implicit deceleration and unknown type errors [closed]

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Closed 9 years ago.

I am trying to convert some C code that is used for an Arduino microcontroller to be used with a Raspberry Pi microcontroller. They both use different libraries and it may be the problem I am having but am unsure hopefully I just have a couple small errors I'm not seeing I've been trying to solve this for a while now. I am getting the following errors:

temp.c: In function âloopâ:
temp.c:29:5: error: implicit declaration of function âgetGyroValuesâ [-Werror=implicit-function-declaration]
temp.c: At top level:
temp.c:37:6: error: conflicting types for âgetGyroValuesâ [-Werror]
temp.c:29:5: note: previous implicit declaration of âgetGyroValuesâ was here
temp.c: In function âgetGyroValuesâ:
temp.c:38:5: error: unknown type name âbyteâ
cc1: all warnings being treated as errors

Here is my code that I have written:

#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdint.h>
#include <time.h>
#include <wiringPi.h>
#include <wiringPiI2C.h>

#define CTRL_REG1 0x20
#define CTRL_REG2 0x21
#define CTRL_REG3 0x22
#define CTRL_REG4 0x23


int fd,x,y,z;

void setup(){
    fd = wiringPiI2CSetup(0x69); // I2C address of gyro
    wiringPiI2CWriteReg8(fd, CTRL_REG1, 0x1F); //Turn on all axes, disable power down
    wiringPiI2CWriteReg8(fd, CTRL_REG3, 0x08); //Enable control ready signal
    wiringPiI2CWriteReg8(fd, CTRL_REG4, 0x80); // Set scale (500 deg/sec)
    delay(100);                                    // Wait to synchronize
}

void loop(){
    getGyroValues();
    // In following Divinding by 114 reduces noise
    printf("Value of X is: %d\n", x / 114);
    printf("Value of Y is: %d\n", y / 114);
    printf("Value of Z is: %d\n", z / 114);
    delay(500);
}

void getGyroValues (){
    byte MSB, LSB;

    LSB = wiringPiI2CReadReg16(fd, 0x28);
    MSB = wiringPiI2CReadReg16(fd, 0x29);
    x = ((MSB << 8) | LSB);

    MSB = wiringPiI2CReadReg16(fd, 0x2B);
    LSB = wiringPiI2CReadReg16(fd, 0x2A);
    y = ((MSB << 8) | LSB);

    MSB = wiringPiI2CReadReg16(fd, 0x2D);
    LSB = wiringPiI2CReadReg16(fd, 0x2C);
    z = ((MSB << 8) | LSB);
}

This is the code I am converting:

#include <Wire.h>

#define CTRL_REG1 0x20
#define CTRL_REG2 0x21
#define CTRL_REG3 0x22
#define CTRL_REG4 0x23

int Addr = 105;                 // I2C address of gyro
int x, y, z;

void setup(){
  Wire.begin();
  Serial.begin(9600);
  writeI2C(CTRL_REG1, 0x1F);    // Turn on all axes, disable power down
  writeI2C(CTRL_REG3, 0x08);    // Enable control ready signal
  writeI2C(CTRL_REG4, 0x80);    // Set scale (500 deg/sec)
  delay(100);                   // Wait to synchronize 
}

void loop(){
  getGyroValues();              // Get new values
  // In following Dividing by 114 reduces noise
  Serial.print("Raw X:");  Serial.print(x / 114);  
  Serial.print(" Raw Y:"); Serial.print(y / 114);
  Serial.print(" Raw Z:"); Serial.println(z / 114);
  delay(500);                   // Short delay between reads
}

void getGyroValues () {
  byte MSB, LSB;

  MSB = readI2C(0x29);
  LSB = readI2C(0x28);
  x = ((MSB << 8) | LSB);

  MSB = readI2C(0x2B);
  LSB = readI2C(0x2A);
  y = ((MSB << 8) | LSB);

  MSB = readI2C(0x2D);
  LSB = readI2C(0x2C);
  z = ((MSB << 8) | LSB);
}

int readI2C (byte regAddr) {
    Wire.beginTransmission(Addr);
    Wire.write(regAddr);                // Register address to read
    Wire.endTransmission();             // Terminate request
    Wire.requestFrom(Addr, 1);          // Read a byte
    while(!Wire.available()) { };       // Wait for receipt
    return(Wire.read());                // Get result
}

void writeI2C (byte regAddr, byte val) {
    Wire.beginTransmission(Addr);
    Wire.write(regAddr);
    Wire.write(val);
    Wire.endTransmission();
}

Answer 1

1.The return type from wiringPiI2CReadReg16() is int. So use int as the datatype for variables MSB and LSB instead of byte.

void getGyroValues (){
    int MSB, LSB;

    LSB = wiringPiI2CReadReg16(fd, 0x28);
    MSB = wiringPiI2CReadReg16(fd, 0x29);
    x = ((MSB << 8) | LSB);

    MSB = wiringPiI2CReadReg16(fd, 0x2B);
    LSB = wiringPiI2CReadReg16(fd, 0x2A);
    y = ((MSB << 8) | LSB);

    MSB = wiringPiI2CReadReg16(fd, 0x2D);
    LSB = wiringPiI2CReadReg16(fd, 0x2C);
    z = ((MSB << 8) | LSB);
}

2.And either move the definition of getGyroValues() before the loop() function or define a prototype for this function before loop().

Answer 2

1. Declare prototypes for the function getGyroValues (and other functions as well) or define them before calling.

2. There's no datatype byte in C. So it's wrong (unless you have typedef'ed something as byte)