0x08 0x02 0x92 0x1C];
case 5
y=[0x90 0x00 0x03 0x08 0x01 0xD2 0x1D];
case 6
y=[0xC0 0x03 0x4C 0x00 0xF8 0xE4 0x00];
otherwise
y=[0x00 0x00 0x00 0x00 0x00 0x00 0x00];
end
else
y=[0x00 0x00 0x00 0x00 0x00 0x00 0x00];

end
end

We got this sequence from the datasheet and EVM user guide, but we are unable to get any response from the slave with the above sequence.

Do we have to monitor SPI_RDY pin during the entire auto-addressing sequence to send individual read/write commands at each consecutive SPI_RDY highs and lows in the above sequence? or is it enough for the SPI_RDY pin to go high one time followed by the 6 steps shown above?

Also, one other thing we observed is that as soon as we power-up the EVM board it is going to fault mode (indicated by red LED). We are able to wake-up the Slave IC even in this state, but should it go into fault state as soon as we turn it on??

Thanks,

Vamshi