Hi, I am new on this forum,
so want to say hello 
I play with arduino about few months
I need your help or advise how to set code for my MS5541C pressure sensor,
data sheet can be find here
I found one code on this forum,
/*
MS5541 Pressure Sensor demonstration sketch
To obtain the calibration factors run the read-calwords-sketch before.
Circuit:
MS5541 sensor attached to pins 10 - 13:
MOSI: pin 11
MISO: pin 12
SCK: pin 13
MCLK: pin 9
CS is not in use, but might be pin 10
Â
created August 2011
by SMStrauch based on application note AN510 from www.intersema.ch (http://www.meas-spec.com/downloads/Using_SPI_Protocol_with_Pressure_Sensor_Modules.pdf),
and with help of robtillaart and ulrichard. Thanks!
*/
// include librariy:
#include <SPI.h>
// generate a MCKL signal
const int clock = 9;
//include the calibration factors according to your individual sensor; they MUST be long for internal calculation of the compensated values
//intersema.ch provides a file with expected values
const long c1 = 2723;
const long c2 = 4648;
const long c3 = 388;
const long c4 = 224;
const long c5 = 2309;
const long c6 = 54;
void resetsensor() //this function keeps the sketch a little shorter
{
 SPI.setDataMode(SPI_MODE0);
 SPI.transfer(0x15);
 SPI.transfer(0x55);
 SPI.transfer(0x40);
}
void setup() {
 Serial.begin(9600);
 SPI.begin();
 SPI.setBitOrder(MSBFIRST);
 SPI.setClockDivider(SPI_CLOCK_DIV32); //divide 16 MHz to communicate on 500 kHz
 pinMode(clock, OUTPUT); //sets clockpin on output
}
void loop()
{
 TCCR1B = (TCCR1B & 0xF8) | 1 ; //generates the MCKL signal
 analogWrite (clock, 128) ;
 void resetsensor(); //resets the sensor, be aware SPI remains in Mode 0 afterwards!
 //Temperature:
 unsigned int tempMSB = 0; //first byte of value
 unsigned int tempLSB = 0; //last byte of value
 unsigned int D2 = 0;
 SPI.transfer(0x0F); //send first byte of command to get temperature value
 SPI.transfer(0x20); //send second byte of command to get temperature value
 delay(35); //wait for conversion end
 SPI.setDataMode(SPI_MODE1); //change mode in order to listen
 tempMSB = SPI.transfer(0x00); //send dummy byte to read first byte of value
 tempMSB = tempMSB << 8; //shift first byte
 tempLSB = SPI.transfer(0x00); //send dummy byte to read second byte of value
 D2 = tempMSB | tempLSB; //combine first and second byte of value
 Serial.print("Temperature raw =");
 Serial.println(D2); //voilá!
 void resetsensor();//resets the sensor
 //Pressure:
 unsigned int presMSB = 0; //first byte of value
 unsigned int presLSB =0; //last byte of value
 unsigned int D1 = 0;
 SPI.transfer(0x0F); //send first byte of command to get pressure value
 SPI.transfer(0x40); //send second byte of command to get pressure value
 delay(35); //wait for conversion end
 SPI.setDataMode(SPI_MODE1); //change mode in order to listen
 presMSB = SPI.transfer(0x00); //send dummy byte to read first byte of value
 presMSB = presMSB << 8; //shift first byte
 presLSB = SPI.transfer(0x00); //send dummy byte to read second byte of value
 D1 = presMSB | presLSB; //combine first and second byte of value
 Serial.print("Pressure raw =");
 Serial.println(D1);
 //calculation of the real values by means of the calibration factors and the maths
 //in the datasheet
 const long UT1 = (c5 << 3) + 10000;
 const long dT = D2 - UT1;
 const long TEMP = 200 + ((dT * (c6 + 100)) >> 11);
 const long OFF = c2 + (((c4 - 250) * dT) >> 12) + 10000;
 const long SENS = (c1/2) + (((c3 + 200) * dT) >> 13) + 3000;
 long PCOMP = (SENS * (D1 - OFF) >> 12) + 1000;
 float TEMPREAL = TEMP/10;
 //2nd order compensation only for T > 0°C
 const long dT2 = dT - ((dT >> 7 * dT >> 7) >> 3);
 const float TEMPCOMP = (200 + (dT2*(c6+100) >>11))/10;
 Serial.print("Real Temperature [°C]=");
 Serial.println(TEMPREAL);
 Serial.print("Compensated pressure [mbar] =");
 Serial.println(PCOMP);
 Serial.print("2nd order compensated temperature [°C] =");
 Serial.println(TEMPCOMP);Â
 delay(5000);
}
those two guys who were played with this sensor wrote they made working code for data readings,
they showed values they got from sensor in serial monitor, those readings looked ok,
but I used this code they placed on that topic, and it isn't working well in my case,
don't know what to set up to get good readings,
i have that values in my serial monitor,
"
Temperature raw =29429
Pressure raw =2047
Real Temperature [°C]=27.10
Compensated pressure [mbar] =-12618
2nd order compensated temperature [°C] =27.00
Temperature raw =49151
Pressure raw =2047
Real Temperature [°C]=175.40
Compensated pressure [mbar] =-16794
2nd order compensated temperature [°C] =175.00
"
once temp. is print correct,
second time and any other after with bad readings,
pressure is not correct all the time
I appreciate your help
