This is a hh:mm:ss
clock that runs from the time contained in NMEA RMC sentences.
The code is targeted at an Atmel ATTiny13A.
Notes:
-
As the target microcontroller doesn't have enough RAM to store a full NMEA sentence, this project uses a custom parser that only reads RMC ("Recommended Minimum") sentences from a UART and extracts the time from that (see
nmea.c
). -
The ATTiny13A lacks SPI and UART peripherals, so these are implemented in software.
Schematic and construction details can be found on this project's hackaday.io page.
The avr-gcc
toolchain is required to build, but there are no other external dependencies.
# Build
make
# Flash with programmer configured in Makefile
make flash
The simple test suite for NMEA RMC sentence decoding can be run manually with:
make test