Switch branches/tags
Nothing to show
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
255 lines (224 sloc) 9.24 KB
/* This one is not using any PinChangeInterrupt library */
This program uses an Arduino for a closed-loop control of a DC-motor.
Motor motion is detected by a quadrature encoder.
Two inputs named STEP and DIR allow changing the target position.
Serial port prints current position and target position every second.
Serial input can be used to feed a new location for the servo (no CR LF).
Pins used:
Digital inputs 2 & 8 are connected to the two encoder signals (AB).
Digital input 3 is the STEP input.
Analog input 0 is the DIR input.
Digital input 4 is the HOME output. asserted if encoder0Pos is smaller than one.
Digital outputs 9 & 10 control the PWM outputs for the motor (I am using half L298 here).
Please note PID gains kp, ki, kd need to be tuned to each different setup.
#include <EEPROM.h>
#include <PID_v1.h>
#define encoder0PinA 2 // PD2;
#define encoder0PinB 8 // PC0;
#define M1 9
#define M2 10 // motor's PWM outputs
#define ENDSTOP 4
#define STEP 3
byte pos[1000]; int p=0;
double kp=3,ki=0,kd=0.0;
double input=0, output=0, setpoint=0;
PID myPID(&input, &output, &setpoint,kp,ki,kd, DIRECT);
volatile long encoder0Pos = 0;
boolean isHome=true;
boolean auto1=false, auto2=false,counting=false;
long previousMillis = 0; // will store last time LED was updated
long target1=0; // destination location at any moment
//for motor control ramps 1.4
bool newStep = false;
bool oldStep = false;
bool dir = false;
byte skip=0;
// Install Pin change interrupt for a pin, can be called multiple times
void pciSetup(byte pin)
*digitalPinToPCMSK(pin) |= bit (digitalPinToPCMSKbit(pin)); // enable pin
PCIFR |= bit (digitalPinToPCICRbit(pin)); // clear any outstanding interrupt
PCICR |= bit (digitalPinToPCICRbit(pin)); // enable interrupt for the group
void setup() {
pinMode(encoder0PinA, INPUT_PULLUP);
pinMode(encoder0PinB, INPUT_PULLUP);
attachInterrupt(0, encoderInt, CHANGE); // encoder pin on interrupt 0 - pin 2
attachInterrupt(1, countStep , RISING); // step input on interrupt 1 - pin 3
TCCR1B = TCCR1B & 0b11111000 | 1; // set 31Kh PWM
Serial.begin (115200);
//Setup the pid
homing(); // comment if you don't want homming on reset
help(); // display help
/* enables to detect obstacles such as hard stops or soft rubber stops
* without the use of a limit switch since it looks at the growing error
* when such an event occurs.
* an output pin is asserted after stop is detected for 2 seconds
void homing(){
long tstamp;
long error=0;
int scanning_steps=20; // how fast you want to scan for home
int max_error;
float homing_power=1.00; // power multiplicator for homing. suggested between 0.1 for 10% and 1 for 100%
digitalWrite(ENDSTOP,0); // Turn external pin low
Serial.println("homing ...");
while( error>-max_error){ // loop while error is less than max_error an obstacle or rubber stopper will make the error increase at each interval
if(millis()-tstamp>7) // decreasetarget at desired time interval (6 default)
setpoint-=scanning_steps; //decrease target
tstamp=millis(); //stamp the time
Serial.print("setpoint "); Serial.print(setpoint);
Serial.print(" encoder "); Serial.print(input);
Serial.print(" error "); Serial.println(error);
input = encoder0Pos;
while(!myPID.Compute()); // wait till PID is actually computed
encoder0Pos=-50; // detected limit is now -70 to (if a soft limit is set like rubber motor would always try to push if zer0)
target1=0; // target is now the new zero
void loop(){
input = encoder0Pos;
{endstop();} // wait till PID is actually computed in the mean time assert the endstop pins
if(Serial.available()) process_line(); // it may induce a glitch to move motion, so use it sparingly
if(input==setpoint)pwmOut(0); else pwmOut(output);
if(auto1) if(millis() % 1000 == 0) target1=random(9000); // that was for self test with no input from main controller
if(auto2) if(millis() % 1000 == 0) printPos();
//if(counting && abs(input-target1)<15) counting=false;
if(counting && (skip++ % 5)==0 ) {pos[p]=encoder0Pos; if(p<999) p++; else counting=false;}
endstop(); // output status of endstop
void pwmOut(int out) {
if(out<0) { analogWrite(M1,0); analogWrite(M2,abs(out)); }
else { analogWrite(M2,0); analogWrite(M1,abs(out)); }
const int QEM [16] = {0,-1,1,2,1,0,2,-1,-1,2,0,1,2,1,-1,0}; // Quadrature Encoder Matrix
static unsigned char New, Old;
ISR (PCINT0_vect) { // handle pin change interrupt for D8
Old = New << 2;
New = (PINB & 1 )+ ((PIND & 4) >> 1); //
encoder0Pos+= QEM [Old + New];
void encoderInt() { // handle pin change interrupt for D2
Old = New << 2;
New = (PINB & 1 )+ ((PIND & 4) >> 1); //
encoder0Pos+= QEM [Old + New];
void countStep(){ if (PINC&B0000001) target1--;else target1++; } // pin A0 represents direction
void process_line() {
char cmd =;
if(cmd>'Z') cmd-=32;
switch(cmd) {
case 'P': kp=Serial.parseFloat(); myPID.SetTunings(kp,ki,kd); break;
case 'D': kd=Serial.parseFloat(); myPID.SetTunings(kp,ki,kd); break;
case 'I': ki=Serial.parseFloat(); myPID.SetTunings(kp,ki,kd); break;
case '?': printPos(); break;
case 'X': target1=Serial.parseInt(); p=0; counting=true; for(int i=0; i<300; i++) pos[i]=0; break;
case 'T': auto1 = !auto1; break;
case 'A': auto2 = !auto2; break;
case 'Q': Serial.print("P="); Serial.print(kp); Serial.print(" I="); Serial.print(ki); Serial.print(" D="); Serial.println(kd); break;
case 'H': help(); break;
case 'W': writetoEEPROM(); break;
case 'K': eedump(); break;
case 'R': recoverPIDfromEEPROM() ; break;
case 'S': for(int i=0; i<p; i++) Serial.println(pos[i]); break;
case 'L': homing(); break;
while(!=10); // dump extra characters till LF is seen (you can use CRLF or just LF)
void printPos() {
Serial.print(F("Position=")); Serial.print(encoder0Pos); Serial.print(F(" PID_output="));
Serial.print(output); Serial.print(F(" Target=")); Serial.print(setpoint);
if(!isHome) Serial.print(" NOT"); Serial.println(" home");
void help() {
Serial.println(F("\nPID DC motor controller and stepper interface emulator"));
Serial.println(F("by misan"));
Serial.println(F("Available serial commands: (lines end with CRLF or LF)"));
Serial.println(F("P123.34 sets proportional term to 123.34"));
Serial.println(F("I123.34 sets integral term to 123.34"));
Serial.println(F("D123.34 sets derivative term to 123.34"));
Serial.println(F("? prints out current encoder, output and setpoint values"));
Serial.println(F("X123 sets the target destination for the motor to 123 encoder pulses"));
Serial.println(F("T will start a sequence of random destinations (between 0 and 2000) every 3 seconds. T again will disable that"));
Serial.println(F("Q will print out the current values of P, I and D parameters"));
Serial.println(F("W will store current values of P, I and D parameters into EEPROM"));
Serial.println(F("H will print this help message again"));
Serial.println(F("A will toggle on/off showing regulator status every second"));
Serial.println(F("L will execute homing\n"));
void writetoEEPROM() { // keep PID set values in EEPROM so they are kept when arduino goes off
double cks=0;
for(int i=0; i<12; i++);
Serial.println("\nPID values stored to EEPROM");
void recoverPIDfromEEPROM() {
double cks=0;
double cksEE;
for(int i=0; i<12; i++);
if(cks==cksEE) {
Serial.println(F("*** Found PID values on EEPROM"));
else Serial.println(F("*** Bad checksum"));
void eeput(double value, int dir) { // Snow Leopard keeps me grounded to 1.0.6 Arduino, so I have to do this :-(
char * addr = (char * ) &value;
for(int i=dir; i<dir+4; i++) EEPROM.write(i,addr[i-dir]);
double eeget(int dir) { // Snow Leopard keeps me grounded to 1.0.6 Arduino, so I have to do this :-(
double value;
char * addr = (char * ) &value;
for(int i=dir; i<dir+4; i++) addr[i-dir];
return value;
void eedump() {
for(int i=0; i<16; i++) { Serial.print(,HEX); Serial.print(" "); }Serial.println();
void endstop (){
// endstop detection. it is interlocked. under normal operation it would not
// send a digital write, just on transition smaller than 2;
// this would not significantly affect normal operation.
else if(encoder0Pos>0&&isHome)