Hello, i'm new to this forum so please be gentle
I've been playing with some optical quadrature encoders and I've observed some unusual behavior which has left me a little confused. The Story so far
I'm using a optical quadrature encoder with 600P/R Incremental Rotary Encoder AB 2 phase 6mm Shaft 5V-24V 12V, i got the encoder from china so no data sheet, it did have this printed on it though
TYPE LPD3806-600BM-85-24C.
This is the circuit i've been using
the one difference is that i havn't attached that large black wire (which is attached to the sheath around the other wires)
Using this code
// code start
# include "digitalWriteFast.h" //
const byte pin_A = 2; // connect white wire here
const byte pin_B = 3; // connect green wire here
int A_set = 0;
int B_set = 0;
long pulses = 0;
void setup()
{
pinMode(pin_A, INPUT);
digitalWrite(pin_A, HIGH); // enables pull-up resistor
pinMode(pin_B, INPUT);
digitalWrite(pin_B, HIGH); // enables pull-up resistor
A_set = digitalRead(pin_A);
B_set = digitalRead(pin_B);
attachInterrupt(0, encoderPinChange_A, CHANGE); // pin 2
attachInterrupt(1, encoderPinChange_B, CHANGE); // pin 3
Serial.begin(9600);
}
void loop()
{
Serial.println(pulses);
}
void encoderPinChange_A()
{
A_set = digitalReadFast2(pin_A) == HIGH;
pulses += (A_set != B_set) ? +1 : -1;
}
void encoderPinChange_B()
{
B_set = digitalReadFast2(pin_B) == HIGH;
pulses += (A_set == B_set) ? +1 : -1;
}
Reading from the serial port i'm able to see the position value (pulses) increase and decrease as i turn the encoder shaft however something isn't quite right. The position value doesn't increment consistently, also sometimes when i move the shaft quickly over a small angle the position value doesn't change at all. I did these tests both by hand (hard to be accurate i know) and using a stepper motor linked to the encoder with a timing belt.
After this i tried the following code
volatile long enc_count = 0;
void setup() {
// all your normal setup code
attachInterrupt(0,encoder_isr,CHANGE);
attachInterrupt(1,encoder_isr,CHANGE);
}
void loop()
{
Serial.println(enc_count);
}
void encoder_isr() {
static int8_t lookup_table[] = {0,-1,1,0,1,0,0,-1,-1,0,0,1,0,1,-1,0};
static uint8_t enc_val = 0;
enc_val = enc_val << 2;
enc_val = enc_val | ((PIND & 0b1100) >> 2)
enc_count = enc_count + lookup_table[enc_val & 0b1111];
}
which only outputted 0 on the serial port, interestingly however when i miss entered the code line
static int8_t lookup_table[] = {0.-1,1,0,1,0,0,-1,-1,0,0,1,0,1,-1,0};
(. instead of , in the array) the code only decreased the position variable for both directions of rotation on the shaft, however it seemed to be incrementing constantly with the shaft turning.
Now i'm aware that the Serial.print function utilizes a interrupt and this could cause missed pulses or just muddle things up with the ISR, however i have no idea how to trouble shoot with out it (if someone does i would love to hear your ideas).
also not sure if its relevant but my arduino sometimes has the error message, when i upload code
avrdude: stk500v2_ReceiveMessage(): timeout
I would appreciate anyones thoughts on how i might trouble shoot this issue.
