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BQ4050EVM-561: SMBUS Communication with micro processor without ev2300/2400

ruru zhang
Prodigy 30 points
Part Number: BQ4050EVM-561
Other Parts Discussed in Thread: EV2400

Hi,

I am trying to build smbus communication between the bq4050evm board and host microcontroller (stm32).

I used scope to see the clock and data line of smbus, and found that it doesn't acknowledge after the host sending out device address 0x16. 

My hardware wiring is: 

3 series battery connect to N, 1P, 2P, 3P; (10.5V between N pin and 3P pin)

PACK+ connect to 12V power pin on host processor board;

PACK- connect to ground on the host processor board. 

When I push down the LED display. there is no LED turned on, which makes me doubt that the evm is not running. 

Does the evm board have preloaded firmware? Is there a way to tell whether the bq4050evm is running?

And can the evm communicate with other microcontroller through smbus directly? Or is there some configuration should be done to enable it? 

Thanks,

RURU

  • 0
    TI__Mastermind 42535 points
    The evm is a slave, to turn on the evm you must have a pack voltage. You must also have SYS_PRES grounded. Then you can comm with the device. If you have issues and want to check if you have powered on correctly, plug in the device to an ev2400 and see if you can get it to talk. If it does, then you most likely have an issue with your mcu.
  • 0 in reply to Batt
    Prodigy 30 points
    Yes, I connect SYS_PRES to PACK-. If the circuit is powered on correctly, will the leds be turned on when I push the display button? Because I don't have the ev2400 now, is there another way to check whether the board is running?

    Thanks,.
    RURU
  • 0 in reply to ruru zhang
    TI__Mastermind 42535 points
    If your PACK has at least 6V and BATT has 9V and your SYS_PRES is grounded, the gauge will wake up from shutdown. If not, press the wake button and check comms again. That's all you need to check if it's up.
  • 0 in reply to Batt
    Prodigy 30 points

    Thanks for your reply. 

    I have checked the wiring, which looks good.

    But there is one thing I am not sure:

    The Vreg (regulator voltage) = 3.3v, what's the input high voltage and input low voltage for smbus (smbc and smbd)? 

    By the way, do you mind confirm that the device address is 0x16 and clock frequency is 100khz for smbus? 

    Thanks,

    RURU

  • 0 in reply to ruru zhang
    TI__Mastermind 42535 points
    Confirmed for the SMBUS. VIL is 0.8V and VIH is 1.3V typically.