BQ78PL116 Safety History

Patrick,

We do not have an Applications Report that covers the Safety History, but I am trying to get answers for you.

Regards

Tom

Patrick, 

The Event Value in the Safety History provides post reset status information. An 11 indicates normal operation after a power on reset and a 21 indicates normal operation after an external reset has occurred.

Regards

Tom

Thanks Tom,

Do you have a list of event codes?  I have another code, reset code 41.

Thanks,

Patrick

Patrick,

I tracked down the decoder ring for the Event History.

The most significant digit gives the source of the last reset.  The least significant digit gives the current operational state.  In this case (41) the code indicates normal operation after a watchdog reset.

 //Reset sources (Tens digit)
1 = power on reset
2 =external reset
3 =reset after download
4 =watchdog reset
5 =safety reset
6 =reset by stray (spurious) irq
7 =reset at detection of stack fault
8 =app gave up
F=unknown

//operational status
1=fully operational, normal
2 =in boot-loader because app is corrupted
3 =in bootloader because FDirectory is corrupted
4 =in bootloader because app is not compatible with system
5=in bootloader because f-file is different from app expects
6 =app asked to stay in,  Sys_Status.reset_para tells
                                     //for num stack fault exceeded allowance
                                     //for other reasons through APP_DROP

Regards

Tom

Thanks Tom,

This helps but brings up another question of why the precharge condition caused the watchdog reset.

Patrick

Patrick,

Were there any faults noted in the Safety History or in bqWizard? The Watchdog monitors communications with the host and can issue a reset if communications is interrupted for more than the Host Watchdog Timeout setting. The Watchdog monitor can be disabled by setting it to "0".

Regards

Tom

Tom,

Yes there are some faults in the Safety History:

I was testing the precharge behaviour when this occurred and the log file contents are concerning.  The cell under voltage threshold is 2900mV and cell under voltage recovery is 3100mV.  I was expecting to see <100mA charge current in this condition but the currents in the Safety History log appear to be normal charge current levels (~2000mA)  I have monitored the charge current previously during precharge conditions and it was below 100mA.  The CHG and PRECHG FETs appear to be responding properly and consistent with BQWizard.

Patrick 

Patrick, 

The current should be the pre-charge current set by you current limiting resistor when in pre-charge mode. Could you send me you .ppcsv and a log file that covers when the event occurs? I will try to help you diagnose the problem. A schematic may be helpful as well.

Thanks

Tom

Tom,

I cannot generate a .ppcsv file while the host controller is running due to contention on the SMBus.  Is there a way I could read the Safety log with the host microcontroller?

Patrick

Patrick,

I am not aware of a way to use the host controller and bqWizard on the SMBus at the same time. Communication on one of them will have to be halted to prevent conflicts.

Tom

Tom,

I was thinking about having the host controller reading the safety log if possible.

Patrick

It is possible to read the Safety History from the device, but the process is rather complicated and not support outside of bqWizard at this time.