AM263x MCU+ SDK  09.02.00
ADC PPB Offset

Table of Contents

Introduction

Example Description

This example demonstrates the PPB offset features of Post Processing Blocks of ADC. The PPB offset features are the following,

  1. PPB Calibration Offset
    • This is used for correcting the calibration offset of the selected SOC result.
    • For example, when set the ADC result corresponding to the set SOC ADC_result = ADC_result - PPB Calibration value.
    • If more than one PPB are set for the given SOC, then the result with higher value after calculation will be implemented.
  2. PPB Reference Offset
    • This can be used to calculate an offset from a given reference.
    • The result will be specific to the PPB registers and is stored seperately from the SOC result.
    • For example, when set, the PPB result corresponding to the set SOC ADC_result, PPB_result = ADC_result - PPB Reference value.
    • If "Twos complement mode" is selected, then, PPB_result = PPB Reference value - ADC_result

SOC Configurations

ADC SOC0 and SOC1 are set for Channel 0, with sample window 17 each and are triggered by only software.

PPB Configurations

  1. PPB1
    • Set to SOC1
    • Calibration Offset Value is set to -100
    • Reference Offset Value is set to 0
    • Twos Complement mode is disabled
  1. PPB2
    • Set to SOC1
    • Calibration Offset Value is set to 50
    • Reference Offset Value is set to 50
    • Twos Complement mode is disabled
  1. PPB3
    • Set to SOC1
    • Calibration Offset Value is set to 100
    • Reference Offset Value is set to 50
    • Twos Complement mode is enabled

Interrupt Configurations

  • ADC1_INT1 is set to EOC/SOC1.

External Connections

AM263PX-CC E2 or AM263X-CC E2

  • Feed Analog Input to ADC1_AIN0, HSEC Pin 12

AM263X-CC E1

  • Feed Analog Input to ADC1_AIN0, HSEC Pin 18

AM263PX-LP or AM263X-LP

  • Feed Analog Input to ADC1_AIN0, J1/3 Pin 24

Watch Variables

  • gAdc1Soc0Result[] holds the digital representation of the Analog signal on ADC1_AIN0
  • gAdc1Soc1Result[] holds the digital representation of the Analog signal on ADC1_AIN0 with Calibration offset
  • gAdc1PPB1Result[] holds the digital representation of the Analog signal on ADC1_AIN0 with Calibration offset with Reference Offset of 0
  • gAdc1PPB1Result[] holds the digital representation of the Analog signal on ADC1_AIN0 with Calibration offset with Reference Offset of 50
  • gAdc1PPB1Result[] holds the digital representation of the Analog signal on ADC1_AIN0 with Calibration offset with Reference Offset of 50 and Twos complement enabled.

Supported Combinations

Parameter Value
CPU + OS r5fss0-0 nortos
Toolchain ti-arm-clang
Board am263x-cc, am263x-lp
Example folder examples/drivers/adc/adc_ppb_offset/

Steps to Run the Example

  • When using CCS projects to build, import the CCS project for the required combination and build it using the CCS project menu (see Using SDK with CCS Projects).
  • When using makefiles to build, note the required combination and build using make command (see Using SDK with Makefiles)
  • Establish connections as mentioned in External Connections section
  • Launch a CCS debug session and run the executable, see CCS Launch, Load and Run
  • Using the watch variables, view the ADC conversion results.
  • Observe 6 EPWM waveforms. After ADC input voltage exceeds the PPB limit, PWMs get tripped.

See Also

ADC

Sample Output

Shown below is a sample output when the application is run,

ADC PPB Offset Test Started
SOC0 SOC1(SOC0 result + calibration offset) PPB1(SOC1 result) PPB2(SOC1 result + ref offset) PPB3(PPB2 result in 2's complement)
777 675 675 625 -625
776 675 675 625 -625
772 674 674 624 -624
776 676 676 626 -626
776 676 676 626 -626
775 675 675 625 -625
775 674 674 624 -624
777 675 675 625 -625
ADC PPB Offset Test Passed
All tests have passed!!