pin address

ori_michael · June 11, 2018, 11:44am

Hi

I'm trying to use a pressure sensor. The manual is said to connect to the A4 A5 pins.
They can not be changed in code.
In the library I found these lines:

#define MS5611_ADDRESS (0x77)

#define MS5611_CMD_ADC_READ (0x00)
#define MS5611_CMD_RESET (0x1E)
#define MS5611_CMD_CONV_D1 (0x40)<--------------------------------
#define MS5611_CMD_CONV_D2 (0x50)<--------------------------------
#define MS5611_CMD_READ_PROM (0xA2)

I gess they are related to the definition of Finns.

I would like to choose other pins, can you explain to me how to do this please?

Thanks!

the full code:
MS5611.h:

/*
MS5611.h - Header file for the MS5611 Barometric Pressure & Temperature Sensor Arduino Library.

Version: 1.0.0
(c) 2014 Korneliusz Jarzebski
www.jarzebski.pl

This program is free software: you can redistribute it and/or modify
it under the terms of the version 3 GNU General Public License as
published by the Free Software Foundation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef MS5611_h
#define MS5611_h

#if ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif

#define MS5611_ADDRESS                (0x77)

#define MS5611_CMD_ADC_READ           (0x00)
#define MS5611_CMD_RESET              (0x1E)
#define MS5611_CMD_CONV_D1            (0x40)
#define MS5611_CMD_CONV_D2            (0x50)
#define MS5611_CMD_READ_PROM          (0xA2)

typedef enum
{
    MS5611_ULTRA_HIGH_RES   = 0x08,
    MS5611_HIGH_RES         = 0x06,
    MS5611_STANDARD         = 0x04,
    MS5611_LOW_POWER        = 0x02,
    MS5611_ULTRA_LOW_POWER  = 0x00
} ms5611_osr_t;

class MS5611
{
    public:

	bool begin(ms5611_osr_t osr = MS5611_HIGH_RES);
	uint32_t readRawTemperature(void);
	uint32_t readRawPressure(void);
	double readTemperature(bool compensation = false);
	int32_t readPressure(bool compensation = false);
	double getAltitude(double pressure, double seaLevelPressure = 101325);
	double getSeaLevel(double pressure, double altitude);
	void setOversampling(ms5611_osr_t osr);
	ms5611_osr_t getOversampling(void);

    private:

	uint16_t fc[6];
	uint8_t ct;
	uint8_t uosr;
	int32_t TEMP2;
	int64_t OFF2, SENS2;

	void reset(void);
	void readPROM(void);

	uint16_t readRegister16(uint8_t reg);
	uint32_t readRegister24(uint8_t reg);
};

#endif

MS5611.cpp:

/*
MS5611.cpp - Class file for the MS5611 Barometric Pressure & Temperature Sensor Arduino Library.

Version: 1.0.0
(c) 2014 Korneliusz Jarzebski
www.jarzebski.pl

This program is free software: you can redistribute it and/or modify
it under the terms of the version 3 GNU General Public License as
published by the Free Software Foundation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#if ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif

#include <Wire.h>
#include <math.h>

#include <MS5611.h>

bool MS5611::begin(ms5611_osr_t osr)
{
    Wire.begin();

    reset();

    setOversampling(osr);

    delay(100);

    readPROM();

    return true;
}

// Set oversampling value
void MS5611::setOversampling(ms5611_osr_t osr)
{
    switch (osr)
    {
	case MS5611_ULTRA_LOW_POWER:
	    ct = 1;
	    break;
	case MS5611_LOW_POWER:
	    ct = 2;
	    break;
	case MS5611_STANDARD:
	    ct = 3;
	    break;
	case MS5611_HIGH_RES:
	    ct = 5;
	    break;
	case MS5611_ULTRA_HIGH_RES:
	    ct = 10;
	    break;
    }

    uosr = osr;
}

// Get oversampling value
ms5611_osr_t MS5611::getOversampling(void)
{
    return (ms5611_osr_t)uosr;
}

void MS5611::reset(void)
{
    Wire.beginTransmission(MS5611_ADDRESS);
	
    Serial.println("write and send to: ");
	Serial.println(MS5611_CMD_RESET);

    #if ARDUINO >= 100
	Wire.write(MS5611_CMD_RESET);
    #else
	
	Wire.send(MS5611_CMD_RESET);
    #endif

    Wire.endTransmission();
}

void MS5611::readPROM(void)
{
    for (uint8_t offset = 0; offset < 6; offset++)
    {
	fc[offset] = readRegister16(MS5611_CMD_READ_PROM + (offset * 2));
    }
}

uint32_t MS5611::readRawTemperature(void)
{
    Wire.beginTransmission(MS5611_ADDRESS);

    #if ARDUINO >= 100
	Wire.write(MS5611_CMD_CONV_D2 + uosr);
    #else
	Wire.send(MS5611_CMD_CONV_D2 + uosr);
    #endif

    Wire.endTransmission();

    delay(ct);

    return readRegister24(MS5611_CMD_ADC_READ);
}

uint32_t MS5611::readRawPressure(void)
{
    Wire.beginTransmission(MS5611_ADDRESS);

    #if ARDUINO >= 100
	Wire.write(MS5611_CMD_CONV_D1 + uosr);
    #else
	Wire.send(MS5611_CMD_CONV_D1 + uosr);
    #endif

    Wire.endTransmission();

    delay(ct);

    return readRegister24(MS5611_CMD_ADC_READ);
}

int32_t MS5611::readPressure(bool compensation)
{
    uint32_t D1 = readRawPressure();

    uint32_t D2 = readRawTemperature();
    int32_t dT = D2 - (uint32_t)fc[4] * 256;

    int64_t OFF = (int64_t)fc[1] * 65536 + (int64_t)fc[3] * dT / 128;
    int64_t SENS = (int64_t)fc[0] * 32768 + (int64_t)fc[2] * dT / 256;

    if (compensation)
    {
	int32_t TEMP = 2000 + ((int64_t) dT * fc[5]) / 8388608;

	OFF2 = 0;
	SENS2 = 0;

	if (TEMP < 2000)
	{
	    OFF2 = 5 * ((TEMP - 2000) * (TEMP - 2000)) / 2;
	    SENS2 = 5 * ((TEMP - 2000) * (TEMP - 2000)) / 4;
	}

	if (TEMP < -1500)
	{
	    OFF2 = OFF2 + 7 * ((TEMP + 1500) * (TEMP + 1500));
	    SENS2 = SENS2 + 11 * ((TEMP + 1500) * (TEMP + 1500)) / 2;
	}

	OFF = OFF - OFF2;
	SENS = SENS - SENS2;
    }

    uint32_t P = (D1 * SENS / 2097152 - OFF) / 32768;

    return P;
}

double MS5611::readTemperature(bool compensation)
{
    uint32_t D2 = readRawTemperature();
    int32_t dT = D2 - (uint32_t)fc[4] * 256;

    int32_t TEMP = 2000 + ((int64_t) dT * fc[5]) / 8388608;

    TEMP2 = 0;

    if (compensation)
    {
	if (TEMP < 2000)
	{
	    TEMP2 = (dT * dT) / (2 << 30);
	}
    }

    TEMP = TEMP - TEMP2;

    return ((double)TEMP/100);
}

// Calculate altitude from Pressure & Sea level pressure
double MS5611::getAltitude(double pressure, double seaLevelPressure)
{
    return (44330.0f * (1.0f - pow((double)pressure / (double)seaLevelPressure, 0.1902949f)));
}

// Calculate sea level from Pressure given on specific altitude
double MS5611::getSeaLevel(double pressure, double altitude)
{
    return ((double)pressure / pow(1.0f - ((double)altitude / 44330.0f), 5.255f));
}

// Read 16-bit from register (oops MSB, LSB)
uint16_t MS5611::readRegister16(uint8_t reg)
{
    uint16_t value;
    Wire.beginTransmission(MS5611_ADDRESS);
    #if ARDUINO >= 100
        Wire.write(reg);
    #else
        Wire.send(reg);
    #endif
    Wire.endTransmission();

    Wire.beginTransmission(MS5611_ADDRESS);
    Wire.requestFrom(MS5611_ADDRESS, 2);
    while(!Wire.available()) {};
    #if ARDUINO >= 100
        uint8_t vha = Wire.read();
        uint8_t vla = Wire.read();
    #else
        uint8_t vha = Wire.receive();
        uint8_t vla = Wire.receive();
    #endif;
    Wire.endTransmission();

    value = vha << 8 | vla;

    return value;
}

// Read 24-bit from register (oops XSB, MSB, LSB)
uint32_t MS5611::readRegister24(uint8_t reg)
{
    uint32_t value;
    Wire.beginTransmission(MS5611_ADDRESS);
    #if ARDUINO >= 100
        Wire.write(reg);
    #else
        Wire.send(reg);
    #endif
    Wire.endTransmission();

    Wire.beginTransmission(MS5611_ADDRESS);
    Wire.requestFrom(MS5611_ADDRESS, 3);
    while(!Wire.available()) {};
    #if ARDUINO >= 100
        uint8_t vxa = Wire.read();
        uint8_t vha = Wire.read();
        uint8_t vla = Wire.read();
    #else
        uint8_t vxa = Wire.receive();
        uint8_t vha = Wire.receive();
        uint8_t vla = Wire.receive();
    #endif;
    Wire.endTransmission();

    value = ((int32_t)vxa << 16) | ((int32_t)vha << 8) | vla;

    return value;
}

Budvar10 · June 11, 2018, 12:25pm

Welcome to the forum!
You want to use different pins on Arduino, right? Which Arduino?
For communication with the sensor is used I2C bus which is on A4, A5 pins on Arduino UNO. Since R3 version, these pins are doubled (marked SDA, SCL on bottom side) next to AREF - leftmost pins on upper header. It is because other types of Arduino can have it on different port, so it is common place for I2C. Position of I2C is given by HW so NO, you cannot use different pins, but sensor can communicate via SPI optionally. SPI bus is on different pins, but you will need to change your sketch.

ori_michael · June 11, 2018, 1:27pm

Hey

thank you very much for the quick answer!

I think I did not understand anything very basic about the i2c, I read about it a little before I ask again ...

Thank you!

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