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TPS65072 ADC converter

Hongtao Yan
Intellectual 395 points
Other Parts Discussed in Thread: TPS65072

Hi all,

I am currently attempting to use the AD_IN1-4 pins as a AD converter to detect if a voltage from a seperate device is present. It seems that when I use the AD converter, by setting the TSCMODE register to 110 (A/D measurements) or 111 (TSC and ADC disabled) followed by writing ADCONFIG register with  11010000 (Start AD converstion for AD_IN1 with reference voltage). It seems that when I write to the ADCONFIG register the TSCMODE register changes to usually TSC x-position. This applies the TSREF to AD_IN1, which is undesirable. What way can I use the TPS65072 ADC without the TSC completely disabled?

  • 0
    TI__Genius 16870 points

    Hi, 

    Sorry you are having trouble. I do not see this behavior in the lab. Nor should this not happen.

    Can you send me the register read out of registers: x07 and x08 at every step in your read write procedure?

  • 0 in reply to Michael Green
    Intellectual 395 points

    Here is the readout of the two registers you asked for in some basic operations. The second write is to demonstrate that regardless of what is being written to x07 the value in x08 changes. 

    # pmicr 7
Return Value is 20
# pmicr 8
Return Value is 7
# pmicw 8 6
# pmicr 8
Return Value is 6
# pmicr 7
Return Value is 20
# pmicw 7 C0
# pmicr 8
Return Value is 0
# pmicr 7
Return Value is A0
# pmicw 8 6
# pmicr 8
Return Value is 6
# pmicr 7
Return Value is A0
# pmicw 7 0
# pmicr 8
Return Value is 0
# pmicr 7
Return Value is 20

    Also it is worth noting that I am able to get the correct voltages when I write x08 to 6, start conversion in x07 and repeat. The first time I run the conversion the values of the TSCmode is set to x-position and measure TSREF on the AD_IN1 pin. The second time where I rewrite to x08 and x07 I get the correct voltage measurements. The issue with this method is its not clear why this is occuring and TSREF is being applied to AD_IN1 which changes the behavior of the component we attached to AD_IN1.

     pmicw 8 7
 pmicw 7 D0
 pmicw 8 7
 pmicw 7 D0

  • 0 in reply to Hongtao Yan
    TI__Genius 16870 points

    Hi HongTao, 

    I can't replicate your results in the lab. Are you using the GUI and EVM? 

  • 0 in reply to Michael Green
    Intellectual 395 points

    Hi Michael,

    It seems that when I perform the same measurements on the EVM I am obtaining the correct results. It is only when I run the conversion in my implementation does the AD conversion seem to switch to touch panel mode. Here is the connections that I am using.

    Thanks

  • 0 in reply to Hongtao Yan
    TI__Genius 16870 points

    Hi Hongtao,

    I don't know what could cause this therefore, I don't know what to look for in the schematic.

    1. Can you try on your setup to read from x08 before writing to it? It should be 111 by default.
    2. Can you solder the SDA, SCL, and GND line from the USB2GPIO box to your board. Use our GUI and run through the same test to eliminate either the software or hardware.
    1. If the GUI and your hardware works properly then, we can eliminate the hardware and focus on the software. Otherwise, if you get the same result then we focus on the hardware.

  • 0 in reply to Michael Green
    Intellectual 395 points

    Hi Michael,

    After testing the setup with the GUI it seems that the issue was in the software implimentation of the I2C connection, and it has now been fixed. Thank you for your help.

    Best Regards,

    Hongtao