IRIG Timecode encoding/decoding library for Arduino and STM32duino, IRIG has been implemented to the standards here

Support for both IRIG A and IRIG B, however the library does not support IRIG with year nor SBS in either IRIG A or IRIG B mode.

Warning Some embedded processors could have trouble with IRIG A due to its 100 microsecond precision requirement, a >20MHz processor is recommended, however I have been able to rather easily generate valid IRIG A signals on a 16MHz Arduino Uno, but the board struggles to receive them with a ~30% failure rate

• irig_simple_rx: Receives IRIG-B signals on pin 8, prints the timecode to serial
• irig_simple_tx: Transmits uptime as IRIG-B signal on pin 13
• ethernet_irig_ntp_client: Gets time via NTP, sends it via IRIG on pin 8

cd arduino/libraries
git clone https://github.com/abc123me/arduino_irig.git

struct irig_time_t {
	uint8_t secs = 0;
	uint8_t mins = 0;
	uint8_t hours = 0;
	uint16_t day_of_year = 0;
	uint8_t tenths_of_secs = 0;
	
	void fixup();
	void uptime();
	void add_ms(uint32_t tdiff_ms);
	void add_s(uint32_t tdiff_s);
	uint16_t to_strn(char* str, uint16_t n);
};

• secs: Seconds, from 0 to 60
• mins: Minutes, from 0 to 60
• hours: Hours, from 0 to 24
• day_of_year: Day of year, from 0 to 365
• tenths_of_secs: 1/10 Seconds, from 0 to 10

• fixup(): Called by IRIG_TX::send, makes sure time fields are in range
• uptime(): Copies current system uptime into struct
• to_strn(char* str, uint16_t n): Copies contents into str, up to n, returns length
• add_ms(uint32_t t) / add_s(uint32_t t): Adds a certain amount of time to the time struct

• #define IRIG_A 0: 1ms IRIG, frames should be sent every 100ms
• #define IRIG_B 1: 10x slower version of IRIG, frames should be sent every 1 second, not accurate to the tenth of a second
• If an invalid mode is specified, it will default to IRIG_B

• IRIG_TX(uint8_t mode): Constructor for the IRIG_TX class, takes a mode listed above
• begin(int16_t pin): Initialize output on pin
• send(irig_time_t timecode): Sends the timecode
• uint16_t getSendRate(): Gets the recommended interval in which to send timecodes

• IRIG_RX(uint8_t mode): Constructor for the IRIG_RX class, takes a mode listed above
• begin(int16_t pin): Initialize input on pin, iterrupts not yet supported
• uint8_t recv(irig_time_t* into): Receives timecode into into, returns 1 on success, blocks until a specified timeout has been reached (frame_time * 3 * 10)