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Original question:

TMS320F280039C: I2C Clock line staying low which is either a symptom or a cause of i2c lockup

TMS320F280025C: f280025c i2c slave stuck after flashing

Mark Nordstrand2
Prodigy 10 points

Part Number: TMS320F280025C

Custom board with a msp430 controlling the bus.  Targets include a f280025c and other devices.  Cold boot and everything works fine.  After flashing the f280025c bus locks up with both SCL and SDA pulled low.  If a debugging session is started, SCL get pulled low until the MSP addresses a different device (expected, since the f280025c's address is NACKed (and clock stretched?)).  Starting the debugger both SCL and SDA stay low.  

Of note, the f280025c is using the internal oscillator and GPIO18_X2 and GPIO19_X1 used for i2c.

Tried toggling the configuration of the GPIO's as open drain, but doesn't seem to help.  I there anything else that might clear this up?

 

  • 0
    TI__Mastermind 24811 points

    Hi Mark,

    You mention that the bus is released whenever the MSP430 addresses a difference device, so are you saying that the bus gets locked only when F280025C itself is being addressed? Or that F280025C can lock up the bus even when other device is addressed initially?

    Regards,

    Peter

  • +1
    Prodigy 10 points

    Bus is only locked up after flashing the F280025C or starting a debug session.  Cold start is fine, so only an issue during development.

    But, it turns out it just needed a longer delay between setting those pins as open drain and switching to i2c.