PDA

View Full Version : TLE9879 Eval Kit onboard ADC Pot Issue.



Litun
Jan 31st, 2018, 01:27 AM
Hello,
I am using TLE9879 Eval Kit V1.2. So i have connected VDDP to JP6 pin no 1(As described in the user manual). And i have confirmed with a scope that in Pin 2.4 the voltage veries from 0V to 5V as
I turn Potentiometer. So potentiometer works fine.

I am using the "ADC1_POTI_EIM_EXAMPLE_TLE987X" from the Examples. And I see that the digital ADC value is 0 at potentiometer null position(Extreme left) and as I turn the potentiometer a just little
it seems like ADC value is 1023.(I could see from the LED behavior). It means at 0V, ADC value is 0 and at 0.3V(instead of 5V), ADC value is 1023. Why?

To confirm, when I check with debugger mode the variable which stores ADC value mV shows <Can not evaluate> in the watch window. Why?

3320

Mc-Key
Jan 31st, 2018, 04:24 AM
Hi,
the example code works fine on my side!
I tested the project on a TLE9879 Evalkit Rev1.2.

Please check, if you use the latest Pack file. (Version 1.3.2)

Please try the project I tested:
3325
The LEDs should act like a bargraph for the poti position.

It is important to activate VAREF for the ADC1. (ConfigWizard-->ADC1)
In my case it is already enabled in the project.
Of Course, I also had to connect JP6 Pin1 to VDDP.

It is important to remove JP4 for this example. (Evalkit User Manual Chapter 9.1)

Please check, if VAREF Pin has a voltage level of ~5V.

"mV" in the Debug Window:
"mV" is a local variable in the function Poti_Handler().
If you want to track the variable in the watch window, you have two options:
- place a breakpoint in the function
- change "mV" to be a global variable

I'm looking forward for your feedback.

Best Regards,
M.K.

Litun
Jan 31st, 2018, 11:38 PM
Dear M.K.,
Thank you very much for the info.

The VREF shows voltage in millivolts range(not 5V). Found out that VDDEXT is down. Removed JP4. Then VREF is 5V.
The user manual says JP4 to use of VDDEXT. But from the circuit diagram, it true that VDDEXT can affect VREF.

Looking for the possible cause of VDDEXT failure.:(
And thanks for the info about the Global variable in the watch window.