Issue with #include <Wire.h> Causing Code to Fail When Using DRV8825 and AccelStepper

Using Arduino Programming Questions
1

I'm working on a project where I'm using the DRV8825 stepper motor driver with the AccelStepper library. I've got the Enable pin of the DRV8825 attached to a PCF8575 I2C multiplexer. I used the below code and it works perfectly, but not if I test with the multiplexer, and I've discovered that the stepper doesn't move even if I just include <PCF8575.h> (or even #include <Wire.h>) in the code. Any ideas how I can solve this?

#include "AccelStepper.h"
// #include <PCF8575.h>
// PCF8575 pcf8575(PCF8575_ADDR);

// Define stepper motor connections and motor interface type. Motor interface type must be set to 1 when using a driver:
#define dirPin 17
#define stepPin 21
#define motorInterfaceType 1

// Create a new instance of the AccelStepper class:
AccelStepper stepper = AccelStepper(motorInterfaceType, stepPin, dirPin);

void setup() {
  Serial.begin(9600); 
  stepper.setMaxSpeed(1000);
}

void loop() {
  stepper.setSpeed(250);
  stepper.runSpeed();
}
2

Why?
Which Arduino? Post a wiring diagram.

3

Most likely a pin assignment conflict. Make a list of all the pin assignments in each code and library module, which in turn depends on which Arduino you have.

4

My bad, I'm using an Arduino nano, here's a schematic.

form_q

5

Do those assignments make sense for a Nano?

1 Like
6

From your schematic, shouldn't

be

#define dirPin 5
#define stepPin 9

?

7

The ENABLE pin must be pulled LOW for the motor to run, is the PCF8575 doing that?