Useful links - check here for reference posts / tutorials

[nickgammon]

How to ask a good question

• How to use this forum
  Tips on using this forum effectively, including uploading images, code, attachments. Also tips on asking good questions, in such a way as to get a good answer.

• Read before posting a programming question
  Tips for how to formulate a good question, including using code tags for your code.

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General design

• Blink without delay (YouTube video) *
  An 11-minute YouTube tutorial about state machines and blinking LEDs without using delay().

• Planning and Implementing an Arduino Program
  Tips for planning and organizing your program, from scratch.

• How to do several things at a time
  Tips for doing several things "at once" like testing switches, flashing LEDs, and controlling motors. Also illustrates the use of millis() to manage timing without blocking

• How to do multiple things at once *
  Another thread about doing multiple things "at the same time".

• State machines *
  Discussion about "state machines" which are ways of managing complex logic situations easily, by Nick Gammon.

• State machines *
  Another tutorial about state machines, by Mike Cook.

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Communications

• I2C *
  Information about the I2C hardware and protocol, widely used to communicate with various peripheral chips.

• PC to Arduino comms
  Discussions about sending text or binary data from an Arduino to a PC, or vice-versa, using Python.

• Radio/Wireless Transceivers Interfacing *
  How to interface using RF24L01 2.4GHz transceivers, by Terry King.

• Serial Input Basics
  An introduction to using the serial ports on your Arduino, including sending and receiving multiple bytes.

• Serial data - how to process without blocking *
  Suggested techniques for receiving incoming serial data, without "blocking" (waiting).

• SPI *
  Information about the SPI hardware, widely used to communicate with other chips, shift registers, LCD displays, etc.

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C++ programming

• Arduino functions reference
  The official reference page for commonly-used functions, like digitalWrite.

• AVR Libc Home Page *
  Standard library functions supplied with the IDE, such as CRC checks, EEPROM handling, watchdog timer, sleep management, and much more.

• Function variables *
  A discussion about how to store function addresses in variables, and how to make "callback" functions, so that one function can call another one, from a variable.

• millis() overflow ... a bad thing? *
  A discussion of how to manage when millis() and micros() overflow.

• Tips, traps and style guide *
  A list of common problems encountered by beginners, such as confusing comparison with assignment.
  Also describes how to disassemble your code, where libraries are located, and other information.

• What is Scope?
  A discussion of the use of variables in C++ programs, focussing on their scope and lifetime. Discussions include local and global variables, and the use of the extern keyword.

• Using PROGMEM *
  A discussion about putting strings and other data types into Program Memory (PROGMEM), to save RAM.

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Hardware

• Arduino Basic Connections *
  Very useful site listing different ways of connecting hardware to your Arduino (schematics).

• De-coupling capacitors *
  Why the use of de-coupling capacitors is essential.

• Interrupts *
  A discussion about the use of interrupts on the Arduino, including hints and pitfalls.

• LDRs and IR LEDs (PDF: 862.7 KB)
  Tutorial on sending and receiving information using light (IR LEDs and LDRs)

• LEDs *
  Why you need current-limiting resistors when driving LEDs

• Pin-outs - assorted *
  Pin-outs for various boards done by PighiXXX (of Arduino Basic Connections fame) (JavaScript required)

• Pin-outs - Uno
  Pin-outs for the Uno board (SPI / I2C etc.)

• Pin-outs - Mega2560
  Pin-outs for the Mega2560 board (SPI / I2C etc.)

• Power saving *
  A discussion about running in low-power mode using sleep modes, the watchdog timer, and general tips for reducing power consumption.

• Rotary encoders tutorial
  Some suggested methods of handling rotary encoders.

• Stepper motors tutorial *
  A tutorial covering the basic principles of stepping motors and stepping motor control systems.

• Stepper motor basics
  An introduction to using stepper motors.

• Switches *
  Tips for wiring up switches, including debouncing and detecting status changes.

• Timers *
  An introduction to the hardware counters/timers.

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Datasheets

• Atmega48/88/168/328 datasheet (PDF - 32.9 MB - Rev. 8271J – Nov/2015) *

• Atmega640/1280/1281/2560/2561 datasheet (PDF - 8.8 MB - Rev. 2549Q - Feb/2014) *

• Atmega16U4/32U4 datasheet (PDF - 5.6 MB - Rev. 7766J – Apr/2016) *

• Atmega8U2/16U2/32U2 datasheet (PDF - 4.5 MB - Rev. 7799E – Sep/2012) *

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• Links to off-site information. That is, not on the Arduino Forum.

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Discussion: Call for a list of useful programming threads