BQ79616-Q1: not being able to set up daisy chain communication

Hi,

Have you performed auto addressing? Please get the details on datasheet, and download TI sample code for 616. If you believe your code is correct, can you draw a simple block diagram? I am not pretty sure of your configuration. 

So, we have 2 IC, BQ79656 and BQ79616, we have connected BQ79656 to ISO and than to MCU UART.

Here is the block diagram,

Following is code snippets,

// daisy chain sync start
BroadcastWrite(OTP_ECC_DATAIN1, 0);
WaitTx();
BroadcastWrite(OTP_ECC_DATAIN2, 0);
WaitTx();
BroadcastWrite(OTP_ECC_DATAIN3, 0);
WaitTx();
BroadcastWrite(OTP_ECC_DATAIN4, 0);
WaitTx();
BroadcastWrite(OTP_ECC_DATAIN5, 0);
WaitTx();
BroadcastWrite(OTP_ECC_DATAIN6, 0);
WaitTx();
BroadcastWrite(OTP_ECC_DATAIN7, 0);
WaitTx();
BroadcastWrite(OTP_ECC_DATAIN8, 0);
WaitTx();
// auto addressing

BroadcastWrite(CONTROL1, 0x1);
WaitTx();
for(i=0;i<BQ_COUNT;i++)
BroadcastWrite(DIR0_ADDR, i);
WaitTx();
BroadcastWrite(COMM_CTRL, 0x2);
WaitTx();
SingleWrite(0, COMM_CTRL, 0x0);
WaitTx();
SingleWrite(1, COMM_CTRL, 0x3);
WaitTx();
// daisy chain sync stop
BroadcastRead(OTP_ECC_DATAIN1, 1);
WaitRx();   
// This is where code hangs as i dont receive anything on UART

Same code works with BQ_COUNT as 1 and with single one to one communication.

Wayne Liu said:

download TI sample code for 616

I have the sample code from TI along with that only we build our API, it works with single bq79616/656 but not on daisy chain, this is our concern right now.

This is the circuit we have used to achieve daisy chain between 2 ICs,

Also with respect to support from TI, is there a way to get support as per IST time zone ? the problem is i have to post a query and response will be during night time for us. this adds delay.

Have you connected RX to CVDD.for stack device?

You can get TI local sales team's support. Please just contact with them

Wayne Liu said:

Have you connected RX to CVDD.for stack device?

Yes

We have also added 1K terminating resistor to unused COMHx and COMLx pair

I don't see a complete auto addressing process on your code, can you please check on datasheet Table 9-19. Auto-Addressing?

// auto addressing

BroadcastWrite(CONTROL1, 0x1);
WaitTx();
for(i=0;i<BQ_COUNT;i++)
BroadcastWrite(DIR0_ADDR, i);
WaitTx();
BroadcastWrite(COMM_CTRL, 0x2);
WaitTx();
SingleWrite(0, COMM_CTRL, 0x0);
WaitTx();
SingleWrite(1, COMM_CTRL, 0x3);
WaitTx();

Are you telling me this is not auto addressing ? this i picked right from sample code

The read OTP_ECC_DATAIN1 for doesnt give any response so code wont move ahead i have read for OTP_ECC_DATAIN1 - OTP_ECC_DATAIN8 in sequence

same code works with Single device,  BQ_COUNT = 1

Not sure where you copied the sample code, i just copied it as below

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

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

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

WriteReg(0, COMM_CTRL, 0x02, 1, FRMWRT_ALL_W); //set everything as a stack device first

if(TOTALBOARDS==1) //if there's only 1 board, it's the base AND top of stack, so change it to those
{
WriteReg(0, COMM_CTRL, 0x01, 1, FRMWRT_SGL_W);
}
else //otherwise set the base and top of stack individually
{
WriteReg(0, COMM_CTRL, 0x00, 1, FRMWRT_SGL_W);
WriteReg(TOTALBOARDS-1, COMM_CTRL, 0x03, 1, FRMWRT_SGL_W);
}

//SYNCRHONIZE THE DLL WITH A THROW-AWAY READ
ReadReg(0, OTP_ECC_DATAIN1, response_frame2, 1, 0, FRMWRT_ALL_R);
ReadReg(0, OTP_ECC_DATAIN2, response_frame2, 1, 0, FRMWRT_ALL_R);
ReadReg(0, OTP_ECC_DATAIN3, response_frame2, 1, 0, FRMWRT_ALL_R);
ReadReg(0, OTP_ECC_DATAIN4, response_frame2, 1, 0, FRMWRT_ALL_R);
ReadReg(0, OTP_ECC_DATAIN5, response_frame2, 1, 0, FRMWRT_ALL_R);
ReadReg(0, OTP_ECC_DATAIN6, response_frame2, 1, 0, FRMWRT_ALL_R);
ReadReg(0, OTP_ECC_DATAIN7, response_frame2, 1, 0, FRMWRT_ALL_R);
ReadReg(0, OTP_ECC_DATAIN8, response_frame2, 1, 0, FRMWRT_ALL_R);

/*//OPTIONAL: read back all device addresses
for(currentBoard=0; currentBoard<TOTALBOARDS; currentBoard++)
{
ReadReg(currentBoard, DIR0_ADDR, response_frame2, 1, 0, FRMWRT_SGL_R);
printf("board %d\n",response_frame2[4]);
}*/

//RESET ANY COMM FAULT CONDITIONS FROM STARTUP
WriteReg(0, FAULT_RST2, 0x03, 1, FRMWRT_ALL_W);

return;
}
//**************************
//END AUTO ADDRESS SEQUENCE
//**************************

the code gets stuck at this step as there is no response from BQ IC, we checked the same on DSO, there is no activity on TX line of BQ

ReadReg(0, OTP_ECC_DATAIN1, response_frame2, 1, 0, FRMWRT_ALL_R);

Again same works with single BQ79xxx

I will invite our software expert to check it. 

HI Naik,

Are you sending the wake tone command 'SingleWrite(0, CONTROL1, 0x20)', to wake up the stack device i.e 616, are you seeing the LED 'ON' on BQ79616 ( device id 1). 

Can you try to do single device read from device id '0' and device id '1', check if you get response.

Can you capture the UART logs using  logic analyzer and also the scope shots of the COMH and COML lines between 656 and 616,  and share with us.

Can you please share the pic of your setup.

Thanks,

Ravi

Ravichandra Sereddy Thipperudra Reddy said:

Are you sending the wake tone command 'SingleWrite(0, CONTROL1, 0x20)', to wake up the stack device i.e 616, are you seeing the LED 'ON' on BQ79616 ( device id 1)

as per sample code Wake79616 should be used for waking up devices, We can see 5.0V on AVDD. When in shutdown, AVDD is 0V

we dont have LED on set up, its custom HW. We have 1 EVM board of 616.

Ravichandra Sereddy Thipperudra Reddy said:

SingleWrite(0, CONTROL1, 0x20)

This command will be accepted before Daisy chain sync and auto addressing ? cause we are getting stuck in Daisy chain read operation.

Ravichandra Sereddy Thipperudra Reddy said:

Can you try to do single device read from device id '0' and device id '1', check if you get response.

This again depends on daisy chain sync

The problem is not resolved, it kinda persisting. we dont have Logic analyzer.

I think that we have noticed the BQ Slave 1 and 2 wakeup on power properly on First wake TONE. But after that if we send shutdown tone theres is no effect on slave2 but slave1 is shutdown. After if we send wake tone slave1 wakes up again, however slave 2 is stays wake

Shutdown tone Width is 9ms verified on DSO

wakeup tone is 2ms verified with DSO

Shutdown tone doesn't propagate so the behavior is expected. Host has to talk to the neighboring device and sets the CONTROL1[SEND_SHUTDOWN] = 1
or CONTROL2[SEND_HW_RESET] = 1 to instruct the neighboring device to issue the corresponding tone, meaning to shutdown stack 2, you have to send a command to stack 1. then stack 1 send HWRESET tone to stack 2. 

I have gone through but i dont understand the behaviour i had to resend the WAKEUP twice to see any data from  both slave

Wake796xx();

    vTaskDelay(pdMS_TO_TICKS(11 * MAX_BQ796XX_COUNT));

Wake796xx();

    vTaskDelay(pdMS_TO_TICKS(11 * MAX_BQ796XX_COUNT));

Wake up tone routine

void Wake796xx(void) {

	// set GPIO as OUTPUT and pull low
	// delay should be 2.5ms
	SET_TX_IO_OUTPUT()
	;

	DEASSERT_TX_IO(); // Set TX as High
#if USE_RTOS_DELAY
	vTaskDelay( pdMS_TO_TICKS(10) )
#else
	OSIF_TimeDelay(10);
#endif

	ASSERT_TX_IO(); // Set TX as LOW
#if USE_RTOS_DELAY
	vTaskDelay( pdMS_TO_TICKS(3) )
#else
	delayMircoseconds(2700); // WAKE ping = 2.5ms
#endif

	DEASSERT_TX_IO();   // Set TX as High
	SET_TX_IO_UART()
	;
}

Hi Naik,

Apologies for the delayed response. 

So if you are sending 'Wake796xx(); once' both BQ79656 and BQ79616 are not waking up ?

The normal sequence is below, are you following this sequence.

1) Wake796xx(); // To wake up the BQ79656

2) delayus(100);

If COMH of BQ79656 is connected to COML of BQ79616

3) 'SingleWrite(0, CONTROL1, 0x20)' // Single write to BQ79656 to send wake tones to BQ79616

If COML of BQ79656 is connected to COMH of BQ79616

3) 'SingleWrite(0, CONTROL1, 0x80)' // Single write to BQ79656 to change the direction to reverse

4) delayus(100);

5) 'SingleWrite(0, CONTROL1, 0xA0)' // Single write to BQ79656 to send wake tones to BQ79616 in reverse directioni

With the above sequence you should see both the BQ79656 and BQ79616 should power up, then you should do auto addressing.

Can you probe the UART lines using oscilloscope and measure the wake ping, also can you probe the COMH line and see what you see when you send 'SingleWrite(0, CONTROL1, 0x20)

Thanks,

Ravi