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ADC Pin Mux Registers in Starterware

David Meixner
Expert 4010 points

In Starterware 2.00.01.01, the fileplatform/evmAM335x/tscAdc.c contains the below function. However, the TRM does not define these registers. Is this an omission in the TRM? Should tese calls be made when configuring the ADC?

SOC_CONTROL_REGS = 0x44E1 0000
CONTROL_CONF_AIN0 = 0xB2C

unsigned int TSCADCPinMuxSetUp(void)
{

    HWREG( SOC_CONTROL_REGS + CONTROL_CONF_AIN0) = CONTROL_CONF_AIN0_CONF_AIN0_RXACTIVE;

    HWREG( SOC_CONTROL_REGS + CONTROL_CONF_AIN1) = CONTROL_CONF_AIN1_CONF_AIN1_RXACTIVE;

    HWREG( SOC_CONTROL_REGS +  CONTROL_CONF_AIN2)= CONTROL_CONF_AIN2_CONF_AIN2_RXACTIVE;

    HWREG( SOC_CONTROL_REGS + CONTROL_CONF_AIN3) = CONTROL_CONF_AIN3_CONF_AIN3_RXACTIVE;

    HWREG( SOC_CONTROL_REGS + CONTROL_CONF_AIN4) = CONTROL_CONF_AIN4_CONF_AIN4_RXACTIVE;

    HWREG( SOC_CONTROL_REGS + CONTROL_CONF_AIN5) = CONTROL_CONF_AIN5_CONF_AIN5_RXACTIVE;

    HWREG( SOC_CONTROL_REGS + CONTROL_CONF_AIN6) = CONTROL_CONF_AIN6_CONF_AIN6_RXACTIVE;

    HWREG( SOC_CONTROL_REGS + CONTROL_CONF_AIN7) = CONTROL_CONF_AIN7_CONF_AIN7_RXACTIVE;

    HWREG( SOC_CONTROL_REGS + CONTROL_CONF_VREFP)= CONTROL_CONF_VREFP_CONF_VREFP_RXACTIVE;

    HWREG( SOC_CONTROL_REGS +  CONTROL_CONF_VREFN)= CONTROL_CONF_VREFN_CONF_VREFN_RXACTIVE;
    return TRUE;
}

  • 0
    TI__Intellectual 1980 points

    David,

    I can't answer whether these registers physically exist within the control module, however functionally they don't do anything since the ADC pins are dedicated analog inputs. Essentially that function does nothing and can be removed.

    Regards,

    Tyler

  • 0 in reply to Tyler Berryhill
    Expert 2620 points

    looking into the TRM, It was a mistake made by TI when updating the TRM version.

    Below is the related ADC register information I have extracted from  TRM version e “spruh73e.pdf”.

     

     

     

     

     

  • 0 in reply to WTMEC_Will Hsu
    TI__Expert 4010 points

    I noticed the following statement on this wiki http://processors.wiki.ti.com/index.php/AM335x_Schematic_Checklist#Unused_Signals

    "An exception to above for ADC: keep RXACTIVE=1 for registers CONF_AINx and CONF_VREFP and CONF_VREFN, and connect these signals to ground."

    Given that RXACTIVE=1 by default, and the rest of the fields in the control_module registers are N/A for the ADC pins, I suppose it's pointless to modify these registers (if they exist). I assume that's why it was removed from the TRM.

  • 0 in reply to David Meixner
    TI__Guru* 75990 points

    Hi David, in Rev G of the TRM, we updated the list of pad config registers by removing the irrelevant registers which had no function, of which the ADC registers were included.  I need to remove the statement from the wiki that you cited.

      Regards,

    James