119 lines
2.8 KiB
C
119 lines
2.8 KiB
C
#include "main.h"
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#include "generic_macros.h"
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#include "lcd.h"
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#include "DHT11.h"
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extern TIM_HandleTypeDef htim2;
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static inline void wait(uint32_t wait_us)
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{
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uint32_t target_time = TIM2->CNT;
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target_time += wait_us << 4;
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while (TIM2->CNT < target_time) {}
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}
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static inline size_t dht11_measure_high_duration(void)
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{
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SKIP_LOW;
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uint32_t start_time = TIM2->CNT;
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SKIP_HIGH;
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uint32_t end_time = TIM2->CNT;
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// elapsed_time > 49us ? 1 : 0
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return (end_time - start_time) > (49 << 4);
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}
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static size_t dht11_read_value(struct DHT11_Data *data)
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{
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// treat data as a normal array to simplify read loop
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uint8_t *buffer = (uint8_t *) data;
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register uint32_t read_register = 0;
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HAL_TIM_Base_Start(&htim2);
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// try to trigger the output
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for (int t = 0; t < 10; t++) {
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TIM2->CNT = 0;
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GPIOD->MODER |= 0x00400000; // enable output mode on GPIOD 11
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GPIOD->BSRR = GPIO_PIN_11; // enable DHT11
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wait(50000); // hold HIGH for 50 ms
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GPIOD->BSRR = GPIO_PIN_11 << 16; // start signal
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wait(30000); // hold it for 30 ms
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GPIOD->BSRR = GPIO_PIN_11; // pull up, DHT will now take control over the connection
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wait(100);
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GPIOD->MODER &= 0xFF3FFFFF; // switch GPIOD 11 to input mode
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// reading pull down from DHT11
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SKIP_LOW;
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// waiting for response
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for (size_t i = TIM2->CNT + (200000 << 4); TIM2->CNT <= i; )
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if (!(GPIOD->IDR & 0x0800))
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goto reading_data;
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}
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// if didn't exit through goto, then DHT11 awaiting has timed out
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HAL_TIM_Base_Stop(&htim2);
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return 1;
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reading_data:
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// read 5 bytes of data
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for (size_t i = 0; i < 5; i++) {
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for (register size_t j = 0; j < 8; j++) {
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read_register <<= 1;
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read_register |= dht11_measure_high_duration();
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}
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buffer[i] = (uint8_t) read_register;
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}
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HAL_TIM_Base_Stop(&htim2);
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return 0;
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}
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int DHT11_run_test(void)
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{
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DISPLAY_CLEAR;
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display_write_data_seq("DHT11 Temp+Humid");
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struct DHT11_Data data;
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size_t result = dht11_read_value(&data);
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size_t checksum_mismatch = ((
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data.humid_decimal
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+ data.humid_integral
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+ data.temp_decimal
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+ data.temp_integral
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) & 0xFF) != data.crc;
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if (result) {
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DISPLAY_SET_CURSOR(1, 4);
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display_write_data_seq("StartTimeout");
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} else if (checksum_mismatch) {
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DISPLAY_SET_CURSOR(1, 4);
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display_write_data_seq("CRC Fault");
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} else {
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DISPLAY_SET_CURSOR(1, 4);
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display_write_data_seq("OK");
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DISPLAY_SET_CURSOR(1, 7);
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display_write_data_byte('0' + (data.humid_integral/10)%10);
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display_write_data_byte('0' + (data.humid_integral)%10);
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display_write_data_seq("% ");
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display_write_data_byte('0' + (data.temp_integral/10)%10);
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display_write_data_byte('0' + (data.temp_integral)%10);
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display_write_data_byte('.');
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display_write_data_byte('0' + data.temp_decimal);
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display_write_data_seq("C");
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}
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return (result || checksum_mismatch);
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}
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