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March 02, 2025 23:17
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Particle Photon Cheatsheet

A comprehensive cheat sheet for the Particle Photon, covering its key features, setup, coding, and cloud integration. This guide provides a quick reference for developers working with the Photon for IoT projects.

Photon Basics & Setup

Hardware Overview

Particle Photon: A small Wi-Fi enabled development kit for creating connected projects.

Key Features:

  • Broadcom Wi-Fi chip
  • STM32 ARM Cortex M3 microcontroller
  • Built-in RGB LED (D7)
  • Headers for easy prototyping

Setting up the Photon

  1. Particle Account: Create an account at particle.io.
  2. Particle CLI: Install the Particle Command Line Interface (CLI) using npm:

npm install -g particle-cli
3. **Claiming the Device:** Use the Particle CLI to claim the device to your account. Put your Photon in listening mode (blinking blue) by holding the SETUP button. Then run:bash
particle setup
```
Follow the prompts to connect to your Wi-Fi network.

Important Pins

D0-D7:

Digital I/O pins

A0-A7:

Analog input pins

TX/RX:

Serial communication pins

VIN:

Voltage Input (3.6V - 12V)

3V3:

3.3V output

GND:

Ground

Coding with the Photon

Basic Structure 

// Setup function (runs once)
void setup() {
  // Initialize code here
}

// Loop function (runs repeatedly)
void loop() {
  // Main program code here
}

Digital I/O

pinMode(pin, mode);

Sets the mode of a digital pin (INPUT, OUTPUT, INPUT_PULLUP)

digitalWrite(pin, value);

Writes HIGH or LOW to a digital pin

digitalRead(pin);

Reads the value (HIGH or LOW) from a digital pin

Example:

 
pinMode(D7, OUTPUT);
digitalWrite(D7, HIGH); // Turn LED on
delay(1000);
digitalWrite(D7, LOW);  // Turn LED off

Analog I/O

analogRead(pin);

Reads the analog value (0-4095) from an analog pin

analogWrite(pin, value);

Writes an analog value (PWM) to a digital pin (0-255)

Example:

 
int sensorValue = analogRead(A0);
analogWrite(D0, sensorValue / 16); // Map 0-4095 to 0-255

Timing

delay(ms);

Pauses the program for a specified number of milliseconds

millis();

Returns the number of milliseconds since the program started running

micros();

Returns the number of microseconds since the program started running

Cloud Functions & Variables

Cloud Functions

Cloud functions allow you to call functions on your Photon from the Particle Cloud API.

int myFunction(String command) {
  // Function logic here
  return 1; // Return a value
}

// Register the function
Particle.function("myFunction", myFunction);

Accessing the Function via the API:
particle call <device_name> myFunction "argument"

Cloud Variables

Cloud variables allow you to read variables from your Photon via the Particle Cloud API.

int myVariable = 0;

// Register the variable
Particle.variable("myVariable", myVariable);

Accessing the Variable via the API:
particle get <device_name> myVariable

Publishing Events

Publishing events allows you to send data from your Photon to the Particle Cloud.

Particle.publish("eventName", "data");

You can also specify the event’s privacy:

Particle.publish("eventName", "data", PRIVATE);

Options are PRIVATE or PUBLIC.

Networking & System

Checking Connection Status

WiFi.ready()

Returns true if the Wi-Fi connection is established and the Photon is connected to the Particle Cloud.

Particle.connected()

Returns true if the Photon is connected to the Particle Cloud.

System Functions

System.reset();

Resets the Photon.

System.dfu();

Puts the Photon in DFU (Device Firmware Upgrade) mode for flashing firmware via USB.

System.sleep(sleep_mode, sleep_time);

Puts the Photon in a low-power sleep mode. sleep_mode can be SLEEP_MODE_DEEP or SLEEP_MODE_SOFTAP. sleep_time is in seconds.

Error Handling

Use TRY() and CATCH() to handle errors. assert() also can be used to check if the statement returns true.