ESP8266 Community Forum

- Thu Oct 29, 2015 4:42 pm #32583 1. It should start blinking right after the powerup. The randomness is probably because of the missing pullup in question #2.
2. while MCP SDA/SCK pins are connected to GPIO2/GPIO0, simply add PullUps from those pins to VCC.

Also, you mentioned 47K resistors, it is a bit high/weak value. Use 4.7K instead, especially for I2C bus.

- Fri Oct 30, 2015 9:14 am #32621 Awesome, thank you! I'm going to hopefully be able to spend tonight, and the rest of the weekend if need be, getting everything in place as you recommended, and adding another 7 LEDs for testing to be sure I'm "good to go" with power.

I'll probably be back, but for now, again, thank you very much!

- Thu Oct 20, 2016 5:58 am #56830 I would like to know how you got the adafruit mcp23017 library to work on the esp. I am stuck right now. I can bit bang the pins and get it to work but I wish to use adafruits library. Could you please explain a little more?

Code: Select all#include <Wire.h>
#include "Adafruit_MCP23017.h"

Adafruit_MCP23017 mcp;
 
void setup() {
  Wire.pins(4, 5);
  mcp.begin();      // use default address 0

  mcp.pinMode(0, OUTPUT);
}


// flip the pin #0 up and down

void loop() {
  delay(500);

  mcp.digitalWrite(0, HIGH);

  delay(500);

  mcp.digitalWrite(0, LOW);
}

- Thu Oct 20, 2016 9:07 am #56838 It works fine for me !
Simply change your deprecated Wire.pins(4, 5) with Wire.begin(4, 5);