NXP Semiconductors
PCF8523
Real-Time Clock (RTC) and calendar
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Fig 18. Offset calibration calculation workflow
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8.9 Timer function
The PCF8523 has three timers:
• Timer A can be used as a watchdog timer or a countdown timer (see Section 8.9.2). It
can be configured by using TAC[1:0] in the Tmr_CLKOUT_ctrl register (0Fh)
• Timer B can be used as a countdown timer (see Section 8.9.3). It can be configured
by using TBC in the Tmr_CLKOUT_ctrl register (0Fh)
• Second interrupt timer is used to generate an interrupt once per second (see
Section 8.9.4)
Timer A and timer B both have five selectable source clocks allowing for countdown
periods from less than 1 ms to 255 h. To control the timer functions and timer output, the
registers 01h, 0Fh, 10h, 11h, 12h, and 13h are used.
PCF8523
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 7 — 28 April 2015
© NXP Semiconductors N.V. 2015. All rights reserved.
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