Getting the ADXL 345 and Datalogger working together

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kjata1013
 
Posts: 21
Joined: Sat Mar 03, 2012 6:50 pm

Getting the ADXL 345 and Datalogger working together

Post by kjata1013 »

Hello,
I'm having trouble getting the ADXL345 Accelerometer and the Datalogging shield from Adafruit working together. I can get them to function separately, but not together. Here is my code ("frankensteined" from Sparkfun and SD library downloaded from Adafruit):

Code: Select all

//Add the SPI library so we can communicate with the ADXL345 sensor
#include <SPI.h>
#include <SD.h>

//Assign the Chip Select signal to pin 10.
int CS=10;

//This is a list of some of the registers available on the ADXL345.
//To learn more about these and the rest of the registers on the ADXL345, read the datasheet!
char POWER_CTL = 0x2D;	//Power Control Register
char DATA_FORMAT = 0x31;
char DATAX0 = 0x32;	//X-Axis Data 0
char DATAX1 = 0x33;	//X-Axis Data 1
char DATAY0 = 0x34;	//Y-Axis Data 0
char DATAY1 = 0x35;	//Y-Axis Data 1
char DATAZ0 = 0x36;	//Z-Axis Data 0
char DATAZ1 = 0x37;	//Z-Axis Data 1

//This buffer will hold values read from the ADXL345 registers.
char values[10];
//These variables will be used to hold the x,y and z axis accelerometer values.
int count,x,y,z;

File myFile;
//const int chipSelect = 10;

void setup(){ 
  
   Serial.begin(115200);
  
  while (!Serial) {
    ; // wait for serial port to connect. Needed for Leonardo only
  }


  Serial.print("Initializing SD card...");
  // On the Ethernet Shield, CS is pin 4. It's set as an output by default.
  // Note that even if it's not used as the CS pin, the hardware SS pin 
  // (10 on most Arduino boards, 53 on the Mega) must be left as an output 
  // or the SD library functions will not work. 
  pinMode(SS, OUTPUT);
   
  if (!SD.begin(CS)) {
    Serial.println("initialization failed!");
    return;
  }
  Serial.println("initialization done.");
  
  myFile = SD.open("test.txt", FILE_WRITE);
  if (myFile)
  {
    Serial.print("Setting up... ");
  myFile.print("Time");
  myFile.print("\t");
  
  myFile.print("x");
  myFile.print("\t");
  
  myFile.print("y");
  myFile.print("\t");
  
  myFile.print("z");
  myFile.print("\n");  
  
  //myFile.close();
  Serial.println("Setup comlete.");
  }
  else
  {
    Serial.println("Error opening file.");
  }
  
  //Initiate an SPI communication instance.
  SPI.begin();
  //Configure the SPI connection for the ADXL345.
  SPI.setDataMode(SPI_MODE3);
  //Create a serial connection to display the data on the terminal.
 
  
  //Set up the Chip Select pin to be an output from the Arduino.
  pinMode(CS, OUTPUT);
  //Before communication starts, the Chip Select pin needs to be set high.
  digitalWrite(CS, HIGH);
  
  //Put the ADXL345 into +/- 4G range by writing the value 0x01 to the DATA_FORMAT register.
  writeRegister(DATA_FORMAT, 0x01);
  //Put the ADXL345 into Measurement Mode by writing 0x08 to the POWER_CTL register.
  writeRegister(POWER_CTL, 0x08);  //Measurement mode  
}

void loop(){
  //Reading 6 bytes of data starting at register DATAX0 will retrieve the x,y and z acceleration values from the ADXL345.
  //The results of the read operation will get stored to the values[] buffer.
  readRegister(DATAX0, 6, values);

  //The ADXL345 gives 10-bit acceleration values, but they are stored as bytes (8-bits). To get the full value, two bytes must be combined for each axis.
  //The X value is stored in values[0] and values[1].
  x = ((int)values[1]<<8)|(int)values[0];
  //The Y value is stored in values[2] and values[3].
  y = ((int)values[3]<<8)|(int)values[2];
  //The Z value is stored in values[4] and values[5].
  z = ((int)values[5]<<8)|(int)values[4];
  
  //Print the results to the terminal.
  if (myFile)
  {
    
  while(count < 61)
  {  
    Serial.println("logging...");
   // myFile = SD.open("test.txt", FILE_WRITE);
    count = count + 1;
    myFile.print(count);
    myFile.print("\t");
    myFile.print(x, DEC);
    myFile.print("\t");
    myFile.print(y, DEC);
    myFile.print("\t");
    myFile.print(z, DEC);
    myFile.print("\n");  
    delay(1000); 
  }
  myFile.close();
  Serial.println("Logging complete.");
  }
}

//This function will write a value to a register on the ADXL345.
//Parameters:
//  char registerAddress - The register to write a value to
//  char value - The value to be written to the specified register.
void writeRegister(char registerAddress, char value){
  //Set Chip Select pin low to signal the beginning of an SPI packet.
  digitalWrite(CS, LOW);
  //Transfer the register address over SPI.
  SPI.transfer(registerAddress);
  //Transfer the desired register value over SPI.
  SPI.transfer(value);
  //Set the Chip Select pin high to signal the end of an SPI packet.
  digitalWrite(CS, HIGH);
}

//This function will read a certain number of registers starting from a specified address and store their values in a buffer.
//Parameters:
//  char registerAddress - The register addresse to start the read sequence from.
//  int numBytes - The number of registers that should be read.
//  char * values - A pointer to a buffer where the results of the operation should be stored.
void readRegister(char registerAddress, int numBytes, char * values){
  //Since we're performing a read operation, the most significant bit of the register address should be set.
  char address = 0x80 | registerAddress;
  //If we're doing a multi-byte read, bit 6 needs to be set as well.
  if(numBytes > 1)address = address | 0x40;
  
  //Set the Chip select pin low to start an SPI packet.
  digitalWrite(CS, LOW);
  //Transfer the starting register address that needs to be read.
  SPI.transfer(address);
  //Continue to read registers until we've read the number specified, storing the results to the input buffer.
  for(int i=0; i<numBytes; i++){
    values[i] = SPI.transfer(0x00);
  }
  //Set the Chips Select pin high to end the SPI packet.
  digitalWrite(CS, HIGH);
}
As always, any help would be awesome. I think it has to do with the chip select, both the adxl and the shield want to use it with pin 10. The sparkfun code uses "CS" and the SD example use chipSelect. I've commented one out as you can see and have tried moving things around but no luck. Thanks for looking! Sorry my code is a mess.

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adafruit_support_bill
 
Posts: 88092
Joined: Sat Feb 07, 2009 10:11 am

Re: Getting the ADXL 345 and Datalogger working together

Post by adafruit_support_bill »

I think it has to do with the chip select, both the adxl and the shield want to use it with pin 10
This is not possible. You need to assign them different chip select pins. If you have them both connected to the same pin, they will both be active on the bus at the same time.

kjata1013
 
Posts: 21
Joined: Sat Mar 03, 2012 6:50 pm

Re: Getting the ADXL 345 and Datalogger working together

Post by kjata1013 »

Ok. Can chip select be any digital pin? Or is it like SCL and SDA where only certain pins can do it?

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adafruit_support_bill
 
Posts: 88092
Joined: Sat Feb 07, 2009 10:11 am

Re: Getting the ADXL 345 and Datalogger working together

Post by adafruit_support_bill »

In theory, you can use any digital pin. Some libraries are hard-coded for a specific pin.

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