NXP Semiconductors PCA8565 Initialization and setting of alarm and timer, Block Diagram PCF8563

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NXP Semiconductors	UM10301
	User Manual PCF85x3, PCA8565 and PCF2123, PCA2125

12. Initialization and setting of alarm and timer

Setting the clock is a straightforward procedure, setting first the mode and then the actual time. This example is for the PCF8563 and for reference its block diagram is given in Fig 10 which shows the registers and their addresses. The procedure for the other RTCs is similar but there are small differences in register structure and therefore the appropriate datasheet should be consulted first.

OSCI
	OSCILLATOR	DIVIDER		CLOCK OUT
	32.768 kHz	DIVIDER		CLOCK OUT
	32.768 kHz
OSCO
	MONITOR			CONTROL
	MONITOR		00	CONTROL_STATUS_1
			00	CONTROL_STATUS_1
			01	CONTROL_STATUS_2
			0D	CLKOUT_CONTROL
	POWER ON
	RESET
				TIME
			02	VL_SECONDS
			03	MINUTES
VDD			04	HOURS
VSS			05	DAYS
VSS			06	WEEKDAYS
			07	CENTURY_MONTHS
	WATCH		08	YEARS
	WATCH
	DOG
				ALARM FUNCTION
			09	MINUTE_ALARM
			0A	HOUR_ALARM
SDA	I2C-BUS		0B	DAY_ALARM
SCL	INTERFACE		0C	WEEKDAY_ALARM
				INTERRUPT
				TIMER FUNCTION
	PCF8563		0E	TIMER_CONTROL
	PCF8563		0F	TIMER
			0F	TIMER
				001aah658

CLKOUT

INT

Fig 10. Block Diagram PCF8563

Examples for initialisation and setting of time, alarm and timer are given below.

12.1 Initialization of the RTC and setting the time

Table 5 on the next page shows the sequence of commands to be sent to the RTC for initialization and setting the time.

In this example the time to be set is Friday, July 16 2008, 2:45 pm.

UM10301_1		© NXP B.V. 2008. All rights reserved.
User manual	Rev. 01 — 23 December 2008	26 of 52

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Contents Abstract Info Content KeywordsDocument information Revision history Contact informationNXP Semiconductors Rev Date DescriptionIntroduction Features Register overview PCF8563 Address Register name BitEvent counter mode ComparisonFeatures Comparison of six real time clocksVoltage-low detector Power-on reset PORPower-on reset Oscillator-stop detection OscillatorVoltage-low detection Pierce Oscillator equivalent diagram Overview of internal and external oscillator capacitorsOscillator frequency determining components UM10301 + C Typical values for crystal and surrounding capacitors Parameter Value Unit SourceUsing an external oscillator Oscillation allowanceCrystal and crystal selection Effect of temperature Modes which don’t work− f nom Capacitors and capacitor selection Accuracy Influences on time accuracy Oscillator tuning Oscillator tuning 10.1 PCF2123 Offset register Year and leap year tracking Century and leap year, Daylight Saving TimeCentury tracking Daylight Saving Time DSTBlock Diagram PCF8563 Initialization and setting of alarm and timerInitialization of the RTC and setting the time Binary BCD AlarmSetting the alarm Register Comments AddressAlarm function Register Setting the timerSetting the timer Backup power supply Lithium Primary cellsBackup circuit using primary lithium cell Backup circuit using secondary cell NiCd or NiMH NiCd and NiMH secondary batteries13.3 Capacitors Charging the backup capacitor 1N4148 Diode selectionSome suggestions for diode D1 BAS716 BAS116 BAV170PCB layout guidelines PCB layout proposal for PCF8563 using leaded components Partial circuit switch down Hints to keep power consumption low Protection diodes0007 8473 ⋅ C b Rpmax as a function of bus capacitanceApplication diagram 1, I2C-bus interface Application diagram 2, SPI interfaceTimer Source clock frequency Delay for n = First period inaccuracy when using the timerTimer delays General countdown timer behaviourFirst period delay for timer counter value n Timer source clock Minimum timer period Maximum timer periodTiming requirements for I2C read and write Block diagram I2C interface and Time counters I2C interfaceSequence of events example Read Troubleshooting Oscillator startup time Checking for oscillationNo communication via I2C-bus References Wrong time and date, wrong clock speedDisclaimers Legal informationDefinitions TrademarksContents