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TDC7200: Never gives me INTB interrupt

Debora Magliano
Prodigy 30 points
Part Number: TDC7200
Other Parts Discussed in Thread: TDC1000,

Hi!

I have a problem with the TDC, it doesn´t matter how i configure it, never gives me an interrupt change in the INTB pin.

I have  a TDC1000 conected to the TDC7200, and it works well. When the TDC7200 put the Trigger signal in the TRIGGER pin, the TDC1000 makes the mesure with the corresponding START and STOPS signals.

Both, TDC1000 and TDC7200 are configured for two STOP signals and I see everything in my osc. The problem is that the INTB pin dosen´t go down, not even by an overflow of the counter, It does nothing after the trigger signal.

This is my current configuration of the registers of the TDC7200:

CONFIG1 = 0b00111010

CONFIG2 = 0b00000001

INT_MASK = 0b00000111

Everything else is default. I have a pull-up resistor in INTB to 3.3V. The mesure of the TDC1000  takes about 20-40uS. I had chek all the times based on the datasheet and they are good.

Thanks! and sorry for my bad english.

  • 0
    TI__Mastermind 31655 points
    Hello Debora,

    Are you making sure to set the Start New Measurement bit in the TDC7200 via SPI to start the trigger signal? It will not pull the INTB pin low unless the measurement has been started in this way. Also, do you have interrupts enabled in the microcontroller?

    Regards,
  • 0 in reply to Scott Cummins
    Prodigy 30 points

    Hi Scott!!

    I am sure that the Start New Measurement bit is being set. After i write the bit the TRIGGER signal shows up in the TRIGGER pin, and with the falling edge of the START signal the TRIGGER signal also fall down. I supose that the START signal is being acepted by the TDC7200 becasuese of that. The real problem is that no matter what happend after that, INTB dosen´t fall, not even by a overflow of the counter,

    Answering your ohter question, i have an interrupt enebled in the microcontroller, shuted for any falling edge (separately tested).

    Regards,

    Débora

  • 0 in reply to Scott Cummins
    Prodigy 30 points
    Hi Scott, as i try to explain before, my problem could sum up to this.
    In the TDC7200 datasheet, page 20, 8.4.6 Measurement Sequence:

    "8. After the last STOP trigger has been received, the TDC will signal to the MCU via interrupt (INTB pin) that
    there are new measurement results waiting in the registers. START, STOP and TRIGG pin are disabled (in
    Multi-Cycle Averaging Mode, the TDC will start the next cycle automatically by generating a new TRIGG
    signal). Note: INTB must be utilized to determine TDC measurement completion; polling the INT_STATUS
    register to determine measurement completion is NOT recommended as it will interfere with the TDC
    measurement."

    Nothing of this hapend, never. All befote this is well.

    In my first post i said that my config was:
    CONFIG1 = 0b00111010
    CONFIG2 = 0b00000001
    INT_MASK = 0b00000111
    this is because i first write the configuration and after that, i write
    CONFIG1 = 0b00111011
    to start the new mesure.

    I hope that you can understand the my problem. Thnaks!