DCF77 atomic clock using 1602 type LCD, sets MCU RTC and goes into Deep Sleep, waking every second to update LCD time. Re acquires DCF time every 24 hours, tests for available signal and indicates DCF pulse width in millisecond's. Time zone can be changed at the beginning of the code. If no signal detected, the program sleeps updating the display with the current RTC time then try's again in 1 hour. The RTC will remain accurate until power is cycled where it will reset the RTC registers. Hard reset will not effect RTC registers. Tested using a project MCU board, MCU Deep Sleep power is 3uA, 1602 LCD is 900uA. Wake up takes around 12mS to update display time every second. The current FRDM board has a PCB track issue that does not allow the power to be monitored.

Dependencies:   TextLCD WakeUp mbed


RevisionDateWhoCommit message
0:f40db885ccfb 2014-02-26 star297 Initial version 1.0 default tip