Photon flashed once, now can't flash again

Troubleshooting
1

Ugh. Had a RED FLASH SOS + HARD FAULT. Resolved that using DFU mode and Particle Update. Yay.

So I wanted to test that things are OK. I flashed some test code using Particle Dev, and it seemed to upload fine.

// --------------------------------------
// i2c_scanner
//
// Version 1
//    This program (or code that looks like it)
//    can be found in many places.
//    For example on the Arduino.cc forum.
//    The original author is not know.
// Version 2, Juni 2012, Using Arduino 1.0.1
//     Adapted to be as simple as possible by Arduino.cc user Krodal
// Version 3, Feb 26  2013
//    V3 by louarnold
// Version 4, March 3, 2013, Using Arduino 1.0.3
//    by Arduino.cc user Krodal.
//    Changes by louarnold removed.
//    Scanning addresses changed from 0...127 to 1...119,
//    according to the i2c scanner by Nick Gammon
//    http://www.gammon.com.au/forum/?id=10896
// Version 5, March 28, 2013
//    As version 4, but address scans now to 127.
//    A sensor seems to use address 120.
//
// This sketch tests the standard 7-bit addresses
// Devices with higher bit address might not be seen properly.
//

//#include <Wire.h
#include "application.h"

int scanning_count = 0;

void setup()
{
  Wire.begin();

  Serial.begin(9600);
  Serial.println("\nI2C Scanner");

  pinMode(D7, OUTPUT);
  digitalWrite(D7, LOW);

}


void loop()
{
  byte error, address;
  int nDevices;

  scanning_count++;

  Serial.print(scanning_count);
  Serial.println(" Scanning...");

  nDevices = 0;
  for(address = 1; address < 127; address++ )
  {
    // The i2c_scanner uses the return value of
    // the Wire.endTransmisstion to see if
    // a device did acknowledge to the address.
    Wire.beginTransmission(address);
    error = Wire.endTransmission();

    if (error == 0)
    {
      Serial.print("I2C device found at address 0x");
      if (address<16)
        Serial.print("0");
      Serial.print(address,HEX);
      Serial.println("  !");


        digitalWrite(D7, HIGH);
        delay(1000);
        digitalWrite(D7, LOW);

      nDevices++;
    }
    else if (error==4)
    {
      Serial.print("Unknown error at address 0x");
      if (address<16)
        Serial.print("0");
      Serial.println(address,HEX);
    }
  }
  if (nDevices == 0)
    Serial.println("No I2C devices found\n");
  else
    Serial.println("done\n");

  delay(10000);           // wait 10 seconds for next scan
}

Note that this code works perfectly on a Particle Core.

However, the Photon starts to run the code through one loop() then flashes and re-starts running the loop().

So I want to play with it. Revised the code and tried to upload. Compiles OK, but now it won’t flash. I get ‘Flashing via the cloud…’, no response from the Photon, then a status of “undefined…”

My Photon is now breathing happily, then doing something - yellow? pulse, cyan? flash (I’m color blind, so guessing…), and breathing cyan again. And I can’t upload new code.

Is it possible it’s related to my i2c test code? Does this happen to anyone else? Any workarounds?

2

If you can’t distinguish the colors, just post a short video of it.

The delay(10000) will also not help with OTA flashing.

3

SOLUTION (part 1) - I was able to flash new code by entering Safe Mode:

To put your device in Safe Mode:
• Hold down BOTH buttons
• Release only the RESET button, while holding down the SETUP button.
• Wait for the LED to start blinking magenta
• Release the SETUP button

This put the Photon in a state that was easily flashed.

ISSUE (color flashes) - Here are the two flashes that I'm getting when I run the code above:

&

PROBLEM (I2C issue) - Code that eliminates the Wire.beginTransmission(); and Wire.endTransmission(); statements just sits there, prints to Serial.print(), and pulses like it should.

So I'll start trying to dissect what the problem is, and will update. I've noticed I2C issues previously.

4

SOLUTION (part 2) - Looks like the flashing was happening because I tried running my i2c test code (i2c_scanner) on a bare Photon sitting on my desk, no SCL/SDA pull-up resistors in sight.

After I plugged it into my old protoboard that has pull-ups to both I2C pins, I’m getting a nice pulsing cyan with no flashes, like I should.

So that’s good.

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