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TPS65950 MADC

J.Sample
Intellectual 690 points
Other Parts Discussed in Thread: TPS65950, OMAP3530

 

I'm currently trying to read VBAT using the TPS65950 on a custom OMAP3530 board and am running into some problems.  I'm using the madc software that was included in the WinCE 6.0 BSP.   When I run the software on the Mistral EVM using the TPS65950 ADC it works fine and I get a voltage level back, but when I run the same software on our board I read back 0V every time.  I've tried reading from ADCIN4 just to try another input and got the same results, always 0V regardless of the input on my board and a non zero value on the EVM.

Since the same SW is working on the EVM and not our board I’m guessing the issue is with the HW – what in HW would cause this to happen?  Any ideas?

Thanks.

 

  • 0
    Intellectual 690 points

    Ok nevermind I found the solution here: https://community.ti.com/forums/t/3265.aspx

    GPBR1 was the culprit.  It's definitely effected by the sysboot settings - I had the EVM set to (UART3, OneNAND) and changed it to (USB, UART3, MMC1, OneNAND), which is what I had on my board, and it caused the GPBR1 register to be set to 0 at boot.  I'm guessing the USB option uses the MADC to check for a valid VBUS and then maybe disables the MADC when it's done with it.