LAUNCHXL-F28069M: ADC Result registers showing 4096 in Debugging mode.

Prabhjot,

What voltage are you placing on the ADC pin to convert?

-Tommy

Hello Tommy,

I am not giving them any input(ifloating). I also grounded ADC inputs, the values stay frozen at 4096 anyhow.

Prabhjot 

Prabhjot,

The ADC converter has undefined results when the pins are floating.  The values can vary anywhere within the full scale range.

The adc_soc example will only convert ADCINA2 and ADCINA4.  Are you driving those specific pins to GND?

-Tommy

Hello Tommy,

I am driving those to specific pins to ground. When I pause and resume the debugger, I see that my program is stuck at line 380 which has following line of code in F2806x_Adc.c.

while (AdcRegs.ADCINTFLG.bit.ADCINT2 == 0)
{

}

All the registers have 0x0FFF value. It is waiting for adc interruot 2 to trigger which is not getting triggered i think.

Regards

Prabhjot

Hi Prab,

Is this the same project: C:\ti\c2000\C2000Ware_1_00_01_00\device_support\f2806x\examples\c28\adc_soc with no modifications?

Regards,
Gautam

Hello Gautam

Yes it is the same one without any modifications.

Prabhjot,

Please try this:

1. Unplug your LaunchPad
2. Set BOOT dip switch (S1) to Emulation Boot by setting TRST (Position 3) to HIGH.
3. Plug in LaunchPad
4. Load & run adc_soc example

-Tommy

Hello Tommy,

I have been operating the Launchpad in Emulation Boot mode (TRST High). When I use F28069.cmd ( for uploading code in Flash) & run in emulation boot mode, and begin step by step debugging of the microcontroller, the program stays at line 380 of F2806x_Adc.c and ADCRESULT registers show 0x0FFF. 

If I upload the program in RAM and then run in emulation boot mode, the program stays at line 215 of Example_2806xAdcSoc.c and LoopCount  variable has value 46334 and ADCRESULT registers have 0x0FFF.

Prabhjot

Prabhjot,

The RAM execution looks more promising than FLASH.  At least the example is running (LoopCount incrementing) vs stuck. How are you driving the pins to ground?  Can you specify the exact header pins that you are using?

You can also try the "adc_temp_sensor_conv" example.  That does not require any external voltages to be forced onto the pins.

-Tommy

Hello Tommy,

I am driving ADC Pin AA2 and AA4 to ground by using jumpers from ground pins provided on Launchpad.

I tried "adc_temp_sensor_conv" example and watched expressions temp, degC and degK. These are showing values 4095, 410 and 683 respectively. Program execution is stuck at line no. 186 (Waiting for ADCINT1).

-Prabhjot

Tommy,

Can you  please pin point the IC that could have been damaged? Or is the board irreparable? because I cannot afford spending again on a new Launchpad Board.

Prabhjot

Prabhjot,

It is difficult to identify the exact problem remotely, but I am thinking that either:

1. VDDA and VSSA are not getting to the F28069 device pins, or
2. The analog circuitry inside the F28069 is damaged

The temperature sensor example is written to use all internal resources (ex: clocks, ADC reference, and ADC channel).  A failure for that example would suggest one of the above problems.

You may be able to get a replacement if this is a fresh board from an authorized seller.

-Tommy

Thanks a lot Tommy. I will see if I can get a replacement from mouser.

Regards

Prabhjot