I wanted to use the ADC with DMA in Arduino with my STM32F411 Black Pill processor together with my Arduino Audio Tools!
Unfortunately STMDuino does not provide this functionality.
My first trials failed miserably using the DMA versions of the HAL API, so I decided to generate a working solution using the STM Cube IDE and then convert this to Arduino library, that provides the following functionality:
- The DMA is used to transfer the data
- Optionally we can use a timer to define the sampling rate
- The API is using Callbacks to transfer the data or you can call the analogRead() instance method.
- max 8 input channels
- Only 16bit data is supported
- We can normalize the data so that the avg is displayed as 0 (this is e.gl usefull for audio)
- Please note that this functionality deactivates the standard implementation of analogRead()!
| PINs | FUNCTIONs |
|---|---|
| PA0 | Channel0 |
| PA1 | Channel1 |
| PA3 | Channel2 |
| PA4 | Channel3 |
| PA5 | Channel4 |
| PA6 | Channel5 |
| PA7 | Channel6 |
| PB0 | Channel7 |
Below I demonstrate the basic API provided by this library.
#include "AnalogReaderDMA.h"
const int sample_rate = 8000;
const int channels = 2;
const int buffer_size = 1024;
void writeData(int16_t *data, int sampleCount);
// DMA with timer and defined sample rate
AnalogReaderDMA adc(channels, TIM3, sample_rate, writeData, 1024);
// data callback
void writeData(int16_t *rec, int sampleCount){
}
void setup() {
Serial.begin(115200);
while(!Serial);
adc.setCenterZero(true); // optional: we treat it as audio data
adc.begin();
}
void loop() {
}
The preferred way to read the data in continuous mode is by using analogRead();
#include "AnalogReaderDMA.h"
// define continuous mode adc w/o timer
const int channels = 2;
AnalogReaderDMA adc(channels);
void setup() {
Serial.begin(115200);
while(!Serial);
adc.begin();
}
void loop() {
for (int j=0; j<channels; j++){
Serial.print(adc.analogRead(j));
Serial.print(" ");
}
Serial.println();
}
Here is the link to the actual documentation.
You might also find further information in my Blogs
You can download the library as zip and call include Library -> zip library. Or you can git clone this project into the Arduino libraries folder e.g. with
cd ~/Documents/Arduino/libraries
git clone https://github.com/pschatzmann/stm32f411-adc
I recommend to use git because you can easily update to the latest version just by executing the git pull command in the project folder.
Copyright © 2022 Phil Schatzmann
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