Why does LED Not blink as suggested by example ?

Other Hardware LEDs and Multiplexing
1

hi,
i've coded many things with led-output, but on the mc23017 expansion board
i cant getexamply work
here's code

// Blinks an LED attached to a MCP23XXX pin.
#include <Wire.h>
// ok to include only the one needed
// both included here to make things simple for example
//#include <Adafruit_MCP23X08.h>
#include <Adafruit_MCP23X17.h>

#define LED_PIN 0     // MCP23XXX pin LED is attached to

// only used for SPI
//#define CS_PIN 6

// uncomment appropriate line
//Adafruit_MCP23X08 mcp;
Adafruit_MCP23X17 mcp;

void setup() {
  Serial.begin(9600);
  //while (!Serial);
  Serial.println("MCP23xxx Blink Test!");

  // uncomment appropriate mcp.begin
  if (!mcp.begin_I2C()) {
  //if (!mcp.begin_SPI(CS_PIN)) {
    Serial.println("Error.");
    //while (1);
  }

  // configure pin for output
  mcp.pinMode(LED_PIN, OUTPUT);

  //Serial.println("Looping...");
  Serial.println("Setup ready");
}

void loop() {
  mcp.digitalWrite(LED_PIN, HIGH);
  delay(500);
  mcp.digitalWrite(LED_PIN, LOW);
  delay(500);
  Serial.println("loopy");
  delay(1500);
}

this code comes with the lib, in few lines adaption to my conditions on arduino nano

the serial output works just ok,
but i cant get led to blink, what was the easiest step on other situations.

i have tested with different pins, same result..

As i use an expansion board, i dont not know whether there are special things necessary,
documentation does not tell..

does anyone has experience with that ?

2

Does the MCP detected by i2c scanner code?

3

thanks
i guess,
mcp.begin() seems accepted and serial monitor shows loop message..

4

led on expansion board is enlighted..

5

Do you use a resistor with led?

6

Is the led wired with the correct polarity? Are you sourcing a voltage and current to the led which is connected to ground, or are you grounding the led which is getting voltage and current from a different supply?

7

hi,
yes, with 470 Ohm resistor, and i tested this
by connecting plus wire to gnd-pin of mc..., then it was enlighted.

8

sorry, i connedted minus-wire..

9

hi,
now i may spend some time to test further..
the i2c-scanner shows an adress 0x27 , the blink-sketch now
shows "error"

there are 6 pins at the jack
VCC
GND
SDA
SCL
INT A
INT B

the first 4 pins i guess are connected correctly,
otherwise the i2c-scanner would not find an adress ,ok ?

what to do with INT.. ?

the other pins are named PA0..PA and PB1..PB7
for pin 0 which PA.. oder PB.. on which the led must be connected ?

10

this last point is cleared now by reading Readme.md, so LED must be conntected to GPA0
via Resistor for the example..

11

hi,
meanwhile by using the i2c-scanner and reading the Readme.md
and modifying the wiring
it works fine !

this thread is now solved.