CC2640R2F: I2C

William Maire

Part Number: CC2640R2F
Other Parts Discussed in Thread: BQ24725

Dear Sir or Madam,

I'm trying to use I2C to communicate with fuel gauge component. My project (starting from the empty project) isn't working, so I tried to find what was wrong.

I don't understand why, but is when I tried to use the I2C I wasn't able to observe the SCL on an oscilloscope, I am wondering why.

I also try to use the example i2ctmp007 on my CC2640R2Launch XL (linked to nothing but the oscilloscope) but I also wasn't able to observe the SCL signal.

Do you have any idea why and how to correct it.

Kind regards,

William.

over 4 years ago

0 Clément over 4 years ago

TI__Guru** 101490 points

Hi William,

The I2C interface needs external pull-up resistor and does not output any signal if no I2C device is attached.

Please see this page for additional suggestions (applicable to both CC26x2/CC13x2 and CC2640R2). Make also sure to leverage the TI drivers examples provided within your SDK.

Best regards,

0 William Maire over 4 years ago in reply to Clément

Prodigy 250 points

Hi Clément,

Thanks for your answer, I have then attached my I2C device with its pull up resistors added on its eval board. But still I'm trying to do a while(1) with an I2C transaction and nothing seems to happen.

What page are you talking about ?

Kind regards,

+1 Clément over 4 years ago in reply to William Maire

TI__Guru** 101490 points

Hi William,

I am referring to the debugging guide for serial interfaces (even if it is hard to see, there is an hyperlink).

Once again, I recommend to leverage the example i2ctmp rather than starting from scratch.

Regards,

0 William Maire over 4 years ago in reply to Clément

Prodigy 250 points

Okay, thank you Clément.

I'll try to use the i2ctmp example then.

0 William Maire over 4 years ago in reply to Clément

Prodigy 250 points

Hi Clément, I managed to modify the i2ctmp example to work with my fuel gauge. The part that I have been struggling with is the device address. Do you know why the I2C address given in the datasheet of the component as to be shifted to the right ?

Kind regards,

+1 Joe G. over 4 years ago in reply to William Maire

TI__Mastermind 25966 points

Believe this might be a classic 7-bit address confusion. .

I learned (from a colleague) much easier to represent in binary i.e for address 0b00010010 (0x12H)

#define bq24725_addrs 0b0001001

Somewhat demoed here: training.ti.com/rapid-proto-fund-i2c-smbus

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CC2640R2F: I2C