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BQ79600EVM: SPI wakeup BQ79616 not waking up

Priya Nadathur
Intellectual 545 points
Part Number: BQ79600EVM
Other Parts Discussed in Thread: USB2ANY, BQ79616, LP-MSP430FR2476

I have the LP-MSP430FR2476 SPI wired to the BQ79600 EVM. I have one BQ79616 EVM connected to the BQ79600. The wakeup from the USB2ANY lights up the LED on the BQ79616. With the MSP430, I am seeing the LED on the BQ79600 EVM but not the BQ79616. I can see that SPI_RDY is not going high like it does in the USB2ANY. Why is this?

  • 0
    Intellectual 545 points

    I set the SPI_RDY GPIO as an input pin. This helped with the SPI_RDY levels. However, with the USB2ANY, there is activity on the COMHN pin soon after wakeup (J19-2 on the BQ79600 EVM). This is not happening with the MSP430. 

  • 0 in reply to Priya Nadathur
    Intellectual 545 points

    I needed to look closely at the SPI set up. Finally the LED is on in the BQ79616 EVM.......

  • 0 in reply to Priya Nadathur
    TI__Genius 14890 points

    Priya,

    Sorry for the delay in response. There are a few things that may be happening here, that I’ll list below:

    1. Is the stack device being autoaddressed and woken up? It is not clear from the thread that this is happening correctly. If we could get a list of the commands being sent, we can confirm this.
    2. By default the BQ79616 has a communication timeout enabled. The GUI will automatically set the [COMM_TIMEOUT_CONF] registers to disable the timeout, but if the software doesn’t do this, then you could lose communications unexpectedly.
    3. There may be an issue with error on the daisy chain between the BQ devices. What isolation type are you using on the daisy chain? Capacitor, capacitor and choke, or transformer? Can you share a waveform of the COMH pins to confirm that we the device is receiving an appropriate signals. If these are not high enough, the receiving device will discard the communication packets.
    4. Are there any communication fault flags set? This is another good indicator for what may be the cause of the communication troubles