ADC Trigger Repeater Undersampling

Table of Contents

• Trigger repeater module
• Example Description
  • ADC Configurations
  • ISR Configuration
• External Connections
• Supported Combinations
• Steps to Run the Example
• See Also
• Sample Output

Trigger repeater module

The trigger repeater module allows to achieve an oversampling, undersampling or to apply a trigger delay. The repeater modules can select any of the regular ADC triggers that are selectable by ADCSOCxCTL.TRIGGER register and generate a number of repeated pulses as configured in repeater module. The repeater module can apply four types of trigger modifications:

• Oversample mode - allows multiple back-to-back samples from a single trigger pulse.
• Undersample mode - scale down the trigger frequency for one or more SOCs.
• Phase delay - delay the initial trigger by a specified number of SYSCLK.
• Re-trigger Spread - the additional time between two samples.

Example Description

This example configures ADC for undersampling using trigger repeater block. The ePWM0 is configured to periodically trigger the trigger repeater module on ADC1 for conversion of inputs on ADC1_AIN0. The trigger repeater module is condifured to generate 1 pulse out of 4 pulses.

ADC Tigger Repeater Undersampling

ADC Configurations

1. Trigger repeater module on ADC1 is triggered by EPWMSOCA
2. SOC0 will be triggered by trigger repeater and Sample window is set at 16

1. SOC0 samples on channel 0 and trigger source is set as repeated trigger
2. Trigger repeater module 1 is configured for undersampling
3. Trigger count (N) is set to 3, so it will generate 1 out of N+1 pulses

ISR Configuration

1. INTXbar0 is set for EPWM0INT
2. App_epwmISR services this interrupt
   • reads ADC EOC flag

External Connections

ADC1_AIN0 pin should be connected to signals to be converted.

• on AM263Px CC E1 or AM261x-SOM E1, with HSEC Dock
  • Feed Analog input to ADC1_AIN0 - HSEC PIN 12
• on AM263Px LP / AM261x LP
  • Feed Analog input to ADC1_AIN0 - J1/3 Pin 24

Supported Combinations

Parameter	Value
CPU + OS	r5fss0-0 nortos
Toolchain	ti-arm-clang
Board	am263px-cc, am263px-lp
Example folder	examples/drivers/adc/adc_trigger_repeater_undersampling/

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 running,

ADC Trigger Repeater Undersampling Test Started...
ADC Trigger Repeater Undersampling results:
Trigger Repeater Undersampling Test Passed!!
All tests have passed!!