This TinyDecoder Is an IR Remote Receiver and NEC Decoder Powered by an ATtiny13A

Stefan Wagner has developed the TinyDecoder, a PCB device that receives infrared signals and displays their address and command on an OLED screen. The signal is decoded with the NEC IR transmission protocol that uses pulse distance encoding of the message bits.

Given that Wagner has already created an IR remote control based on an ATtiny13A, he decided to continue leveraging the same 8-bit MCU for the TinyDecoder that receives the IR signal via TSOP4838 (infrared receivers). The PCB runs on an LIR1220 coin cell battery as the 'normal' CR1220s weren't sufficient.

As mentioned earlier, the software portion of the project taking care of IR receiving and decoding works on the NEC protocol that utilizes the timer0 to measure the burst and pause lengths of the signal. Wagner also noted that even though the program was tested successfully on the TSOP4838, it can work on other available IR receivers that are tuned to 38 kHz carrier frequency as well.

"The I²C protocol implementation is based on a crude bit-banging method," Wagner says. "The functions for the OLED are adapted to the SSD1306 128x32 OLED module, but they can easily be modified to be used for other modules."

Since the board does not have any in-circuit serial programming header, Wagner adds that you'll have to program the ATtiny either before soldering using an SOP adapter, or after soldering with an EEPROM clip. The project is available on GitHub with more details on NEC and I2C protocol implementation.