NXP Semiconductors
UM10699
User manual for SPI-bus RTC demoboard OM11059UL
UM10699
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User manual
Rev. 3 — 18 August 2020
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Table 5. OM11059UL schematics
4 Software set-up
4.1 Functionality
The RTC PCF85063BTL is controlled via standard SPI-bus interface. Common SPI
protocol applies.
Theoretically there is no lower speed limit, however a read or write access to the RTC
must be finalized within one second after initiating it, otherwise time counter increments
could be lost. During access, the time registers of the RTC are frozen and after the read
or write sequence is completed, a seconds increment is executed if required.
The clock tracks the actual time from seconds to year. It must be initially set to the
correct time of the actual time zone. The days per month and leap year are corrected
automatically. Leap years are assumed whenever the year is dividable by 4.
The RTC can be programmed to generate an interrupt every 30 seconds or every
60 seconds.
At address byte 03h is a general purpose RAM byte to store temporary information.