porting bmp280 driver for Beaglebone Black

main.c

/* This work is licensed under a Creative Commons CCZero 1.0 Universal License.
 * See http://creativecommons.org/publicdomain/zero/1.0/ for more information. */


#include <stdio.h>
#include <stdlib.h>

#include <unistd.h>
#include <linux/i2c-dev.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>

#include "bmp280.h"

#define	I2C_BUFFER_LEN 8
#define BUFFER_LENGTH	0xFF
#define BMP280_DATA_INDEX	1
#define BMP280_ADDRESS_INDEX	2

// delay routine
void BMP280_dela_msek(u32 msek){
	// do nothing
}

s8  myBMP280_I2C_bus_write(u8 dev_addr, u8 reg_addr, u8 *reg_data, u8 cnt)
{
	s32 iError = BMP280_INIT_VALUE;
	u8 array[I2C_BUFFER_LEN];
	u8 stringpos = BMP280_INIT_VALUE;
	array[BMP280_INIT_VALUE] = reg_addr;

	/*
	 * Please take the below function as your reference for
	 * write the data using I2C communication
	 * "IERROR = I2C_WRITE_STRING(DEV_ADDR, ARRAY, CNT+1)"
	 * add your I2C write function here
	 * iError is an return value of I2C read function
	 * Please select your valid return value
	 * In the driver SUCCESS defined as BMP280_INIT_VALUE
	 * and FAILURE defined as -1
	 * Note :
	 * This is a full duplex operation,
	 * The first read data is discarded, for that extra write operation
	 * have to be initiated.Thus cnt+1 operation done in the I2C write string function
	 * For more information please refer data sheet SPI communication:
	 */

	// ---- Opening the Bus ---- //
	int file;
	char *filename = "/dev/i2c-2";
	if( ( file = open(filename, O_RDWR) ) < 0 ) { // open() will won't let file buffer works
		perror("Failed to open the i2c bus");
		iError = ERROR;
		return (s8)iError;
	}

	// Initiating communication with I2C device
	int addr = dev_addr;
	// Spezifizieren der Slave-Adresse -> Kommunikation frei geben
	if( ioctl(file, I2C_SLAVE, addr) < 0 ){
		printf("Failed to acquire bus access and/or talk to slave.\n");
		iError = ERROR;
		return (s8)iError;
	}


	// get values into local array
	for (stringpos = BMP280_INIT_VALUE; stringpos < cnt; stringpos++) {
		array[stringpos + BMP280_DATA_INDEX] = *(reg_data + stringpos);
//		printf("W: 0x%02x => 0x%02x\n", stringpos, *(reg_data + stringpos));
	}

	// do the actual register write
	if(write(file, array, cnt+1) != cnt+1){
		printf("Failed to position the read pointer");
		printf("\n\n");
		iError = ERROR;
		return (s8)iError;
	}

	close(file);

	return (s8)iError;
}

s8  myBMP280_I2C_bus_read(u8 dev_addr, u8 reg_addr, u8 *reg_data, u8 cnt)
{
	s32 iError = BMP280_INIT_VALUE;
	u8 array[I2C_BUFFER_LEN] = {BMP280_INIT_VALUE};
	u8 stringpos = BMP280_INIT_VALUE;
	array[BMP280_INIT_VALUE] = reg_addr;

	int file;
	char *filename = "/dev/i2c-2";
	if( ( file = open(filename, O_RDWR) ) < 0 ) { // open() will won't let file buffer works
		perror("Failed to open the i2c bus");
		iError = ERROR;
		return (s8)iError;
	}

	// Initiating communication with I2C device
	int addr = dev_addr;
	// Spezifizieren der Slave-Adresse -> Kommunikation frei geben
	if( ioctl(file, I2C_SLAVE, addr) < 0 ){
		printf("Failed to acquire bus access and/or talk to slave.\n");
		iError = ERROR;
		return (s8)iError;
	}

	// position the register pointer firstly to the start position
	if(write(file, array, 1) != 1){
		printf("Failed to position the read pointer");
		printf("\n\n");
		iError = ERROR;
		return (s8)iError;
	}

	// Using I2C Read
	if(read(file, array,cnt) != cnt){
		printf("Failed to read from the i2c bus.\n");
		printf("\n\n");
		iError = ERROR;
		return (s8)iError;
	}
	close(file);
	/* Please take the below function as your reference
	 * to read the data using I2C communication
	 * add your I2C read function here.
	 * "IERROR = I2C_WRITE_READ_STRING(DEV_ADDR, ARRAY, ARRAY, 1, CNT)"
	 * iError is an return value of SPI write function
	 * Please select your valid return value
	 * In the driver SUCCESS defined as BMP280_INIT_VALUE
	 * and FAILURE defined as -1
	 */

	for (stringpos = BMP280_INIT_VALUE; stringpos < cnt; stringpos++) {
		*(reg_data + stringpos) = array[stringpos];
//		printf("R: 0x%02x => 0x%02x\n", stringpos+reg_addr,  array[stringpos]);
	;
	}
	return (s8)iError;
}

int main(int argc, char** argv) {

	struct bmp280_t bmp280;
	bmp280.bus_read = myBMP280_I2C_bus_read;
	bmp280.bus_write= myBMP280_I2C_bus_write;
	bmp280.dev_addr = BMP280_I2C_ADDRESS1;
	bmp280.delay_msec = BMP280_dela_msek;


	/* The variable used to assign the standby time*/
	u8 v_standby_time_u8 = BMP280_INIT_VALUE;

	/* The variable used to read real temperature*/
	s32 v_actual_temp_combined_s32 = BMP280_INIT_VALUE;
	/* The variable used to read real pressure*/
	u32 v_actual_press_combined_u32 = BMP280_INIT_VALUE;

	/* result of communication results*/
	s32 com_rslt = ERROR;

	com_rslt = bmp280_init(&bmp280);
	com_rslt += bmp280_set_power_mode(BMP280_NORMAL_MODE);
	com_rslt += bmp280_set_work_mode(BMP280_ULTRA_HIGH_RESOLUTION_MODE);
	com_rslt += bmp280_set_standby_durn(BMP280_STANDBY_TIME_1_MS);
	com_rslt += bmp280_get_standby_durn(&v_standby_time_u8);

	/************************* END INITIALIZATION *************************/

	/*------------------------------------------------------------------*
	 ****** INDIVIDUAL APIs TO READ UNCOMPENSATED PRESSURE AND TEMPERATURE*******
	 *---------------------------------------------------------------------*/
	/* API is used to read the uncompensated temperature*/

	while(1){

		com_rslt += bmp280_read_pressure_temperature(&v_actual_press_combined_u32,
		&v_actual_temp_combined_s32);

		printf("temp: %.2f Cel., Pres: %d Pa\n",
				((float)v_actual_temp_combined_s32)/100,
				v_actual_press_combined_u32);
		sleep(1);
	}
	return 0;
}