TMS320F28P559SJ-Q1: P55x external voltage reference for ADC setting

HI Jeffrey,

Did you run any of C2000ware examples and still seeing the same issue? Can you send the code here, how is SOCs configured etc...

Thanks,
Susmitha

Hi Susmitha,

The reference code is from TI library 5.02 (adc_ex2_soc_epwm). Only modified "ADC_setVREF(myADC0_BASE, ADC_REFERENCE_EXTERNAL, ADC_REFERENCE_3_3V);" in board.c (copy it from syscfg folder). Same issue.

Thanks,

Jeffrey

Hi Jeffrey,

The easiest way is to use sysconfig file and make changes to either select internal (1.65V/2.5V) or external (3V)

Can you please try this and let me know if the problem still exists.

Thanks,
Susmitha

Hi Susmitha,

I follow what you suggested and get same change in ADC_setVREF() with "ADC_REFERENCE_EXTERNAL". Meanwhile, insert 3.09V reference to p15 pin1 and 1.4V to ADCINA0, the ADC result is 926. Unfortunately, it's only half of real voltage. 

Thanks,

Jeffrey

Hi Jeffrey,

Which channels are inputted? Can you send me the code of how SOC is configured?

Thnks,

Susmitha

Hi Susmitha,

I do not change the code (adc_ex2_soc_epwm) except internal or external reference: it's ADCINA0 and SOC0. 

Thanks,

Jeffrey

Hi Susmitha, 

See email thread for shared code from customer side.

Brian Wang

Hi Jeffrey,

On talking to our experts here...We are thinking it might be REV id issue.

To rule out, you are using APL sample Launchpad. Can you confirm the value at address 0x5D00C?

You can also put a break point just after device_init() and confirm if it is reaching that point.

Can you please try above and let me know?

Thanks,
Susmitha

Hi Susmitha,

It's as :

Thanks,

Jeffrey

Hi Jeffrey,

The value above at address 0x5D00C is 1, it means the rev_id is REV0. Device Cal function address is different for different revisions of the
 F28P55x device.

Please make below changes:

• If the revision ID (value at address 0x5D00C) is "1" then define the REV_ID as a predefined symbol in the projectspec and (Add "--define=REV_ID=1" in the compiler flags, which correspond to REV0
• Also,Inside sysctrl.h we defined the location of Device_cal 

           #define Device_cal ((void (void))((uintptr_t)0x003fb1e7)) . please make sure, you have same value.

Thanks,

Susmitha

Hi Susmitha,

I follow your suggestion to (Add "--define=REV_ID=1" ...), and verified " #define Device_cal ((void (void))((uintptr_t)0x003fb1e7)) ". Unfortunately, this solution helps nothing to get correct result.

Thanks,

Jeffrey