ADC Differential Mode

Table of Contents

• Introduction
• External Connections
  • AM263X-CC
  • AM263X-LP
• Supported Combinations
• Steps to Run the Example
• See Also
• Sample Output

Introduction

This example sets up ePWM0 to periodically trigger a set of conversions (SOC0,1) on ADC0 for conversion of inputs on ADC_AIN0, ADC_AIN1 in differential modes (ADC_AIN0 - ADC_AIN1) on SOC0 and (ADC_AIN1 - ADC_AIN0) on SOC1.

Note:

• In differential mode, the outputs are symmetric across "2112 or 0x840".
• if there is a +1v on differential input, expected output should be around 2752 or 0xAC0.
• if there is a -1v on differential input, expected output should be around 1472 or 0x5C0.
• Expect wrapping of output if the readings are above 3.2v

ADC0 Interrupt ISR is used to read results of ADC0 (i.e. digital representations of inputs ADC_AIN0, ADC_AIN1 and average of oversampled ADC_AIN3)

The below watch variables can be used to view ADC conversion results.

Watch Variables

• gAdc0Result0 - Digital representation of the differential voltage on pins ADC0_AIN0 - ADC0_AIN1
• gAdc0result1 - Digital representation of the differential voltage on pins ADC0_AIN1 - ADC0_AIN0

The example does the below

• Configures SOC0,1,2 of ADC0, as high priority SOCs, to be triggered by EPWM0.
• Configures ADC interrupt 0 to be generated at end of conversion of SOC12.
• ADC0 Interrupt ISR is used to read results of ADC0 from SOC0,SOC1 and average of SOC12 through SOC15.

External Connections

• ADC0_AIN0, ADC0_AIN1 pins should be connected to signals to be converted in differential mode.

AM263X-CC

When using AM263x-CC with TMDSHSECDOCK (HSEC180 controlCARD Baseboard Docking Station)

• Feed analog inputs (non-zero voltage) to HSEC Pin 12, HSEC Pin 14

AM263X-LP

When using LP

• Feed analog inputs (non-zero volatage) to Boosterpack header Pin 23,Pin 28.

Supported Combinations

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

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.
• View the ADC conversion results in UART console logs

See Also

ADC

Sample Output

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

ADC EPWM Triggered Differential Mode Conversions Test Started ...
ADC0 SOC0 : SOC1
2111 : 2185
1594 : 2627
1603 : 2620
1603 : 2620
1602 : 2620
1602 : 2621
1604 : 2619
1594 : 2627
1603 : 2621
1603 : 2620
1603 : 2620
ADC Differential Mode Test Passed
All tests have passed!!