BQ76940: is CRC necessary?

Pranit Pawar

Part Number: BQ76940

Hi,

I have bought BQ7694003 3.3v, CRC enables version. Is it necessary to use CRC while talking to IC via I2C ? In my current implementation, majority of BQ registers are read incorrectly. Also, I'm unable to change the value stored some registers. So in short, RW operation doesn't work as expected on most of the BQ registers. Is this because I'm not using CRC in the code?

over 6 years ago

0 Matt Sunna over 6 years ago

TI__Guru* 81034 points

Hi Pranit,

CRC is necessary if you are using the CRC version of the device.

Best regards,
Matt

0 Pranit Pawar over 6 years ago in reply to Matt Sunna

Intellectual 520 points

Thanks Matt!

I have not worked with CRC, so any resources or short codes on how to incorporate CRC in normal data frame?

0 Pranit Pawar over 6 years ago in reply to Pranit Pawar

Intellectual 520 points

1. My registerWrite(..) function takes in two parameters - register address and data. So when using CRC, do I have to append CRC byte to the end of the data byte and send the resulting 16bit combined value as data?

2. Register address will be 8 bit right? 7bit address (0x08) with RW bit?

3. What is the difference between read operation and write operation when using crc?

0 Matt Sunna over 6 years ago in reply to Pranit Pawar

TI__Guru* 81034 points

Pranit,

Are you able to get devices without CRC (the equivalent part is available without the CRC option)? If not, the CRC is required to write any register with I2C. The format is described in the datasheet.

There are also a couple of links that might be helpful.
www.ti.com/.../slva626 - This is microcontroller sample code for communicating with this device using CRC.
www.digikey.com/.../CRC Basics - This is a web site from Digikey describing CRC basics.

There are also many CRC calculators online that may help.

Best regards,
Matt

0 Pranit Pawar over 6 years ago in reply to Matt Sunna

Intellectual 520 points

Thanks again Matt! I found a sample code based on MSP + BQ76940. www.ti.com/.../sluc583.zip
I'll study the CRC functions and write my own codes for atmega328p.

Thank you so much!

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BQ76940: is CRC necessary?