:: Code Library and Tutorials ::
This code is not specific to any external devices. Code for that is found in InterfacingWithHardware. Here you find general use software snippets and libraries for calculations and 'internal' purposes.

Code Snippets and Utility Libraries.

AVR Related

• Useful AVR commands for getting the job done
• Interrupts
  • Arduino Interrupts - comprehensive explanation of the use of timers (from uCHobby).
  • How to use Interrupts in Arduino.
  • Interrupts example.
  • PcInt - simple pin change interrupt example.
• Timer code
  • Timer1 - Pwm, interrupt and other utilities for timer1.
  • MsTimer2 - library to use Timer2 on milliseconds.
  • Adjusting Arduino PWM Frequencies

Protothreading, Timing & Millis

• Metro Lib: Implementation of recurring timed events like blinking LEDs or servo motor control
• TimedAction a resource-friendly library for Timed Actions that occur every x millisecond.
• DateTime library Software real time clock
• EventFuse: Recurring clocked events via a count-down fuse
• The Tween class for ramps (PWM fades, for instance)
• millis() rollover handling: a function for detecting and handling rollover of the millis() function.
• Prescaler-related utility library : easy get/set of the prescaler + alternative functions to millis() / delay()
• heartbeat sketch - use an array to create an irregular blink pattern
• Stopwatch: doing multiple things at the same time.
• Scheduler: Javascript timer functions ported to Arduino to call your functions when you want them to be called.
• DCF77: DCF77 Library v.0.1 beta - March 2010.

Input / Output

• PWM Techniques
  • SoftPWM - Software based PWM library that moves any pin between any 2 states (low, high, high impedence, or pull up)
  • PWMallPins - here's how to get more PWM pins
  • atmega_i2c_pwm_expander - Use an ATmega as a PWM expander, controlled by I²C
  • 8-bit PCM audio (on a PC speaker)
• Metrology
  • Simple voltmeter class : uses the internal reference voltage (1.1V) to get an absolute voltage reading; can even be used to read own power source voltage value
  • A one led voltmeter: so as to say the voltmeter of the poor
  • LCD voltmeter: so as to say the voltmeter of the rich
  • Capacitance Meter
  • Logic Analyzer: a very simple logic analyzer. 1024 samples at 5.3 MHz
• Sensor Functions
  • getOneWireTemp
  • OneWire Interface (Dallas Semiconductor)
  • OneWire Interface (Atmel QTouch)
• PID Control
  • Arduino PID Library
• Ultrasonic Sensors
  • Ping: Simplify the usage of Ping))) Ultrasonic Sensors
• Using multiple devices (including Arduinos!) on an I2C bus
• Getting multiple Serial channels with an Arduino
• Charlieplexing
  • Charlieplex is a library which simplifies the coding of charlieplexed networks.
• PIN register based pin toggle library DigitalToggle

Storage

• RAM and EEPROM
  • Tricks for using the hidden EEPROM and Flash memory
  • A function for seeing how much memory (RAM) is available
  • A set of functions to dynamically allocate arrays
  • DB A simple database library for reading and writing to tables stored in EEPROM
  • EDB An extended database library based on DB allowing for more records, larger records size, and external EEPROM storage
• Read-only Flash ("PROGMEM") storage
  • Mikal Hart's Flash library allows you to easily store strings, arrays, and tables in read-only memory without the hassle and complexity of learning PROGMEM programming.
  • PROGMEM - top secret information too shocking to be included in the official reference section

Communication

• Serial
  • Streaming output: A simple way to get <<-style output with Serial/LCD/Ethernet/etc.
  • SerialDebugger is a library that ebhances code readability, and debug control.
  • NewSoftSerial: An interrupt-driven alternative to the core SoftSerial library.
  • SerialIP provides Internet connectivity over the serial port (no shields required)
• Twitter
  • TwitterLibrary assists in posting your data to twitter

General

• Unit Testing
  • ArduinoUnit
• Resource Friendly Datastructures
  • Resource friendly structs that contain useful data in a small useful packet.
• String Functions
  • FloatToString
  • FloatToString (Improved version 27/01/2009) in this thread.
  • tempToAscii
  • PString: A very lightweight string class that enables printing to buffer using the same code as Serial.print().
  • printf() simple shell around vsnprintf() letting you use send printf style format strings over serial.
• Behavior based programs
  • Behavior based programs: A framework for describing control logic as Behavior classes.
• Finite State Machine
  • Finite State Machine Library from johnw188
  • Finite State Machine Library that requires no source editing.

Math

• Prime number generator
• Smoothing Functions
  • smooth(data, filterVal, smoothedVal) - a low-pass filter smoothing function, useful for removing sensor jitter
  • digitalSmooth(data, smoothArrayName) - a digital low-pass filter smoothing function, useful for removing sensor jitter, and glitches
• Mapping Functions
  • autoscale - scale a variable between two ranges using linear interpolation
  • fscale - a function to map a variable between two floating point ranges.
    Has a parameter to logarithmically favor either end of the output range
  • smoothstep - a function to ease from one value to the next with a smooth "s" shaped logarithmic curve.
• Random Functions
  • randomHat() - choose every number from a "hat" before repeating
  • randomWalk(stepSize) - wander between endpoints at a specified rate
• Frequency Related
  • Frequency Generation
    • Frequency generation using a hardware timer to drive a pin accurately or generate a periodic interrupt calling a function you supply.
    • freqout(freq, duration) - a simple frequency generator
    • Musical Algo Fun :: Making music with old PC speakers
    • Armstrong Music System - a collection of input and output abstractions to ease the development of musical instruments with the Arduino. This abstraction also allows sounds trigger remote hardware (PC or synthesizer) without additional coding.
    • Also see Interfacing with Hardware/Output/Audio
  • Frequency Measurement
    • Arduino Frequency Counter
    • Pulse Width Determination

Tutorials and Resources

These aren't code for a particular function, but rather tutorials on various aspects of C/C++.

Navigation

• AVR Related
• Protothreading, Timing & Millis
• Input / Output
• Storage
• Communication
• General
• Math

AVR Related

• Let the arduino sleep.
• C language
  • A very good summary of the C language (.pdf)
  • Reference for the standard C API (libc).
    To use with Arduino, add the appropriate #include to the top of your sketch and use the functions as documented in the manual.
  • Variable Cope
    • An explanation of the parts of a sketch that can "see" a particular variable. For example, some variables are global, some are contained within a particular function, etc. Variable Scope
• Port Manipulation
  • More explanation of ports and manipulating them with bitwise operators.
    Port Manipulation

Protothreading, Timing & Millis

• This section needs to be extended

Input / Output

• Charlieplexing
• This section needs to be extended | see Input / Output from the Code Snippets and Utility Libraries section for ideas and example code.
• Creating a Web Activity Monitor using Arduino & 8x8 LED Matrix Tutorial

Storage

• This section needs to be extended | see Input / Output from the Code Snippets and Utility Libraries section for ideas and example code.

Communication

• This section needs to be extended | see Input / Output from the Code Snippets and Utility Libraries section for ideas and example code.

General

• Library Creation
  • Arduino Library Tutorial
  • Library Tutorial
  • How to extend libraries using Hierarchy
  • How to write Hardware Abstraction libraries
• Pointers
  • One of the most powerful and confusing aspects of C programming, pointers provide low-level access to memory. For information on using pointers, see this chapter from Practical C Programming.

Math

• Bit Math Tutorial
  • Learn how to decipher all those cryptic formulas you see in C code that use symbols like &= and <<. Start using bitwise operators in your own code to save memory and perform sophisticated low-level operations on your microcontroller hardware.