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BQ27750: Programming I2C for BQ27750

Anonymous
Anonymous
Part Number: BQ27750
Other Parts Discussed in Thread: BQSTUDIO

Hello,

I want to use the bq27750 chip to read the state of charge of a 9V battery. For this I use the I2C interface of an Arduino.

I am not sure how to configure it correctly to get my information.
I start by sending the address 0x55 to start the communication.
However, I'm not quite getting through the communication protocol yet.
Which bytes do I have to send, if I want to know the current voltage value, for example.

I would build the protocol as follows:

0x55 (adress) - 0x08 - 0x09 and 16 bits for the answer. Is this correct?

Which general configurations do I have to make in order to be able to read out values such as charge state, temperature etc.?

Okay.
I need to calibrate the device first, correct?
How exactly is that done?
So what commands do I have to send to calibrate the device? The manual says that I should first test ManufacturerStatus()[CAL] = 0. How do I read the value?

Is an I2C protocol normally not structured in such a way that the address is sent, then the register to be addressed and then the data are transferred?

If I send it as described above, I get the following protocol:

I have measured the voltage at my battery and come to a value of 7.95V, thus 7950mV.
Accordingly, the chip should give me the following answer: 1111100001110 or 0x1F + 0x0E, possibly with a few deviations from the value... but not 144mV or 0x90.

Okay.
I need to calibrate the device first, correct?
How exactly is that done?
So what commands do I have to send to calibrate the device? The manual says that I should first test ManufacturerStatus()[CAL] = 0. How do I read the value?

  • hi Hendrik

    ps refer to the app note below on configuring the device. You absolutely have to configure the device using bqstudio. There is no way around this , Though app note is written for a different sister device, it is applicable to this.

    www.ti.com/.../slua777

    For communicating with the gauge using your arduino after you have configured your gauge following the app note above, see app note below:

    thanks

    Onyx