MOD-RTC REAL TIME CLOCK INTERFACE BOARD WITH PCF8563 AND UEXT
MOD-RTC add real time clock feature to boards with UEXT connector . The time keeping accuracy is tuned to 2 seconds per day, more accurate tuning is possible by adjusting the internal PCF8563 registers.
FEATURES:
- PCF8563 Real time clock
- Lithium 3V battery connector
- UEXT connector
- FR-4, 1.5 mm, soldermask, component print
- Dimensions: 40x19mm (1.57 x 0.75")
DOCUMENTS:
MOD-RTC.pdf user manual
HARDWARE:
MOD-RTC schematic
SOFTWARE:
DUINOMITE firmware can use MOD-RTC with SETUP command
DOCUMENTS:
This document has some PCF8563 calibration tips:
http://www.nxp.com/documents/application_note/AN10652.pdf
From Ernie (KSD Forum)
Putting a trim cap on the OSCI pin, as seen in fig 3 of the initial calibration section, seemed the easiest thing to adjust. People forget that watch crystals are calibrated at 25C to allow for body heat. It's unlikely your room temp will be at 25C all day, so you will get drift.
The main thing is the drift caused by temperature is well known and documented, so your software can compensate for it with an external temperature sensor, a little bit of effort.
