Raspberry pi sensor hat temperature and pressure logger

LPS22HB.c

/*
To autostart
crontab -e 
* *     * * *   cd "/wherever you put the file/" && ./FILE_NAME


*/
#include "LPS22HB.h"
#include <bcm2835.h>
#include <math.h>
#include <stdio.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>

char I2C_readByte(char reg) {
	char buf[] = {reg};
	bcm2835_i2c_read_register_rs(buf, buf, 1);
	return buf[0];
}
unsigned short I2C_readU16(char reg) {
	char buf[] = {reg, 0};
	bcm2835_i2c_read_register_rs(buf, buf, 2);
	int value = buf[1] * 0x100 + buf[0];
	return value;
}
void I2C_writeByte(char reg, char val) {
	char buf[] = {reg, val};
	bcm2835_i2c_write(buf, 2);
}
void LPS22HB_RESET() {
	uint8_t Buf;
	Buf = I2C_readU16(LPS_CTRL_REG2);
	Buf |= 0x04;
	I2C_writeByte(LPS_CTRL_REG2, Buf); //SWRESET Set 1
	while (Buf) {
		Buf = I2C_readU16(LPS_CTRL_REG2);
		Buf &= 0x04;
	}
}
void LPS22HB_START_ONESHOT() {
	uint8_t Buf;
	Buf = I2C_readU16(LPS_CTRL_REG2);
	Buf |= 0x01; //ONE_SHOT Set 1
	I2C_writeByte(LPS_CTRL_REG2, Buf);
}

uint8_t LPS22HB_INIT() {
    printf("Please run this as root, else the internal lib will crash NOW!\n");
	bcm2835_i2c_begin();
	bcm2835_i2c_setSlaveAddress(LPS22HB_I2C_ADDRESS); //切记不能把I2C关掉
	bcm2835_i2c_set_baudrate(10000);
	if (I2C_readByte(LPS_WHO_AM_I) != LPS_ID)
		return 0;                   //Check device ID
	LPS22HB_RESET();                    //Wait for reset to complete
	I2C_writeByte(LPS_CTRL_REG1, 0x02); //Low-pass filter disabled , output registers not updated until MSB and LSB have been read , Enable Block Data Update , Set Output Data Rate to 0
	return 1;
}

struct _IO_FILE* makeFile() {
	time_t     curr_time;
	struct tm* curr_tm;
	char       dateTime[100];

	time(&curr_time);
	curr_tm = localtime(&curr_time);

	struct stat st = {0};
	if (stat("logs", &st) == -1) {
		mkdir("logs", 0700);
	}

	strftime(dateTime, 50, "logs/%Y-%m-%d_%H:%M:%S.csv", curr_tm);

	printf("We will print into %s\n", dateTime);

	struct _IO_FILE* file = fopen(dateTime, "w+");
	if (file == 0) {
		printf("sadNoise.wav Impossible to open file %s", dateTime);
		exit(1);
	}
	return file;
}

/**
 * Bla bla bla this will check the program is not already running using a classical technique
 */
void fLockCheck() {
	// check if there is another instance running...
	int fd = open("logger.lock", O_CREAT | O_RDWR, 0666);
	if (fd == -1) {
		printf("impossible to open logger.lock");
		exit(1);
	}

	if (flock(fd, LOCK_EX | LOCK_NB) == -1) {
		printf("logger.lock is already locked, I refuse to start.\n (The application is already running.)\n");
		exit(1);
	}
}

int main(int argc, char** argv) {
	fLockCheck();
	struct _IO_FILE* logFile = makeFile();

	int delay = 30;
	if (argc == 1) {
	} else {
		delay = atoi(argv[1]);
	}
	printf("this will run with a delay of %i s \n", delay);

	float   PRESS_DATA = 0;
	float   TEMP_DATA  = 0;
	uint8_t u8Buf[3];
	if (!bcm2835_init())
		return 1;
	printf("\nPressure Sensor Test Program ...\n");
	if (!LPS22HB_INIT()) {
		printf("\nPressure Sensor Error\n");
		return 0;
	}
	printf("\nPressure Sensor OK\n");

	//because the first read is usually 0, we just skip it
	LPS22HB_START_ONESHOT();                       //Trigger one shot data acquisition
	if ((I2C_readByte(LPS_STATUS) & 0x01) == 0x01) //a new pressure data is generated
	{
		u8Buf[0]   = I2C_readByte(LPS_PRESS_OUT_XL);
		u8Buf[1]   = I2C_readByte(LPS_PRESS_OUT_L);
		u8Buf[2]   = I2C_readByte(LPS_PRESS_OUT_H);
		PRESS_DATA = (float)((u8Buf[2] << 16) + (u8Buf[1] << 8) + u8Buf[0]) / 4096.0f;
	}
	if ((I2C_readByte(LPS_STATUS) & 0x02) == 0x02) // a new pressure data is generated
	{
		u8Buf[0]  = I2C_readByte(LPS_TEMP_OUT_L);
		u8Buf[1]  = I2C_readByte(LPS_TEMP_OUT_H);
		TEMP_DATA = (float)((u8Buf[1] << 8) + u8Buf[0]) / 100.0f;
	}
	//should be well enought for he sensor to start working
	sleep(1);

	printf("unixTs,DateTime,Pressure hPa,Temperature °c\n");
	while (1) {
		LPS22HB_START_ONESHOT();                       //Trigger one shot data acquisition
		if ((I2C_readByte(LPS_STATUS) & 0x01) == 0x01) //a new pressure data is generated
		{
			u8Buf[0]   = I2C_readByte(LPS_PRESS_OUT_XL);
			u8Buf[1]   = I2C_readByte(LPS_PRESS_OUT_L);
			u8Buf[2]   = I2C_readByte(LPS_PRESS_OUT_H);
			PRESS_DATA = (float)((u8Buf[2] << 16) + (u8Buf[1] << 8) + u8Buf[0]) / 4096.0f;
		}
		if ((I2C_readByte(LPS_STATUS) & 0x02) == 0x02) // a new pressure data is generated
		{
			u8Buf[0]  = I2C_readByte(LPS_TEMP_OUT_L);
			u8Buf[1]  = I2C_readByte(LPS_TEMP_OUT_H);
			TEMP_DATA = (float)((u8Buf[1] << 8) + u8Buf[0]) / 100.0f;
		}

		char buffer[256];
		//this will give plain unix ts
		time_t t = time(NULL);
		//this will convert the unix ts in a struct with the human format
		struct tm tm = *localtime(&t);

		sprintf(buffer, "%u,%d-%02d-%02d %02d:%02d:%02d,%7.2f,%6.2f\n", (unsigned)time(NULL), tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec, PRESS_DATA, TEMP_DATA);

		printf("%s", buffer);
		fputs(buffer, logFile);
		fflush(logFile);
		sleep(delay);
	}
	return 0;
}