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ADS1248: ADS1248 GPIO Configuration

Thomas POINSOT
Prodigy 20 points
Part Number: ADS1248

Hi,

I'm actually working on the ADS1248 ADC. For my application i need a high level on the pin 14 ( AIN5/GPIO5). The SPI  work well, i can read/write registers but i have difficulties to setup the GPIO5 to output high level state.

Here my procedure :

- Reset the chip by pull down the reset pin during 10ms

- Wait 1s

- Pull start pin to high

- Wait for DRDY falling edge

- Send SDATAC cmd

- Wait for DRDY falling edge

- Write GPIOCFG to 0x20  (GPIO5 bit set to 1 to use the pin as a GPIO )

- Write GPIODIR to 0x00 (GPIO5 bit to 0 for output mode)

- Write GPIODAT to 0x20 (GPIO5 bit to 1 for a high level)

Bellow traces of the SPI communication. I think I forget something but I do not know what.

Best regards

Thomas

SDATAC cmd :

WREG

  • 0
    TI__Guru** 113765 points

    Hi Thomas,

    Welcome to the E2E forum!  I don't see anything incorrect with the register write.  Have you tried verifying with a register read of the same three registers?  The GPIO functionality is not with the digital side of the device, but rather the analog.  The output voltage levels are with respect to the analog supply voltage, AVDD/AVSS.  When writing the registers you must also make sure the START pin is in a logic high state or the write will not take place.

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    Prodigy 20 points
    Hi,
    My problem is that this GPIO drive the EN pin of my regulator, who supply the analog part of the ADS1248.... It's normal that it does not work...: )
    I will process some modifications on my circuit.
    Thanks for your help !