請問 H48C 三軸加速規 arduino的問題

undead1515

如題  
此sensor的datasheet為http://www.parallax.com/Portals/0/Downloads/docs/prod/acc/HitachiH48C3AxisAccelerometer.pdf

有寫了程式碼 基本上都會動 只是在靜止的時候

為什麼Z軸(垂直於sensor的那軸)都一直是大約在0.05G

其他的X Y 軸 都晃動的很小

以下是程式碼:


// Constants:
#define xAxis 0
#define yAxis 1
#define zAxis 2
int Cnt2Mv = (short) 52813;  // 0.80586*65536
int GfCnv = 14418;  //0.22*65536
//  Pins:
#define clkPin 8
#define dioPin 9
#define csPin 10

void setup()
{
Serial.begin( 9600 );

pinMode( dioPin, OUTPUT );
pinMode( clkPin, OUTPUT );
pinMode( csPin,  OUTPUT );

digitalWrite( csPin, HIGH );  // disable device
digitalWrite( clkPin, LOW );
digitalWrite( dioPin, LOW );
}

void loop()
{
int a;
int value = 0;
// a =readValue( 3 );
//3 is reference voltage
value = gForce( xAxis );
Serial.print( "x = " );
Serial.print( value );

//a =readValue( 3 );
value = gForce( yAxis );
Serial.print( "\ty = " );
Serial.print( value );

//a =readValue( 3 );
value = gForce( zAxis );
Serial.print( "\tz = " );
Serial.println( value );

delay( 200 );  // wait 1sec
}

int gForce( int adcValue, int refValue )
{
if( adcValue >= refValue )
   return umulf( adcValue - refValue, GfCnv );
else
   return -umulf( refValue - adcValue, GfCnv );
}

int gForce( int axis )
{
int refValue = readValue( 3 );
//Serial.println(refValue);
//delay( 1 );  // wait 1msec
int adcValue = readValue( axis );
//Serial.println(adcValue);
return gForce( adcValue, refValue );
}

int readValue( int channel )
{
int data = 0;
int sig = ( ( 0x0018 + channel ) << 11 );
digitalWrite(csPin, LOW);

myShiftOut(dioPin, clkPin, 5, 1, sig );

//delayMicroseconds( 200 );
data = myShiftIn( dioPin, clkPin, 13 );

digitalWrite( csPin, HIGH );

//Serial.println(data);

return data;
}

void myShiftOut(int dataPin, int clockPin, int bitCount, int bitOrder, int val ) {

pinMode( dataPin, OUTPUT );

for( int i = 0; i < bitCount; i++) {



   if (bitOrder < 0) {   // if shiftout from LSB
     digitalWrite( dataPin, ( val & 1) );
     delayMicroseconds( 50 );
     digitalWrite( clockPin, HIGH );
     val = val >> 1;
   }
   else {                // else shiftout from MSB
     digitalWrite( dataPin, ((val >> 15)&1) );
     delayMicroseconds( 50 );
     digitalWrite( clockPin, HIGH );
     val = val << 1;
   }

   digitalWrite( clockPin, LOW );
}
}

int myShiftIn(int dataPin, int clockPin, int bitCount) {
int pinState = 0;
int dataIn = 0;
pinMode( clockPin, OUTPUT );
pinMode( dataPin, INPUT );

for(int i = 0; i < bitCount; i++) {
    int temp = -1;
    digitalWrite(clockPin, HIGH) ;
    //delayMicroseconds( 20 );
    temp = digitalRead( dataPin );

    if (temp > 0){

pinState = 1;

}
    else if(temp == 0){

pinState = 0;

}

dataIn = (dataIn << 1) | pinState;
    digitalWrite(clockPin, LOW);
}
//Serial.println(dataIn);
dataIn = dataIn & 0x0fff;
//Serial.println(dataIn);
  return dataIn;
}

int umulf( int readvalue, int fraction )
{
int result = 0;
int rest = 0;
int temp, temp2;

for ( int i = 1; i < 17; i ++ )
{
   if ( fraction < 0 ) //b15 set
   {
     result += ( ( readvalue >> i ) & 0x7FFF );             //accumulate integer result
     temp = ( ( readvalue & ( ( 1 << i ) - 1) ) << ( 16 - i ) ); //accumulate rest R/65536
     temp2 = rest ^ temp; // never overflow if sign(rest) != sign(temp)
     rest += temp; //accumulate rest R/65536
     //if (CPU.carry()) result++;                  //update result if rest overflows
     if ( temp2 >= 0 ) //b15 clear, signs equal -> test for overflow
     {
       if ( ( rest ^ temp ) < 0) result ++; //new rest has different sign than temp
     }
   }
   fraction <<= 1; //next bit
}
if ( rest < 0 ) result ++; //roundoff
return result;
}



還請各位神手幫忙

Curtiss

Z軸不是應該有  1g 的地球重力加速度？

g921002

在datasheet第4頁有ADC的讀值(From MCP3204)，看看讀出來的值是不是跟datasheet上面的差不多？
如果不是的話，可能要檢查SPI的讀寫邊緣設定(上緣抓值還是下緣抓值？)是不是正確。

undead1515

是阿  不過他一直呈現著 大概是 0.05g

還請各位大大幫忙

g921002

那你三軸的ADC讀值是多少?

undead1515

X Y 都大概是 1  2 3 單位是 0.001G

只有Z 比較怪一點