Add, SMT32ADC example, Single channel at fixed sample rate (timer) using circular buffer (DMA)

STM32F1/libraries/STM32ADC/examples/SingleChannelAtSampleRateCircularBuffer/SingleChannelAtSampleRateCircularBuffer.ino

@@ -0,0 +1,87 @@
+#include <HardwareTimer.h>
+#include <STM32ADC.h>
+
+#define pinLED  PC13
+#define pinOUT  PB0
+
+#define _SEND_BY_USB
+#ifdef SEND_BY_USB
+USBSerial usb;
+#endif
+
+// Channels to be acquired. 
+// A0 (adc1 channel 1)
+uint8 pins = 0;
+
+#define maxSamples  2000
+uint16_t buffer[maxSamples];
+uint16_t *buffers[2];
+uint8_t bufr;
+uint8_t bufw;
+
+#define sampleFreqKhz       200
+#define samplePeriodus      1000 / sampleFreqKhz
+#define ticksPerSecond      2 * sampleFreqKhz * 1000 / maxSamples
+
+
+STM32ADC myADC(ADC1);
+
+
+long ticks;
+void TimerIRQ(void) {
+  ticks++;
+}
+void DmaIRQ(void) {
+  digitalWrite(pinOUT, ! digitalRead(pinOUT));
+  bufw = (bufw+1)%2;
+  ticks++;
+}
+
+void setup() {
+  
+  pinMode(pinLED, OUTPUT);
+  pinMode(pinOUT, OUTPUT);
+  pinMode(pins, INPUT_ANALOG);
+
+  Serial.begin(115200);
+  Serial.println("START");  
+
+  #ifdef SEND_BY_USB
+  usb.begin();
+  while (!usb.isConnected()) ;
+  #endif
+
+  ticks = 0;
+  bufr = 0;
+  bufw = 0;
+  buffers[0] = &buffer[0];
+  buffers[1] = &buffer[maxSamples/2];
+
+  Timer3.setPeriod(samplePeriodus);
+  Timer3.setMasterModeTrGo(TIMER_CR2_MMS_UPDATE);
+
+  myADC.calibrate();
+  myADC.setSampleRate(ADC_SMPR_1_5); // ?
+  myADC.setPins(&pins, 1);
+  myADC.setDMA(buffer, maxSamples, (DMA_MINC_MODE | DMA_CIRC_MODE | DMA_HALF_TRNS | DMA_TRNS_CMPLT), DmaIRQ);
+  myADC.setTrigger(ADC_EXT_EV_TIM3_TRGO);
+  myADC.startConversion();
+}
+
+void loop() {
+
+  if (bufr!=bufw) {
+    // process data 
+    
+    #ifdef SEND_BY_USB
+    if (usb.isConnected()) usb.write((uint8_t *)buffers[bufr],maxSamples); // send it : (maxSamples /2 )*2 (bytes)
+    #endif
+
+    bufr = (bufr+1)%2;
+  }
+  
+  if (ticks==ticksPerSecond) {
+    digitalWrite(pinLED, ! digitalRead(pinLED));
+    ticks = 0;
+  }
+}