ESP8266 Community Forum

Posted: **Wed Apr 27, 2016 7:17 am**

I'm in the proces of building a web controlled cat feeder.

For that I need to control a stepper motor with a ESP-12. I want to create it in such a way that I can trigger the servo with a http call.

To connect the stepper motor to the ESP-12 I used a A3967 EasyDriver module and a LM1117 to convert the 5v coming out of the EasyDriver to 3.3v to power the ESP.

I hooked it up much like this, except for a arduino I used the ESP with pins 4 and 5:

When I upload a very basic sketch to make the stepper motor spin, it works like a charm:

Code: Select all

#include <AccelStepper.h>

// Define a stepper and the pins it will use
AccelStepper stepper(1, 5, 4);

int pos = 6600;

void setup()
{  
  stepper.setMaxSpeed(10000);
  stepper.setAcceleration(1000);
}

void loop()
{
  
  
  if (stepper.distanceToGo() == 0)
  {
    delay(500);
    pos = -pos;
    stepper.moveTo(pos);
  }
  stepper.run();
}

Now I want to do the same upon a http request, so I modified the code like this:

Code: Select all

#include <AccelStepper.h>
#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <ESP8266mDNS.h>


// Define a stepper and the pins it will use
AccelStepper stepper(1, 5, 4);

int pos = 6600;

const char* ssid = "hes";
const char* password = "somepw";

ESP8266WebServer server(80);

const int led = 13;

void handleRoot() {
  stepper.moveTo(6600);
  stepper.run();

  server.send(200, "text/plain", "running stepper!");
}


void setup(void){
  stepper.setMaxSpeed(10000);
  stepper.setAcceleration(1000);
  
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  Serial.println("");

  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());

  server.on("/", handleRoot);

  server.begin();
  Serial.println("HTTP server started");
}

void loop(void){
  server.handleClient();
}

Problem is that the HTTP server runs fine, but the stepper motor doesn't run. I feel it twitch a little bit when I do the HTTP request, but it doesn't spin like it should.
When I put the commands

stepper.moveTo(6600);
stepper.run();

inside the loop() function, it does make a spin upon boot.
Any idea where I'm going wrong?

Posted: **Wed Apr 27, 2016 8:22 am**

Probably that "stepper.run();" call should stay in the loop() and that handleRoot() should only call the moveTo().

Posted: **Fri Apr 29, 2016 10:35 am**

Thanks martinayotte, you where actually right. Moving the stepper.run(); into the loop indeed made it work. I however don't totaly understand why it doesn't work when stepper.run() is inside the handleRoot() function.

My next problem is that I need to mode the stepper twice (first reverse, than forward)

When I put two commands in the handleRoot() function like this:
stepper.move(-6000);
stepper.move(4600);

It seems that only the last one is actually executed, even when I call the run function from there:

stepper.move(-6000);
stepper.run();
stepper.move(-4600);
stepper.run();

Posted: **Fri Apr 29, 2016 11:15 am**

This library is time-driven, so it need to execute some codes once in awhile in background, a bit like the webserver, which is done in webserver.handle(), for the stepper library, it requires to run stepper.run() regularly in the loop(). You should never call it elsewhere than in the loop(). Also, never make the code inside the loop() hanging, otherwise it will freeze both the webserver and the stepper.

In your server.handleRoot() or any other callbacks, you simply need to send the stepper.move(), then wait a bit so that move is been executed, and then you can follow with the next move :

Code: Select all

stepper.move(-6000);
delay(500); // half second should be enough for this move ...
stepper.move(4600); 
delay(500);

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