bq27510 data flash writing

Hi,

I'm trying to configure the bq27510 Gas Gauge without using the user interface, since I don't expose the SDA/SCL pins.

I've read the datasheet and various threads on this forum, but I still have problems with the write process.

As an example, I try to change the Op Config register from 0x0979 to 0x0978. My I2C routines use as parameters: the component 7-bit address, an address/data buffer, the number of bytes to write/read

// Write BlockDataControl

off[0] = 0x61;  off[1] = 0x00;

I2CWrite(0x55, off, 2);  WaitDelay();

// Write DataFlashClass

off[0] = 0x3E;  off[1] = 0x40;

I2CWrite(0x55, off, 2);  WaitDelay();

// Write DataFlashBlock

off[0] = 0x3F;  off[1] = 0x00;

I2CWrite(0x55, off, 2);  WaitDelay();

// Calculate checksum

off[0] = 0x60;

I2CWrite(0x55, off, 1);

I2CRead(0x55, &checksum, 1);

checksum -= 0xFF;

checksum = 0x79 - checksum;  // convert old value...

checksum += 0x78;  // ...with new value

checksum = 0xFF - checksum;

// Write new data

off[0] = 0x41;  off[1] = 0x78;

I2CWrite(0x55, off, 2);  WaitDelay();

// Write checksum

off[0] = 0x60;  off[1] = checksum;

I2CWrite(0x55, off, 2);  WaitDelay();

That's all.

....and it doesn't work! The value will never be updated.

Am I missing something?

Also, reading the control status like this

// Calculate checksum

off[0] = 0x00;  off[1] = 0x00;  off[2] = 0x00;

I2CWrite(0x55, off, 3);

I2CRead(0x55, status, 2);

I get a status 0x0400 or 0x0004 (I don't remember the correct one. By the way, both values state that the device is not in sealed mode)