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Topic: error: conflicting types for '[methodName]' (Read 1 time) previous topic - next topic


Jun 07, 2006, 08:16 am Last Edit: Jun 07, 2006, 08:17 am by coopy Reason: 1
I am writing software to read and determine peak values from a memsic 2125 accelerometer. In my code I have a convenience method to update sensor reading values, 'void readNew()'. It is the only method by this name.

When I try to compile the program, it refuses and gives me the error:
" error: conflicting types for 'readNew' "

Can anyone tell me why I'm getting this error?

Pasted below is the source code. The troublesome method is at the end of the code. I am using Arduino 0003 on an Apple iBook G4 with OS X Tiger.

EDIT: I removed the method type (void) from both readNew() and saveOld() methods. The source code now compiles fine. If I uncomment the last part of the source code though (the two printout methods), I get an "unexpected token: void" error for the last method. This all sounds like some syntax error earlier in the code, but I can't find anything wrong with it.
/*  _________________________________________
   Reading peak values from an accelerometer

// Hardware
int ledPin = 13;
int xaccPin = 7;
int yaccPin = 6;

// low-level
int count, value;

// Constants
//#define MOTION_THRESHOLD 100; // gives strange errors.

// Variables
int nx, ox;    // new and old x acceleration values

// method to determine if motion above threshold is detected
boolean motionStarted() {
 boolean hasStarted;
 readNew();                        // read new acc. values      
 hasStarted = (nx - ox) > MOTION_THRESHOLD; // TODO: implement y axis
 saveOld();                        // save old acc. values
 return hasStarted;

void loop() {
 // wait until action detected

 // loop until acceleration has ceased
 while(nx > ox) {
   delay(50); // ONLY FOR DEBUG

/* -------------------------------------------------
Low-level stuff

void setup() {
 beginSerial(19200); // Sets the baud rate to 19200
 pinMode(ledPin, OUTPUT);
 pinMode(xaccPin, INPUT);
 pinMode(yaccPin, INPUT);
 // initialize new and old acc. values

// method to convert raw acc. value to acceleration
int operateAcceleration(int time1) {  
 return abs(8 * (time1 / 10 - 500));

// method to read value from accelerometer sensor
int readAcc(int axe) {
 count = 0;
 value = digitalRead(axe);
 while(value == HIGH) { // Loop until pin reads a low
   value = digitalRead(axe);
 while(value == LOW) { // Loop until pin reads a high
   value = digitalRead(axe);
 while(value == HIGH) { // Loop until pin reads a low and count
   value = digitalRead(axe);
   count = count + 1;
 //determine the value
 return operateAcceleration(count * 18); // * 18 calculates the time in miliseconds

// method to update acceleration values
void readNew() {
 nx = readAcc(xaccPin);
 //ny = readAcc(yaccPin);

// method to save old acceleration values
void saveOld() {
 ox = nx;
 //oy = ny;

// method to print an integer to serial port
void printValue(int i) {

// method to print a string to serial port
void printValue(String s) {


It seems that all the problems were there because the Arduino compiler needs a method to be declared at a point in the code before it is used. I thought that it compiled Java-style and not procedurally.  :'(


Arduino 0004 takes care of some of these problems for you (though you'll need to give a return type, e.g. "void" for each function).  Although the C/C++ compiler used internally by Arduino requires functions to be declared before use, Arduino 0004 attempts to automatically insert these declarations for you.

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