Arduino: Why doesn't my stepper move in reverse direction? - arduino

Question

I have verified that its not a wiring problem by using some non library example code, so it seems the problem is not with the circuit.
I'm expecting the following code to run the motor in one direction 200 steps then run 200 steps in the opposite direction. It seems to run the initial 200 steps but then stops, why?
In the setup function:
stepper.setCurrentPosition(0);
// Set the maximum speed in steps per second:
stepper.setMaxSpeed(1000);
In the loop function:
while(stepper.currentPosition() < 300){
stepper.moveTo(200);
stepper.setSpeed(200);
stepper.run();
if (stepper.distanceToGo() == 0) {
stepper.moveTo(-stepper.currentPosition());
stepper.setSpeed(200);
stepper.run();
}
}
Here's my entire code. The if/else at the bottom is where I want to run the motor. I've put in some non working example code in this block as an example:
#include <deprecated.h>
#include <MFRC522.h>
#include <MFRC522Extended.h>
#include <require_cpp11.h>
// Include the AccelStepper library:
#include <AccelStepper.h>
// constants won't change. They're used here to set pin numbers:
const int BUTTON_PIN = 2; // the number of the pushbutton pin
#define BLUE 7
#define GREEN 6
#define RED 3
#define RST_PIN 9 // Configurable, see typical pin layout above
#define SS_PIN 53 // Configurable, see typical pin layout above
#define dirPin 10
#define stepPin 11
#define motorInterfaceType 1
// Variables will change:
String authKeyFob = "123456789";
String card_ID="";
int ledState = 0; // remember current led state
int buttonState = 0;
int oldButtonState = 0;
bool toggle = false;
MFRC522 mfrc522(SS_PIN, RST_PIN); // Create MFRC522 instance
AccelStepper stepper = AccelStepper(motorInterfaceType, stepPin, dirPin);
void setup() {
// initialize serial communication at 9600 bits per second:
Serial.begin(9600);
while (!Serial); // Do nothing if no serial port is opened (added for Arduinos based on ATMEGA32U4)
SPI.begin(); // Init SPI bus
mfrc522.PCD_Init(); // Init MFRC522 card
// initialize the pushbutton pin as an pull-up input
// the pull-up input pin will be HIGH when the switch is open and LOW when the switch is closed.
pinMode(BUTTON_PIN, INPUT);
pinMode(GREEN, OUTPUT);
pinMode(RED, OUTPUT);
pinMode(BLUE, OUTPUT);
stepper.setCurrentPosition(0);
stepper.setMaxSpeed(1000);
stepper.setAcceleration(50);
// stepper.setSpeed(200);
// stepper.moveTo(200);
}
void loop() {
/*
// Change direction once the motor reaches target position
if (stepper.distanceToGo() == 0) {
stepper.moveTo(-stepper.currentPosition());
}
// Move the motor one step
stepper.run();
*/
buttonState = digitalRead(BUTTON_PIN);
// read the state of the switch/button:
oldButtonState = LOW; // NEED TO ADD A DECLARATION FOR THIS BEFORE SETUP
buttonState = digitalRead(BUTTON_PIN);
// Look for new cards, and select one if present
if (!mfrc522.PICC_IsNewCardPresent() ) {
}
if(mfrc522.PICC_ReadCardSerial() ){
card_ID="";
for (byte i = 0; i < mfrc522.uid.size; i++) {
card_ID += mfrc522.uid.uidByte[i];
}
if(card_ID == authKeyFob){
toggle = !toggle;
delay(200);
}
}
// if the button just became pressed...
if(buttonState == HIGH && oldButtonState==LOW){
toggle = !toggle; // same thing, toggle our variable.
delay(200);
}
if (toggle) {
digitalWrite(GREEN, HIGH);
digitalWrite(RED, LOW);
stepper.moveTo(200);
stepper.setSpeed(200);
stepper.run();
} else {
digitalWrite(GREEN, LOW);
digitalWrite(RED, HIGH);
stepper.moveTo(200);
stepper.setSpeed(200);
stepper.run();
}
oldButtonState = buttonState; // save the button state for next time
}

Answer 1

The run method doesn't block. It just takes one step if it is time. So let's step through your code. First we enter the while loop and tell it to step to 200 and set the speed and call run. We keep repeating that over and over. If we get to a point where we have 0 to go then you say moveTo the negative position, set the speed, call run once and then the while loop exits and repeats. On that repeat we say move to 200 and start calling run on that. So you're only calling run once with the moveTo set to the negative number.
You need to rethink the logic on this. I don't know what else is in your loop, so it's hard to say what exactly you want. If you really insist on it being blocking in the while loop then:
stepper.moveTo(200);
stepper.setSpeed(200);
while(stepper.distanceToGo() != 0){
stepper.run();
}
stepper.moveTo(-200);
while(stepper.distanceToGo != 0){
stepper.run();
}

Answer 2

This code moves the stepper in each direction.
if (toggle) {
digitalWrite(GREEN, HIGH);
digitalWrite(RED, LOW);
while(stepper.currentPosition() <= 200){
stepper.moveTo(200);
stepper.setSpeed(200);
stepper.runSpeedToPosition();
if(stepper.currentPosition()==200){
break;
}
}
} else {
digitalWrite(GREEN, LOW);
digitalWrite(RED, HIGH);
while(stepper.currentPosition() >= -200){
stepper.moveTo(-200);
stepper.setSpeed(200);
stepper.runSpeedToPosition();
if(stepper.currentPosition()==-200){
break;
}
}
}