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ADS7951-Q1: Questions about GPIO configuration of ADS7951

Chuqiang Wen
Expert 4580 points
Part Number: ADS7951-Q1
Other Parts Discussed in Thread: ADS7951

Hi Expert,

Customer is now using TI’s ADC sampling chip ADS7951. GPIO1 should be programmed as general purpose output (GPO) function.

The configuration process shows as following:

Step 1: The register are setting as the Table 11. The command is 0X4002.

0x4002 means:

Bit 15-12 = 4 -> GPIO Pegister programming
Bit 11-10 = 0 -> OK (reserved)
Bit 9 = 0 -> Normal operation
Bit 8 = 0 -> GPIO3 is GPIO
Bit 7 = 0 -> GPIO2 is GPIO
Bit 6-4 = = -> GPIO1 and GPIO0 are GPIO
Bit 3 = 0 -> GPIO3 is an input
Bit 2 = 0 -> GPIO2 is an input
Bit 1 = 1 -> GPIO1 is an output
Bit 0 = 0 -> GPIO0 is an input

Step 2: Set Gpio1 to high

The register are setting as the Table 1. The command is 0X1812.

0x1812 means:

Bit 15-12 = 1 -> Manual Mode
Bit 11 = 1 -> Programming of Bits 0-6 enabled
Bit 10-7 = 0 -> next channel is 0
Bit 6 = 0 -> Selects 2.5V i/p range
Bit 5 = 0 -> normal operation
Bit 4 = 1 -> Bits 15-12 of  response are gpio values
Bit 3-0 = 2 -> Gpio 1 shall be high

But it failed to configure the GPIO1 to output and set it to high. (customer also read back the individual bits of the register and it shows the bits are setting successfully.)

Please help analysis what is the problem with the above settings? 

Thanks!

Ethan Wen

  • +1
    TI__Mastermind 22950 points

    Hi Ethan,

    Thank you for posting on our forums!

    I double checked the commands the customer sent (0x4002 and 0x1812) on an EVM and I was able to toggle and identify that GPIO1 was being properly configured. Since the customer is having some trouble doing so, can you please answer the following questions?

    • Is the customer using an EVM or their own custom board? If using a custom board, can you pleases provide a schematic?
    • Have all of the power supplies and reference voltages been monitored? Are the supplies clean?
    • Was GPIO1 begin monitored by a multimeter to confirm that there is no activity?
    • Is there any trouble reading conversion results from the ADC?

    Regards,

    Aaron Estrada

  • 0 in reply to Aaron Estrada
    TI__Expert 4580 points

    Hi Aaron,

    Thanks for your support.

    Please see the feedback as below. 

    Aaron Estrada said:
    Is the customer using an EVM or their own custom board? If using a custom board, can you pleases provide a schematic?

    Using their own custom board. Please find the schematic as below. 

    Aaron Estrada said:
    Have all of the power supplies and reference voltages been monitored? Are the supplies clean?

    The power supply and reference voltage are good.

    Aaron Estrada said:
    Was GPIO1 begin monitored by a multimeter to confirm that there is no activity?

    Yes. After configuring the resistors, they have checked the output of GPIO1 by multimeter. And it is no activity. 

    Aaron Estrada said:
    Is there any trouble reading conversion results from the ADC?

    The conversion results from the ADC can be read correctly. There is no problem. 

    Regards,

    Ethan Wen

  • 0 in reply to Chuqiang Wen
    TI__Mastermind 22950 points

    Hi Ethan,

    I don't see any issues with the GPIO pins. I do see that the other GPIOs are being used as well. Are there any issues with the other GPIOs or is it just GPIO1? After writing to the manual mode register to set GPIO1 high, the GPIO should toggle after the command is sent. Like I mentioned in my previous post, I was able to toggle GPIO1 using the same commands. 

    Regarding the schematic, is GPIO1 connected anywhere else off page?

    Regards,
    Aaron

  • 0 in reply to Aaron Estrada
    TI__Expert 4580 points

    Hi Aaron,

    Thanks for your great support. 

    Per customer's feedback, the problem is solved. The failure is caused by other parts of the system.

    Regards,

    Ethan Wen