BQ79656EVM-021: Related to FAULT monitoring

Abhaya Raj Mishra

Intellectual 305 points

Part Number: BQ79656EVM-021

Hi,

I'm using 4 Bq79656 EVM. for cell voltage monitoring. (without master (BQ79600))

Please guide me to how I can implement the fault monitoring in this, mainly which register need to be monitor?

And if I will be using the BQ79600 as master then which fault register need to be monitor?

Thanks, and Regards

Abhaya Raj Mishra

over 1 year ago

0 Quentin Silic over 1 year ago

TI__Expert 7000 points

Hello Abhaya,

You can monitor the NFAULT pin. It will be pulled low when a fault occurs and this can be used to notify an MCU. If a fault occurs on an upper stack, all stacks below will also trigger NFAULT and pull it low. If you want specifics on what fault was triggered, read the FAULT_SUMMARY register.

Best,

Quentin

0 Abhaya Raj Mishra over 1 year ago in reply to Quentin Silic

Intellectual 305 points

Ok, Thank you so much.

I'll try to implement the same.

Thanks & Regards

Abhaya Raj Mishra

0 Abhaya Raj Mishra over 1 year ago in reply to Quentin Silic

Intellectual 305 points

I have implemented the same.

Can you please suggest some test cases which can be performed to verify it?

0 Abhaya Raj Mishra over 1 year ago in reply to Abhaya Raj Mishra

Intellectual 305 points

Like how we can manually do some faults which can be seen in FAULT_SUMMARY register.

0 Quentin Silic over 1 year ago in reply to Abhaya Raj Mishra

TI__Expert 7000 points

Hello Abhaya,

I like to run the OVUV protector and set an OV threshold. For example. If my cells are at 3V I will put an OV threshold of 3.3V.

Then I will increase the voltage supply of the device and watch all the OV faults trigger.

Best,

Quentin

0 Abhaya Raj Mishra over 1 year ago in reply to Quentin Silic

Intellectual 305 points

I tried with under voltage one, I reduced the overall voltage of slack device to 10V (VSTACK), the NFAULT pin voltage dropped to 0 V but there was no update in FAULT_SUMMRY register value.

Please help me in the same.

0 Quentin Silic over 1 year ago in reply to Abhaya Raj Mishra

TI__Expert 7000 points

Hello Abhaya,

Can you send me pseudo code of how you are enabling the OVUV protector and threshold? Also make sure the device is still on when you drop it down to 10V.

Best,

Quentin

0 Abhaya Raj Mishra over 1 year ago in reply to Quentin Silic

Intellectual 305 points

WriteReg(0, OVUV_CTRL, 0x04, 1, FRMWRT_STK_W);  //    Setting OVUV_GO value to 1 for starting the OV UV comparator
WriteReg(0, OV_THRESH, 0x23, 1, FRMWRT_STK_W);  //    over-voltage Threshold (4.2V)
WriteReg(0, UV_THRESH, 0x20, 1, FRMWRT_STK_W);  //    under-voltage Threshold (2.8V)

Devices are still on but, in console I'm getting all 0V for all cells for all boards(4 boards).

0 Quentin Silic over 1 year ago in reply to Abhaya Raj Mishra

TI__Expert 7000 points

Hello Abhaya,

All your settings are sampled when you send a 'GO' command. Writing OVUV_GO should be the last thing you do after you make all your communications.

Also OVUV is the over-voltage under-voltage comparator. If you are trying to read the cell voltages you need to look into the datasheet and look into running your main ADCs.

Best,

Quentin

0 Abhaya Raj Mishra over 1 year ago in reply to Quentin Silic

Intellectual 305 points

Ok I'll try with this method once.

Thank you.

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BQ79656EVM-021: Related to FAULT monitoring