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AFE 031 doubt

Victor Perone
Prodigy 30 points

Other Parts Discussed in Thread: AFE031

Hi,

I am trying to interface the AFE031 via SPI to control the DAC. I can write and read from the registers and So far according to the logic analyzer and the obtained values I am doing it correct.

I can read and write information on the registers, I have setted:

                                           MSB            LSB

 Enable1 Register - >      - - 1 1 0 0 1 1

Gain Select Register ->   - - 1 1 0 0 0 0

Enable2 Register ->         - - - - 1 1 1 0

Control1 Register ->        - - - - 0 1 0 1

Control2 Register -> Default

RESET Register -> Default

I took care on the sequence to write at DAC:

• Set CS low.

• Set the DAC pin (pin 7) high.

• Write a 10-bit word to DIN. The DAC register is left-justified and truncates more than 10 bits.

• Updates the DAC output by driving CS high.

 

but observing the output of the DAC on pin 14 after it has gone through the Tx_PGA is almost random.

when I read the Control1 Register the following sequence appears: 0 0 0 1 0 1 0 1 indicating that the TX block is not ready For transmission. 

suggestions about which is my problem and how to solve it?

  • 0
    TI__Genius 9975 points

    Hello Victor Perone,

    The problem in your procedure might be your settings for Control1 Register. You are placing the TX signal chain in the calibration mode; in such mode, internal switches channel the signal generated by the DAC into the output of RX_PGA2 (meant to be injected into the ADC of a microcontroller for calibration purposes).

    My recommendation would be to leave the three least significant bits of Control1 Register in the "0" value.

    Hope this helps.

    Best regards,

    Jose

  • 0 in reply to Jose Duenas
    Prodigy 30 points

    Hello Jose Cuellar,

    thanks for the suggestion but did not worked.

    I left the three least significant bits of Control1 Register in the "0" value as recomended but the result is still the same.

  • 0 in reply to Jose Duenas
    Prodigy 30 points

    I am trying to do incremental tests on the AFE031, so the circuit that I am using is the following one:

  • 0 in reply to Victor Perone
    TI__Genius 9975 points

    Hello Victor Perone,

    At this point all I can offer is to review the signals in your SPI bus. I will be happy to check the signals you are transferring onto the AFE031; please include the signals on the DIN, SCLK, CS and DAC pins with the oscilloscope probes as close as possible to the AFE031.

    Best regards,

    Jose