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• Don't use TX and it's alive

  Johan Westlund • 08/22/2018 at 18:14 • 0 comments

  So GPIO1 aka TX is used for some special boot mode so it can't be pulldowned: https://bbs.espressif.com/viewtopic.php?t=796

  So I moved direction to gpio16 instead. Now I'm also getting a direction indicator on the NodeMCUs inbuilt LED that is connected to gpio16.

  I also had problem with gpio15 not being pulldowned enough when connected to DRV8825. So for now I removed it and shorted sleep and reset together to be controlled by the same pin.

  Found out that fault (that I pulled up) is connected to the sleep pin on the DRV8825. So have to remove it and see if it will work after.

  Test code:
  

  // Test sketch for drv8825 on NodeMCU v1.0
  
  // pinout definition for generic ESP-12E
  #define stepPin 3
  #define directionPin 16
  #define sleepPin 15
  #define resetPin 13
  #define m2_Pin 12
  #define m1_Pin 14
  #define m0_Pin 4
  #define enablePin 5
  #define faultPin 2
  #define endswitchPin 0
  
  #define MOTOR_STEPS 200
  
  void setStepSize() { //Going to add more later
    // Full step
    digitalWrite(m0_Pin, LOW);
    digitalWrite(m1_Pin, LOW);
    digitalWrite(m2_Pin, LOW);
  }
  
  void setup() {
  
    // REMEMBER THAT YOU CAN'T USE SERIAL FROM THIS POINT
    // DRV8825 has inbuilt pulldown resistors for all input pins. No need to set it.
    pinMode(stepPin, OUTPUT);
    pinMode(directionPin, OUTPUT);
    pinMode(sleepPin, OUTPUT);
    pinMode(resetPin, OUTPUT);
    pinMode(m2_Pin, OUTPUT);
    pinMode(m1_Pin, OUTPUT);
    pinMode(m0_Pin, OUTPUT);  
    pinMode(enablePin, OUTPUT);
  
    setStepSize();
    digitalWrite(resetPin, HIGH);
    digitalWrite(sleepPin, HIGH);
    digitalWrite(enablePin, LOW);
    
  }
  
  void loop() {
    // put your main code here, to run repeatedly:
    digitalWrite(directionPin, HIGH);
    for (int i = 0; i < MOTOR_STEPS; i++) {
      digitalWrite(stepPin, LOW);
      delay(10); //10 ms
      digitalWrite(stepPin, HIGH);
      delay(10); //10 ms
    }
    digitalWrite(directionPin, LOW);
    for (int i = 0; i < MOTOR_STEPS; i++) {
      digitalWrite(stepPin, LOW);
      delay(10); //10 ms
      digitalWrite(stepPin, HIGH);
      delay(10); //10 ms
    }
    delay(1000);
  }

   After flashing the code the motor is spinning 360 degrees and back again, wait 1 s and repeat.
  

  PROOF: https://www.facebook.com/beaverelectronics/videos/vb.161215301217651/242073909790273/?type=2&theater
  

  Going to add WiFi control, add better motor control, fix the small issues and test sleep in next step.
  

• How does the pins work

  Johan Westlund • 08/17/2018 at 11:33 • 0 comments

  This list is made with only mentioning how it handles digital logic and interrupts
  
  

  DRV8825: https://www.pololu.com/product/2133

  Pin	Function	Status
  EN	Logic high to disable device output and indexer	Input, Internal pulldown
  M0	Set step mode	Input, Internal pulldown
  M1	Set step mode	Input, Internal pulldown
  M2	Set step mode	Input, Internal pulldown
  RST	Logic low to reset indexer and disable output	Input, Internal pulldown
  SLP	Logic low to enter low-power sleep	Input, Internal pulldown
  STP	Rising edge move stepper one step	Input, Internal pulldown
  DIR	Logic level sets direction	Input, Internal pulldown
  FLT	Logic low when in fault condition	Output, open-drain, pullup to sleep pin

  Limit switch:

  Pin	Function	Status
  1	Endstop, need interrupt pin preferably	Output, Normaly Open

  This means that we need 8 outputs that doesn't have fixed pullups and can handle boot with pulldowns on the pins. And 2 interrupt inputs with at least one that has a pullup.
  

  As seen in the list below this means that D3 and D4 need to be inputs and one of the serial lines as output.

  NodeMCU v1.0 Amica ESP-12E:

  Pin	Function	Status	Can be used as
  D0	GPIO16	Not usable with deepsleep, Hi-Z DIO, no interrupt	Output
  D1	GPIO5	Hi-Z DIO	Output, Input, Interrupt
  D2	GPIO4	Hi-Z DIO	Output, Input, Interrupt
  D3	GPIO0	No Hi-Z DIO (prefere pullup)	Input, Interrupt
  D4	GPIO2	Don’t connect to ground at boot time (prefere pullup)	Input, Interrupt
  D5	GPIO14	Hi-Z DIO	Output, Input, Interrupt
  D6	GPIO12	Hi-Z DIO	Output, Input, Interrupt
  D7	GPIO13	Hi-Z DIO	Output, Input, Interrupt
  D8	GPIO15	Can't have pullup (only pulldown DIO)	Output
  RX	GPIO3	Not usable during Serial transmission	Output, Input, Interrupt (if serial not used)
  TX	GPIO1	Not usable during Serial transmission, Don’t connect to ground at boot time	Output, Input, Interrupt (if serial not used)
  A0	ADC0	Analog	Not usable as DIO
  SD3	GPIO10	Might be connected to flashmemory!!!	Not usable
  SD2	GPIO9	Might be connected to flashmemory!!!	Not usable
  SD1	MOSI		Unknown
  CMD	CS		Unknown
  SDO	MISO		Unknown
  CLK	SCLK		Unknown
  EN	Enable	DigitalWrite/Read not possible	Not usable
  RST	Reset	DigitalWrite/Read not possible	Not usable

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