Problem with daisy chaining BQ76PL536A-Q1 devices

Murat Ilhan

Other Parts Discussed in Thread: BQ76PL536A-Q1

Dear Experts,

One of our customers is designing with our BQ76PL536A-Q1 device. They have completed their first prototype using 6 series cells and were able to communicate with the MCU Demo board successfully and were able to balance them. Next, they tried to connect a second BQ76PL536A-Q1 device (on its own Card) serially (daisy chain) and tried to work it with 12 series cells but failed to do so. They were not able to address this second BQ device or communicate with it (No read or write). Attached you can see the schematic and information on Message Packets sent and received. I can also send you the scope shots if needed.

We are thinking that this problem may have to do with voltage values of negative 500~1000mV but not sure at all.

Note1: We are first trying to address the devices and then read the addresses back in order in our message packets. We are able to receive the address of the first device as x81 correctly but getting x00 from the second device and not able to read it.

Note2: When we were implementing this daisy chain structure, we took care of the datasheet documents and the ref design. (In the additional card, KN3 and KN4 connectors' first 8 pins and the 15th&16th pins are tied together with 7cm jumper wires).

I'd appreciate if anyone can give their professional opinion on what may be going wrong here.

Thanks,

Murat Ilhan.

TI-Turkey.

over 8 years ago

0 Roger Hwang over 8 years ago

TI__Genius 10785 points

bq76Pl536 addressing.pdfMAke sure Hsel is pull up to LDOD. I think you have on LDOA but LDOD is prefer but shuold be okay for addressing device.

see the attachment.

I think you can easily follw the attached document.

Let me know if you have follow up questions.

0 Murat Ilhan over 8 years ago in reply to Roger Hwang

TI__Expert 4840 points

Thanks Roger, will do.

Best regards,

Murat.

0 Xavier Anzuela Recasens over 8 years ago in reply to Murat Ilhan

Prodigy 40 points

Did that algorithm solve your problem? I have the same problem.
Does there have to be a specific time between comands to the SPI?

0 Roger Hwang over 8 years ago in reply to Xavier Anzuela Recasens

TI__Genius 10785 points

I think so.

There is no specific timing required in this case.

Please try my suggestion and let us know if you still have a problem.

0 Xavier Anzuela Recasens over 8 years ago in reply to Roger Hwang

Prodigy 40 points

This is the code I am using now adapted from a TI document:

int address_discovery(void)
{
unsigned short i, n;

i=Total_IC; //controls iteration loop
while (i>0)
{
//*Send BROADCAST_RESET to address 0x00*/
Write_IC(Broadcast,RESET_Reg,Reset_Addr);

n=0; //controls number of discovered devices
while (n<Total_IC)
{
//*Read DEVICE_STATUS reg at address 0x00*/
Discover(); // Sends SPI message 00 00 01 00 00
if (data[3]==0x00) //data[3] safes the variable returned by SPI in position 00[0] 00[1] 00[2] 61[3] 35[4]
{
n = Total_IC; //break internal loop
}
else
{
Write_IC(0x00,ADDR_Control,1); Sets
n++;
//read ADDR_CTRL
CHECK_ADDR(IC_count);
if (data[3] == (0x80| n))
{
//address next device or finish device detection
if (n==Total_IC)
Enable_Discovery=0;
return n;
}
else
{
//break internal loop
n = Total_IC;
}
}
}
i--;
}
return 0;
}

This code only addreses the first chip. Total IC is set to 2 in this case.

Thanks

0 Roger Hwang over 8 years ago in reply to Xavier Anzuela Recasens

TI__Genius 10785 points

Xavier,

Go check this application code.

I think you can get actual MSP430 code for your reference.

0 Xavier Anzuela Recasens over 8 years ago in reply to Roger Hwang

Prodigy 40 points

Problem solved, my clock was HIGH insteard of LOW and my PIC was doing some strange things. I switched to an STM32 and now works perfectly fine with my software. I amb testint everything with the EV board.

0 Roger Hwang over 8 years ago in reply to Xavier Anzuela Recasens

TI__Genius 10785 points

thanks for your updates!!!!!

0 Murat Ilhan over 8 years ago in reply to Roger Hwang

TI__Expert 4840 points

Hi Roger,

My customer also solved their problem based on your recommendation.

Thanks again,

Murat.

0 Roger Hwang over 8 years ago in reply to Murat Ilhan

TI__Genius 10785 points

Hi Murat,

thanks for the update.

Roger

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Problem with daisy chaining BQ76PL536A-Q1 devices