ADC SOC Continuous DMA

Table of Contents

• Introduction
  • Errata i2355
• External Connections
  • AM263PX-CC E2 or AM263X-CC E2
  • AM263X-CC E1
  • AM263PX-LP or AM263X-LP
• Supported Combinations
• Steps to Run the Example
• See Also
• Sample Output

Introduction

This example sets up two ADC channels to convert simultaneously. The results will be transferred by DMA into a buffer in RAM.

Module Block diagram

Errata i2355

errata i2355 for AM263x

• DMA trigger from the ADC INT (Late) occurs just before the Result space updation, as a result of which the stale data from the result space will be transferred by DMA.
• Workaround use an empty channel transfer before the Actual transfer.

The example does the below

• Configures ePWM0 to trigger SOC0 on ADC1 and ADC2. This is used to trigger the first ADC conversion.
• INT0 of ADC1 is configured to generate interrupt after first conversion and will then disable EPWM SOC generation.
• Configure ADC INT1 of both ADC's to enable continuous conversion. The interrupts will act as trigger for next conversions.
• Configure DMA channel 0 to be triggered at EOC0 of ADC1 and copy conversion result to an empty buffer, triggerring another channel channel 1 to transfer the ADC result to a result buffer in RAM.
• Configure DMA channel 2 to be triggered at EOC0 of ADC2 and copy conversion result to an empty buffer, triggerring another channel channel 3 to transfer the ADC result to another result buffer in RAM.
• Configure DMA to generate interrupt after the buffer is filled and stop conversion on both ADC's.
• The DMA destination buffers (watch variables) can be used to view the ADC conversion results.

Watch Variables

• gAdc0DataBuffer, gAdc1DataBuffer - Digital representation of the voltage on pin ADC0_AIN0 and ADC1_AIN0

External Connections

• ADC1_AIN0 and ADC2_AIN0 pin should be connected to the signals to be converted.

AM263PX-CC E2 or AM263X-CC E2

• Feed the External Volatage to the following
  • ADC1_AIN0 : HSEC-PIN 12
  • ADC2_AIN0 : HSEC-PIN 31

AM263X-CC E1

• Feed the External Volatage to the following
  • ADC1_AIN0 : HSEC-PIN 18
  • ADC2_AIN0 : HSEC-PIN 24

AM263PX-LP or AM263X-LP

• Feed the External Volatage to the following
  • ADC1_AIN0 : J1/3 24
  • ADC2_AIN0 : J1/3 25

Supported Combinations

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

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 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 Continuous DMA transfer Test Started ...
ADC0 : ADC1 Result register value -
1048 : 1072
1048 : 1072
1048 : 1072
1048 : 1072
1048 : 1072
1048 : 1072
1048 : 1072
1048 : 1072
1048 : 1072
1048 : 1072
1048 : 1072
ADC Continuous DMA transfer Test Passed
All tests have passed!!