[DHT11] add testing code, currently not functional

Core/Inc/DHT11.h

@@ -0,0 +1,17 @@
+#ifndef __DHT11
+#define __DHT11
+
+#define SKIP_LOW while (!(GPIOD->IDR & 0x0800)) {}
+#define SKIP_HIGH while (GPIOD->IDR & 0x0800) {}
+
+struct DHT11_Data {
+	uint8_t humid_integral;
+	uint8_t humid_decimal;
+	uint8_t temp_integral;
+	uint8_t temp_decimal;
+	uint8_t crc;
+};
+
+void DHT11_run_test(void);
+
+#endif

Core/Src/DHT11.c

@@ -0,0 +1,90 @@
+#include "main.h"
+#include "generic_macros.h"
+#include "lcd.h"
+#include "DHT11.h"
+
+extern TIM_HandleTypeDef htim2;
+
+static void wait(uint32_t wait_us)
+{
+	uint32_t target_time = TIM2->CNT;
+	target_time += wait_us << 4;
+
+	while (TIM2->CNT < target_time) {}
+}
+
+static size_t dht11_measure_high_duration(void)
+{
+	uint32_t start_time = TIM2->CNT;
+	SKIP_HIGH;
+	uint32_t end_time = TIM2->CNT;
+
+	// elapsed_time > 49us ? 1 : 0
+	return (end_time - start_time) > (49 << 4);
+}
+
+static size_t dht11_read_value(struct DHT11_Data *data)
+{
+	// treat data as a normal array to simplify read loop
+	uint8_t *buffer = (uint8_t *) data;
+
+	register uint8_t read_register = 0;
+
+	TIM2->CNT = 0;
+	HAL_TIM_Base_Start(&htim2);
+
+	GPIOD->MODER |= 0x00400000;      // enable output mode on GPIOD 11
+
+	GPIOD->BSRR = GPIO_PIN_11;       // enable DHT11
+	wait(18000);                     // hold HIGH for 18 ms
+	GPIOD->BSRR = GPIO_PIN_11 << 16; // start signal
+	wait(20);                        // hold it for 20 us
+	GPIOD->BSRR = GPIO_PIN_11;       // pull up, DHT will now take control over the connection
+	wait(40);
+
+	GPIOD->MODER &= 0xFF3FFFFF;      // switch GPIOD 11 to input mode
+
+	// reading transmission from DHT11
+	SKIP_LOW;
+
+	// waiting for 50 ms max
+	for (size_t i = TIM2->CNT + (50000 << 4); TIM2->CNT >= i; )
+		if (!(GPIOD->IDR & 0x0800))
+			goto reading_data;
+
+	// if didn't exit through goto, then DHT11 awaiting has timed out
+	return 1;
+
+reading_data:
+	// read 5 bytes of data
+	for (size_t i = 0; i < 5; i++) {
+		for (register size_t j = 0; j < 8; j++) {
+			read_register <<= 1;
+			SKIP_LOW;
+			read_register |= dht11_measure_high_duration();
+		}
+
+		buffer[i] = read_register;
+	}
+
+	HAL_TIM_Base_Stop(&htim2);
+
+	return 0;
+}
+
+void DHT11_run_test(void)
+{
+	DISPLAY_CLEAR;
+	display_write_data_seq("DHT11 Temp+Humid");
+
+	struct DHT11_Data data;
+	size_t result = dht11_read_value(&data);
+
+	if (result == 1) {
+		DISPLAY_SET_CURSOR(1, 1);
+		display_write_data_seq("START TIMEOUT");
+	} else {
+		DISPLAY_SET_CURSOR(1, 1);
+		display_write_data_seq("OK");
+	}
+}

Core/Src/main.c

@@ -78,7 +78,8 @@ void ((*executors[])(void)) = {
 		LIS302DL_run_test_dynamic,
 		MP45DT02_run_test,
 		LSM9DS1_test_accel,
-		LSM9DS1_test_magnet
+		LSM9DS1_test_magnet,
+		DHT11_run_test
 };
 
 void ((*cleanup_functions[])(void)) = {
@@ -92,6 +93,7 @@ void ((*cleanup_functions[])(void)) = {
 		NULL,
 		NULL,
 		LSM9DS1_cleanup_accel,
+		NULL,
 		NULL
 };
 
@@ -106,6 +108,7 @@ int delay_between_runs[] = {
 		200,
 		-1,
 		-1,
+		-1,
 		-1
 		};
 
@@ -133,7 +136,7 @@ static void MX_I2S2_Init(void);
 void switch_to_next_test(void)
 {
 	current_executor_id += 1;
-	current_executor_id %= 11;
+	current_executor_id %= 12;
 }
 
 void buttons_switch_to_interrupt(void)