Shrinkify Arduino using Cheap ATtiny13A Microcontroller

You can shrinkify your simple Arduino project into ultra tiny ATtiny13A microcontroller as long as your project code size doesn't exceed 1 Kb limit of ATtiny13A, and it doesn't use RAM / EEPROM over 64 bytes . Why would you do that? Because two important reason: it's cheap (vcc2gnd.com sell this microcontroller for as low as $1.5 / Rp17.000,- for Indonesian customer, even tinier and cheaper for SOIC version), and it certainly has much smaller form than your ordinary Arduino, even compared with Arduino smallest form (Arduino Micro).

If you need more power (bigger program code space, bigger RAM), you should consider using bigger version of ATtiny such ATtiny2313, but that's another story. For now let's focus with ATtiny13A (note that "A" suffix means newer version of ATtiny13 series, older version has no such suffix). Also note that for serious design / commercial product, you really should consider using newer series such ATtiny45 or ATtiny85 (same form factor with bunch of new capabilities).

To program any AVR tiny microcontrollers you can use SPI-based programmer such usbASP, or use your existing SPI-enabled board such Arduino (using ArduinoISP sketch, see following picture to see how simple it is to connect ATtiny13A to your Arduino)...