Arduino for STM32

Code: Select all

#include <Arduino.h>

uint16_t pulse[80];
uint8_t data[5];

bool debug=false;
const uint8_t dht_data_pin = PB7;
uint8_t tog = 0;
bool timeout = false;

uint16_t expectPulse(uint8_t val);
void prtemp();
void timer_handler();
void dht_read();
float get_humidity();
float get_temp();
bool check_parity();
void sleep(uint16_t ms);

void setup() {
	pinMode(LED_BUILTIN, OUTPUT);
	Serial.begin();
	// vrefint
	adc_reg_map *regs = ADC1->regs;
	regs->CR2 |= ADC_CR2_TSVREFE;    // enable VREFINT and temp sensor
	regs->SMPR1 = ADC_SMPR1_SMP17;  // sample rate for VREFINT ADC channel

	//initialise microsecond timer
	Timer1.init();
	Timer1.pause();
	Timer1.setPrescaleFactor(72-1); // 1 us
	Timer1.setOverflow(0xffff); //timeout 65.535 ms
	Timer1.attachInterrupt(0, timer_handler);
	Timer1.refresh();

	pinMode(dht_data_pin, INPUT_PULLUP);
}

void timer_handler() {
	timeout = true;
	Timer1.pause();
}

void loop() {
	digitalWrite(LED_BUILTIN, HIGH);
	sleep(100);
	digitalWrite(LED_BUILTIN, LOW);

	prtemp();
	dht_read();
	float hum = get_humidity();
	float temp = get_temp();
	Serial.print("dht humidity (RH%):");
	Serial.println(hum);
	Serial.print("dht temp (C):");
	Serial.println(temp);
	sleep(10000);

}

void sleep(uint16_t ms) {
	for(int i=0; i<ms; i++)
		asm("wfi");
}

float get_humidity() {
	uint16_t hum = data[0] << 8 | data[1];
	return hum / 10.0;
}

float get_temp() {
	int temp = (data[2] & 0x7f) << 8 | data[3];
	if(data[2] >> 7 == 1)
		temp *= -1;
	return temp / 10.0;
}

bool check_parity() {
	uint8_t sum = data[0] + data[1] + data[2] + data[3];
	return sum == data[4];
}

/* note the timings used here is based on DHT22 AM2302
 */
void dht_read() {
	pinMode(dht_data_pin, OUTPUT_OPEN_DRAIN);
	digitalWrite(dht_data_pin, LOW);
	delay(1); //start conversion 1ms low pulse
	digitalWrite(dht_data_pin, HIGH);
	pinMode(dht_data_pin, INPUT_PULLUP);
	expectPulse(HIGH); //30us
	if(timeout) {
		Serial.println("timeout waiting for response low");
		return;
	}
	expectPulse(LOW); //80us
	if(timeout) {
		Serial.println("timeout waiting for response high");
		return;
	}
	expectPulse(HIGH); //80us
	if(timeout) {
		Serial.println("timeout waiting for data");
		return;
	}
	/* next data pulses
	 * low pulse 50 us
	 * '0' high pulse 26 us
	 * '1' high pulse 70 us
	 */
	for(uint16_t i=0; i<80; i+=2) {
		pulse[i] = expectPulse(LOW);
		if(timeout) {
			Serial.print("timeout reading data ");
			Serial.print(i/2);
			Serial.println("low");
			return;
		}
		pulse[i+1] = expectPulse(HIGH);
		if(timeout) {
			Serial.print("timeout reading data ");
			Serial.print(i/2);
			Serial.println("high");
			return;
		}
	}
	//decode pulses
	for(uint16_t i=0; i<40; i++) {
		uint16_t lowcount = pulse[2*i];
		uint16_t highcount = pulse[2*i + 1];
		if(debug) {
			Serial.print(i);
			Serial.print(":");
			Serial.print(lowcount);
			Serial.print(",");
			Serial.println(highcount);
		}
		data[i / 8] <<= 1;
		if (highcount > lowcount) {
		   // High cycles are greater than 50us low cycle count, must be a 1.
		   data[i / 8] |= 1;
		}
	}
}

uint16_t expectPulse(uint8_t val) {
	//start the counter
	Timer1.refresh();
	timeout = false;
	Timer1.resume();
	while(digitalRead(dht_data_pin) == val && !timeout);
	Timer1.pause();
	return Timer1.getCount();
}

void prtemp() {
	uint16_t vrefint = adc_read((adc_dev *)ADC1, 17);
	Serial.print(F("Vref int (1.2v):"));
	Serial.print(vrefint);
	Serial.println();

	uint16_t vtemp = adc_read((adc_dev *)ADC1, 16);
	Serial.print(F("temp sensor:"));
	Serial.print(vtemp);
	Serial.println();

	uint16_t mv = (1200 * vtemp) / vrefint;
	Serial.print(F("mvolt:"));
	Serial.print(mv);
	Serial.println();

	// specs 5.3.19 temp sensor characteristics
	// V 25 deg ~ 1.43v
	// slope 4.3 mv/C
	float temp = (mv - 1430) * 1.0 / 4.3 + 25.0;
	Serial.print(F("temp:"));
	Serial.print(temp);
	Serial.println();
}

Code: Select all

Vref int (1.2v):1496
temp sensor:1831
mvolt:1468
temp:33.84
dht humidity (RH%):81.60
dht temp (C):30.40
Vref int (1.2v):1504
temp sensor:1835
mvolt:1464
temp:32.91
dht humidity (RH%):81.70
dht temp (C):30.40
Vref int (1.2v):1495
temp sensor:1830
mvolt:1468
temp:33.84
dht humidity (RH%):81.70
dht temp (C):30.40
Vref int (1.2v):1494
temp sensor:1830
mvolt:1469
temp:34.07
dht humidity (RH%):81.70
dht temp (C):30.30

Code: Select all

pinMode(dht_data_pin, OUTPUT_OPEN_DRAIN);
pinMode(dht_data_pin, INPUT_PULLUP);
digitalRead();
digitalWrite();