BQ27742EVM: BQ27742-G1

Hello Kavya,

Can you share your command sequence for updating the design capacity?

If you have a logic analyzer or scope I would recommend updating the value with the EV2400 (which is needed anyway to update the chemistry ID) and checking the communication sequence.

Sincerely,

Wyatt Keller

Hello Keller,

Thanks for replying. The command sequence I'm sending for updating design capacity is,

// Unseal gauge
unseal(); // writing default 0x36720414 key in key0 and key1 for unsealing.

// Enable Block Data Memory Control
blockDataControl(); //write 0x00 to 0x61 command
DelayMS(5); //5ms delay
// Access State subclass
blockDataClass(48); // issue 0x3e command to set data class 48 to be accessed.
// Write the block offset
blockDataOffset(0 / 32); // issue 0x3f command to set data block to access. 
// Read block checksum
computeBlockChecksum(); // Read all 32 bytes of the loaded extended data and compute a checksum based on the values.
uint8_t oldCsum = blockDataChecksum(); // Read the current checksum using 0x60 command.
uint8_t block[32];
//Update Design Voltage
block[0] = (uint8_t)( designVoltage >> 8 );
block[1] = (uint8_t)( designVoltage & 0x00FF );
// Update design capacity
block[10] = (uint8_t)( designCapacity_mAh >> 8 );
block[11] = (uint8_t)( designCapacity_mAh & 0x00FF );
// Write data bytes:
for (i = 0; i < 32; i++)
{
// Write to offset, mod 32 if offset is greater than 32
// The blockDataOffset above sets the 32-bit block
writeBlockData((0 % 32)+i , block[i]);
}

// Write new checksum using BlockDataChecksum (0x60)
uint8_t newCsum = computeBlockChecksum(); // Compute the new checksum
writeBlockChecksum(newCsum);
DelayMS(3000);
control_write( BQ27742_GAUGE_RESET ); write 0x0041 command to reset the gauge.
DelayMS(500);
seal(); //write 0x0020 to seal the gauge.

And I have few doubts like,

1. whether EV2400 is definitely required for flash update or can be done using command sequence. 

2. Why Chem ID is needed when read commands are working fine.

Hello Wyatt,

I don't have EV2400 with me. I'm trying to dump with microcontroller only. Does I need EV2400 definitely for this debugging. I'm not doing anything with chem ID currently, but when I measure voltage the reading is accurate only. Does that mean, no need of changing chem ID.

Thanks in advance,

Kavya.