kopia lustrzana https://github.com/SP8EBC/ParaTNC
125 wiersze
2.8 KiB
C
125 wiersze
2.8 KiB
C
#include <stm32f10x_rcc.h>
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#include <stm32f10x_gpio.h>
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#include "../drivers/dallas.h"
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#include "../drivers/dht22.h"
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uint16_t bits[40];
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uint8_t hMSB = 0;
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uint8_t hLSB = 0;
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uint8_t tMSB = 0;
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uint8_t tLSB = 0;
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uint8_t parity_rcv = 0;
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static GPIO_InitTypeDef PORT;
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void DHT22_Init(void) {
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RCC_APB2PeriphClockCmd(DHT22_GPIO_CLOCK,ENABLE);
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PORT.GPIO_Mode = GPIO_Mode_Out_PP;
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PORT.GPIO_Pin = DHT22_GPIO_PIN;
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PORT.GPIO_Speed = GPIO_Speed_50MHz;
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GPIO_Init(DHT22_GPIO_PORT,&PORT);
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}
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uint32_t DHT22_GetReadings(void) {
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uint32_t wait;
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uint8_t i;
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DallasConfigTimer();
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// Generate start impulse for sensor
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DHT22_GPIO_PORT->BRR = DHT22_GPIO_PIN; // Pull down SDA (Bit_SET)
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delay_5us = 175; // delay 875us
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while (delay_5us != 0);
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DHT22_GPIO_PORT->BSRR = DHT22_GPIO_PIN; // Release SDA (Bit_RESET)
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// Switch pin to input with Pull-Up
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PORT.GPIO_Mode = GPIO_Mode_IPU;
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GPIO_Init(DHT22_GPIO_PORT,&PORT);
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// Wait for AM2302 to start communicate
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delay_5us = 80;
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while ((DHT22_GPIO_PORT->IDR & DHT22_GPIO_PIN) && (delay_5us > 0));
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if (delay_5us < 10) return DHT22_RCV_NO_RESPONSE;
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// Check ACK strobe from sensor
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delay_5us = 20;
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while (!(DHT22_GPIO_PORT->IDR & DHT22_GPIO_PIN) && (delay_5us > 0));
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if ((delay_5us > 1) || (delay_5us < 3)) return DHT22_RCV_BAD_ACK1;
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delay_5us = 20;
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while ((DHT22_GPIO_PORT->IDR & DHT22_GPIO_PIN) && (delay_5us > 0));
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if ((wait > 1) || (wait < 3)) return DHT22_RCV_BAD_ACK2;
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// ACK strobe received --> receive 40 bits
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i = 0;
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while (i < 40) {
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// Measure bit start impulse (T_low = 50us)
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delay_5us = 4;
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while (!(DHT22_GPIO_PORT->IDR & DHT22_GPIO_PIN) && (delay_5us > 0));
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if (delay_5us <= 3) {
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// invalid bit start impulse length
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bits[i] = 0xffff;
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delay_5us = 4;
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while ((DHT22_GPIO_PORT->IDR & DHT22_GPIO_PIN) && (delay_5us > 0));
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} else {
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// Measure bit impulse length (T_h0 = 25us, T_h1 = 70us)
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delay_5us = 4;
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while ((DHT22_GPIO_PORT->IDR & DHT22_GPIO_PIN) && (delay_5us > 0));
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bits[i] = (delay_5us <= 3) ? delay_5us * 5 : 0xffff;
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}
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i++;
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}
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DallasDeConfigTimer();
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for (i = 0; i < 40; i++) if (bits[i] == 0xffff) return DHT22_RCV_RCV_TIMEOUT;
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return DHT22_RCV_OK;
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}
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uint16_t DHT22_DecodeReadings(void) {
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uint8_t parity;
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uint8_t i = 0;
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hMSB = 0;
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for (; i < 8; i++) {
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hMSB <<= 1;
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if (bits[i] > 7) hMSB |= 1;
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}
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hLSB = 0;
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for (; i < 16; i++) {
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hLSB <<= 1;
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if (bits[i] > 7) hLSB |= 1;
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}
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tMSB = 0;
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for (; i < 24; i++) {
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tMSB <<= 1;
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if (bits[i] > 7) tMSB |= 1;
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}
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tLSB = 0;
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for (; i < 32; i++) {
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tLSB <<= 1;
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if (bits[i] > 7) tLSB |= 1;
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}
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for (; i < 40; i++) {
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parity_rcv <<= 1;
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if (bits[i] > 7) parity_rcv |= 1;
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}
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parity = hMSB + hLSB + tMSB + tLSB;
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return (parity_rcv << 8) | parity;
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}
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uint16_t DHT22_GetHumidity(void) {
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return (hMSB << 8) + hLSB;
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}
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uint16_t DHT22_GetTemperature(void) {
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return (tMSB << 8) + tLSB;
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}
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