From f24dd4a4d8be303095b5f31feb8eb17b29f3798f Mon Sep 17 00:00:00 2001
From: dooku <mj370@protonmail.com>
Date: Sun, 18 Jul 2021 11:04:08 +0200
Subject: [PATCH] Fixed missing SHT4x files

---
 fw/Core/Inc/sht4x.h | 57 +++++++++++++++++++++++++++++++++++++++++++++
 fw/Core/Src/sht4x.c | 53 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 110 insertions(+)
 create mode 100644 fw/Core/Inc/sht4x.h
 create mode 100644 fw/Core/Src/sht4x.c

diff --git a/fw/Core/Inc/sht4x.h b/fw/Core/Inc/sht4x.h
new file mode 100644
index 0000000..a33e6b2
--- /dev/null
+++ b/fw/Core/Inc/sht4x.h
@@ -0,0 +1,57 @@
+/*
+ * sht4x.h
+ *
+ *  Created on: Jun 8, 2021
+ *      Author: user
+ */
+
+#ifndef INC_SHT4X_H_
+#define INC_SHT4X_H_
+
+#include "stdint.h"
+#include "stm32l0xx_ll_i2c.h"
+#include "stm32l0xx_ll_utils.h"
+#include "i2c.h"
+#include "crc8.h"
+
+/*
+ * Defines & macros
+ */
+
+#define SHT4X_I2C_ADDRESS 0x44
+
+/*
+ * Return values
+ */
+
+#define SHT4X_OK 0
+#define SHT4X_ERROR -1 // generic error
+#define SHT4X_CRC8_ERROR -2 // checksum failed
+
+/*
+ * Data types
+ */
+
+typedef enum {
+	START_MEAS_HIGH_PRECISION = 0xFD,
+	START_MEAS_MEDIUM_PRECISION = 0xF6,
+	START_MEAS_LOW_PRECISION = 0xE0,
+	READ_SERIAL = 0x89,
+	SOFT_RESET = 0x94,
+	HEATER_200_mW_1_s = 0x39,
+	HEATER_200_mW_01_s = 0x32,
+	HEATER_110_mW_1_s = 0x2F,
+	HEATER_110_mW_01_s = 0x24,
+	HEATER_20_mW_1_s = 0x1E,
+	HEATER_20_mW_01_s = 0x15
+} sht4x_cmd_t;
+
+/*
+ * Function prototypes
+ */
+
+int8_t sht4x_send_cmd(sht4x_cmd_t cmd);
+int8_t sht4x_read_data(uint8_t *buffer, int len);
+int8_t sht4x_measure(int *temperature, int *relative_humidity);
+
+#endif /* INC_SHT4X_H_ */
diff --git a/fw/Core/Src/sht4x.c b/fw/Core/Src/sht4x.c
new file mode 100644
index 0000000..31923f9
--- /dev/null
+++ b/fw/Core/Src/sht4x.c
@@ -0,0 +1,53 @@
+/*
+ * sht4x.c
+ *
+ *  Created on: Jun 8, 2021
+ *      Author: user
+ */
+
+#include "sht4x.h"
+
+int8_t sht4x_send_cmd(sht4x_cmd_t cmd)
+{
+
+}
+
+int8_t sht4x_read_data(uint8_t *buffer, int len)
+{
+
+}
+
+int8_t sht4x_measure(int *temperature, int *relative_humidity)
+{
+	uint8_t buffer[32];
+	int result;
+
+	// start measurement
+	buffer[0] = START_MEAS_HIGH_PRECISION;
+	result = i2c_transmit(SHT4X_I2C_ADDRESS<<1, buffer, 1);
+	if (result != I2C_OK) {
+		return SHT4X_ERROR;
+	}
+	LL_mDelay(100); // 10 ms should be enough
+	// read out
+	result = i2c_receive(SHT4X_I2C_ADDRESS<<1, buffer, 6);
+	if (result != I2C_OK) {
+		return SHT4X_ERROR;
+	}
+	// TODO checksum
+	// Convert to T and RH; taken directly from pseudocode in SHT4x datasheet, page 3
+	uint32_t t_ticks = (buffer[0] << 8) + buffer[1];
+	uint32_t rh_ticks = (buffer[3] << 8) + buffer[4];
+	int t_degC = -45 + 175 * t_ticks / 65535;
+	int rh_pRH = -6 + 125 * rh_ticks / 65535;
+	if (rh_pRH > 100) {
+			rh_pRH = 100;
+	}
+	if (rh_pRH < 0) {
+		rh_pRH = 0;
+	}
+	*temperature = t_degC;
+	*relative_humidity = rh_pRH;
+
+	return SHT4X_OK;
+}