Servo and Photon 2?

Hardware
1

The docs for the servo say " NOTE: Servo is only supported on Gen 3 devices in Device OS 0.8.0-rc.26 and later."

Does that mean that I can't use the servo on a Photon 2?

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2

Servo works on the P2, Photon 2, and M-SoM.

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3

Yup, I just got it to work, thank you! I know that there's servo.h, but my understanding is that behind the scenes the servo is using PWM. Is there any where I can see the source code that's behind the servo.h methods?

4

This is the implementation of the API

This is the platform-specfiic code for RTL872x:

5

I am having trouble getting a Servo to work on the Photon2 and feel silly about it. I can get the same servo to work on a Photon 1. DMM shows 5.0V on servo power pins. Blinking LED works fine (see code below).

Are there particular pins that PWM/Servos are restricted to? I have tried pins D0, D4, and D7. Does anything jump out at you about my code/example shown below?

Example Code that works on a Photon 1 and fails on a Photon 2:

#include "Particle.h"

Servo myServo;

//<snip> System Mode Semi_Automatic, Thread Enabled, Log Level Info

void setup() {
  myServo.attach(D0);
  pinMode(A5,OUTPUT);
  Log.info("Sending Hello World!");
}

void loop() {
  digitalWrite(A5,HIGH);
  myServo.write(10);
  delay(1000);

  digitalWrite(A5,LOW);
  myServo.write(170);
  delay(1000);
}
6

Hi @Phoenix

You should not have to use digitalWrite(), just the myservo.write() calls.

I think you are taking over the pin (A5) and not letting the servo PWM have the pin for output.

7

The digitalWrite() statements are just there to ensure that the code is uploaded correctly and running as expected. (They are sometimes called a heartbeat.)

The servo is attached to D0.

8

OK Sorry I read the code too quickly. The heartbeat is fine.

According the Photon2 datasheet, D0 is not a PWM pin and servo does not work on D0.

The PWM Pins are: D1, MISO (aka D16), MOSI (aka D15), A5 (hence my confusion), and A2.

Can you try using one of these pins? The pinout part of the datasheet is here:

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9

Bingo! Thank you!

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10

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