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Original question:

AM2634-Q1: Sysconfig enables internal reference by default and ADC_VREFHI_G0/G1 should not connect to ADC_VREFHI_G2 directly...

AM2634: Configuration of ADC with external reference

Donggu Kang
Prodigy 65 points

Part Number: AM2634
Other Parts Discussed in Thread: SYSCONFIG

I am writing to ask you a question about the ADC.

According to the TRM, the ADC can operate using both an internal reference and an external reference.

I would like to know how to configure the ADC to operate using an external reference.

I have attached a screenshot of the auto-generated code from Sysconfig about ADC reference.

As I understand the code, it enables the internal reference for ADC operation.

However, there is no API to disable the internal reference.

.

I asked a specific question about whether I should make an ADC reference disable code for using an external reference.

And is there any hardware configuration for using an external reference ?

Thank you for your time and consideration.

Sincerely,

  • 0
    TI__Guru*** 135355 points

    Hello Donggu,

    Donggu Kang said:

    I would like to know how to configure the ADC to operate using an external reference.

    I have attached a screenshot of the auto-generated code from Sysconfig about ADC reference.

    As I understand the code, it enables the internal reference for ADC operation.

    However, there is no API to disable the internal reference.

    So the external references are enabled by default. If no configuration regarding references are done, the external reference will be used automatically. However if external references are not used, then the SOC_enableAdcReference function needs to be used in order to configure the internal references for use.

    What I don't see initially in SysConfig is a setting to toggle so that the SOC_enableAdcReference isn't called. You can comment it out but it would be good to understand if that can be toggled off with SysConfig or if we need to add that. I'm going to loop in another expert to comment on that piece.

    Donggu Kang said:
    And is there any hardware configuration for using an external reference ?

    As in further configuration than supply a 1.8V ADC reference to a given VREF pair? If so, no it's just a register that determines which is used.

    Best Regards,

    Ralph Jacobi

  • 0 in reply to Ralph Jacobi
    TI__Intellectual 2377 points

    Hi Donggu,

    Assuming you are familiar with Control Card, the SW7 takes care of selecting the ADC-DAC-Vref, refer to the picture below (taken from CC schematics). Based on its position, the external/ internal references can be used. if you set them to the internal, then the SOC_enableAdcReference() API call is mandatory, otherwise can be ignored. 

    thanks,
    Madhava