Hello, I am new to Arduino and this is my first post.
I am working on a project for a class of mine where we are designing an underwater toy that remains at a constant depth using a pressure sensor to control a servo. We want to set it to go to a certain depth, which will be determined base on pressure, and remain at that depth using a servo to control diving wings.
This project is being carried over from a previous semester and they have gotten to the point where they are receiving the output data from the sensor, a MS5541-CM from Measurement Specialties, using SPI code they found here:
MS5541 depth sensor communication - Sensors - Arduino Forum, they pretty much just copied the whole code and added a few details for themselves.
The issue I am experiencing is that the servo will not run with the code they used. It will lock up and start overheating. I am not really sure what I need to do to remedy the issue, but I assume I will probably need to use SPI in some way to control the servo. Any help with SPI would be helpful. Below is the code I received, with the lcd portion removed.
/*
MS5535C Pressure Sensor calwords readout
This program will read your MS5535C or compatible pressure sensor every 5 seconds and show
you the calibration words, the calibration factors,
the raw values and the compensated values of temperature and pressure.
Once you read out the calibration factors you can define them in the header of any sketch
you write for the sensor.
Pins:
MS5535C sensor attached to pins 10 - 13:
DIN (MOSI): pin 11
DOUT (MISO): pin 12
SCLK: pin 13
MCLK: pin 9
Modified February 2012 by spincrisis for the MS5535C.
*/
// include library:
#include <SPI.h>
#include <LiquidCrystal.h>
#include <Servo.h>
// generate a MCKL signal pin
const int clock = 9;
LiquidCrystal lcd(8,6,5,4,3,2); //12,9,5,4,3,2);
Servo myservo;
//position of servo
int pos = 0;
//the present depth of the sensor in meters
int present_depth = 0;
//the density of water in kilograms/(meters^3)
int density = 1.275; //freshwater = 1000, saltwater = 1020-1029, air = 1.275
//gravity in meters/(seconds^2)
int gravity = 9.81;
//the desired depth for trolling in meters, this value should be set by the user
int desired_depth = 10;
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 prints to the serial port window
Serial.begin(9600);
SPI.begin(); //see SPI library details on arduino.cc for details
SPI.setBitOrder(MSBFIRST);
SPI.setClockDivider(SPI_CLOCK_DIV32); //divide 16 MHz to communicate on 500 kHz
pinMode(clock, OUTPUT);
delay(100);
//prints to the lcd, we printed to the lcd to test the accuracy of the sensor
lcd.begin(16,2);
lcd.print("Temp: ");
//the servo is connected to pin A0
//we commented moving the servo due to interference with the pressure measurements
myservo.attach(14);
delay(100);
}
void loop()
{
TCCR1B = (TCCR1B & 0xF8) | 1 ; //generates the MCKL signal
analogWrite (clock, 128) ;
resetsensor();//resets the sensor - caution: afterwards mode = SPI_MODE0!
//Calibration word 1
unsigned int result1 = 0;
unsigned int inbyte1 = 0;
SPI.transfer(0x1D); //send first byte of command to get calibration word 1
SPI.transfer(0x50); //send second byte of command to get calibration word 1
SPI.setDataMode(SPI_MODE1); //change mode in order to listen
result1 = SPI.transfer(0x00); //send dummy byte to read first byte of word
result1 = result1 << 8; //shift returned byte
inbyte1 = SPI.transfer(0x00); //send dummy byte to read second byte of word
result1 = result1 | inbyte1; //combine first and second byte of word
Serial.print("Calibration word 1 =");
Serial.println(result1);
resetsensor();//resets the sensor
//Calibration word 2; see comments on calibration word 1
unsigned int result2 = 0;
byte inbyte2 = 0;
SPI.transfer(0x1D);
SPI.transfer(0x60);
SPI.setDataMode(SPI_MODE1);
result2 = SPI.transfer(0x00);
result2 = result2 <<8;
inbyte2 = SPI.transfer(0x00);
result2 = result2 | inbyte2;
Serial.print("Calibration word 2 =");
Serial.println(result2);
resetsensor();//resets the sensor
//Calibration word 3; see comments on calibration word 1
unsigned int result3 = 0;
byte inbyte3 = 0;
SPI.transfer(0x1D);
SPI.transfer(0x90);
SPI.setDataMode(SPI_MODE1);
result3 = SPI.transfer(0x00);
result3 = result3 <<8;
inbyte3 = SPI.transfer(0x00);
result3 = result3 | inbyte3;
Serial.print("Calibration word 3 =");
Serial.println(result3);
resetsensor();//resets the sensor
//Calibration word 4; see comments on calibration word 1
unsigned int result4 = 0;
byte inbyte4 = 0;
SPI.transfer(0x1D);
SPI.transfer(0xA0);
SPI.setDataMode(SPI_MODE1);
result4 = SPI.transfer(0x00);
result4 = result4 <<8;
inbyte4 = SPI.transfer(0x00);
result4 = result4 | inbyte4;
Serial.print("Calibration word 4 =");
Serial.println(result4);
//now we do some bitshifting to extract the calibration factors
//out of the calibration words; read datasheet AN510 for better understanding
long c1 = result1 >> 3 & 0x1FFF;
long c2 = ((result1 & 0x07) << 10) | ((result2 >> 6) & 0x03FF);
long c3 = (result3 >> 6) & 0x03FF;
long c4 = (result4 >> 7) & 0x07FF;
long c5 = ((result2 & 0x003F) << 6) | (result3 & 0x003F);
long c6 = result4 & 0x007F;
Serial.println(c1);
Serial.println(c2);
Serial.println(c3);
Serial.println(c4);
Serial.println(c5);
Serial.println(c6);
resetsensor();//resets the sensor
//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!
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 MUST be long
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;
//pressure is converted from mbar to Pa, and the present depth of the sensor is calculated in meters
present_depth = (PCOMP * 100) / (density * gravity);// ((Pressure/0.0145037738)*100)/(1000*9.81)
//if the present depth is more than 2 meters above the desired depth, the servo is rotated CW
//if the present depth is less than 2 meters above the desired depth, the servo is rotated CCW
if (present_depth > desired_depth + 2) {
while(present_depth > desired_depth + 2 && pos <= 90) {
pos += 1;
myservo.write(pos);
delay(15);
}
} else if (present_depth < desired_depth - 2) {
while(present_depth < desired_depth - 2 && pos >= 90) {
pos -= 1;
myservo.write(pos);
delay(15);
}
}
//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("2nd order compensated temperature in °C =");
Serial.println(TEMPCOMP);
delay(500);
}