NXP Semiconductors OM11059UL User manual

UM10699
User manual for SPI-bus RTC demoboard OM11059UL
Rev. 3 — 18 August 2020 User manual
Document information
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Keywords PCF85063BTL, OM11059UL, demoboard, how to get started, SPI-bus, RTC,
Real-Time Clock, tuning
Abstract User manual for the RTC SPI-bus demoboard OM11059UL which contains
PCF85063BTL

NXP Semiconductors UM10699
User manual for SPI-bus RTC demoboard OM11059UL
UM10699 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2020. All rights reserved.
User manual Rev. 3 — 18 August 2020
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Revision history
Rev Date Description
v.3 20200819 Added Section 6; changed "OM11059" to "OM11059UL" throughout
v.2 20150212 revised version
v.1 20130404 Initial version

NXP Semiconductors UM10699
User manual for SPI-bus RTC demoboard OM11059UL
UM10699 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2020. All rights reserved.
User manual Rev. 3 — 18 August 2020
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1 Introduction
The PCF85063x are a family of CMOS Real-Time Clocks (RTC) and calendar optimized
for low power consumption. Different features sets are available.
The OM11059UL is the ideal evaluation/demo board to use in the design phase of any
project, just power and SPI-bus must be hooked up.
A separate demoboard and a user manual are available for the I2C-bus RTCs
PCF85063AT:OM13515 and UM10788.
2 Key features
The RTC PCF85063BTL with SPI-bus is mounted together with a quartz crystal and the
blocking capacitor, buffering the supply voltage.
2.1 PCF85063BTL
The RTC PCF85063BTL is a Real-Time Clock with very small form factor, counting
seconds, minutes, hours, days, weekdays, months, and years.
Electronic oscillator tuning
RAM: 1 Byte
Package: HXSON10 package: 2.6 x 2.6 x 0.5 mm
Alarm control
Timer
Interrupt: every 30 s or 60 s, alarm, timer
Interface: SPI-bus, up to 8 MHz
Clock out: enabled by pin or by software

NXP Semiconductors UM10699
User manual for SPI-bus RTC demoboard OM11059UL
UM10699 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2020. All rights reserved.
User manual Rev. 3 — 18 August 2020
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Table 1. Block diagram of the PCF85063BTL RTC
3 Hardware set-up
3.1 General requirements for the RTC PCF85063BTL
The RTC circuit just requires one external part: a tuning fork quartz as resonator.
The oscillation capacitors are integrated and therefore there is no need for external
capacitors. The quartz crystal must be placed close to the RTC circuit, avoiding long lines
which may pick up noise. Avoid any tracks with high frequency signals (fast edges) close
to the RTC, quartz, or quartz interconnect.
The interface uses a three-line standard SPI protocol: chip enable, serial clock, serial
data I/O operating up to 8 MHz.
Supply voltage: The RTC is specified from 1.8 V to 5.5 V. The RTC, excluding the SPI-
bus interface, is however operating down to a lower voltage. It is recommended to have a
decoupling capacitor on the VDD-VSS rails close by.
Due to the low power consumption of below 1 μW, no precautions for heat dissipations
are required.
CLKOUT can be used to measure the frequency or be used as reference for frequency
generation with a PLL.

NXP Semiconductors UM10699
User manual for SPI-bus RTC demoboard OM11059UL
UM10699 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2020. All rights reserved.
User manual Rev. 3 — 18 August 2020
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Table 2. Interfacing to microcontroller

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User manual for SPI-bus RTC demoboard OM11059UL
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3.2 Demo board OM11059UL
Table 3. Picture and layout of demo bard OM11059UL
The OM11059UL allows to easily demonstrate operation of the PCF85063BTL with SPI-
bus interface. No need to solder the tiny package to a breadboard 100 mil connector for
straight forward connections.

NXP Semiconductors UM10699
User manual for SPI-bus RTC demoboard OM11059UL
UM10699 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2020. All rights reserved.
User manual Rev. 3 — 18 August 2020
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There are quartzes on the market with different load capacitance CL. 12.5 pF is most
common, 7 pF offers however lower power consumption. By default a quartz with 7 pF is
mounted. Additional landing pads are available on the board to take a quartz in a tubular
package.
Straight forward interfacing:
- Connect supply voltage (e.g. 3.3 V): VSS to pin 1, VDD to pin 2 - Connect SPI-bus: CE
to pin 4, SCL to pin 3, SDI/O to pin 7 - Communicate to the RTC
Table 4. OM11059UL block diagram

NXP Semiconductors UM10699
User manual for SPI-bus RTC demoboard OM11059UL
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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.

NXP Semiconductors UM10699
User manual for SPI-bus RTC demoboard OM11059UL
UM10699 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2020. All rights reserved.
User manual Rev. 3 — 18 August 2020
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4.2 System testing
There is a fast mode facility to test the functionality of the RTC; it can be activated by
setting the EXT_TEST bit in the Control_1 word.
The RTC PCF85063BTL has a frequency tuning facility; its operation is explained in
section 5.
The RTC can stay switched on all the time. There is no need to restart or reset the clock.
4.3 Software instructions for setting the clock
4.3.1 Setting the time
Table 6. Setting the clock to 3.45 pm February 14, 2015
Name Address Setting
CE chip enable
Register address 0000 0000 address pointer to status word 0
0000 0011 set 12 hour mode and select option for
12.5 pF quartz
Status word 0
0000 0010 set 12 hour mode and select option for
7 pF quartz
CE chip disable
CE chip enable
Register address 0000 0100 address pointer to seconds register
Seconds 0000 0000 0 seconds (clock integrity ok → MSB
OS = 0)
Minutes 0100 0101 45 min
Hours 0010 0011 PM, 3 (clock integrity ok → OS = 0)
Days 0001 0100 14th day of month
Weekdays 0000 0110 Saturday (6th day of the week)
Month 0000 0010 February
Year 0001 0101 (20)15
CE chip disable
4.3.2 Reading the clock
Table 7. Reading the clock (2 minutes after writing)
Name Address Setting
CE chip enable
Register address 0000 0100 address pointer to seconds (R/W;
bit = 1)
Read register 4, seconds . . . . . . . . e.g. 56 Seconds, (clock integrity ok →
OS = 0)
Minutes . . . . . . . . e.g. 46 (minutes)

NXP Semiconductors UM10699
User manual for SPI-bus RTC demoboard OM11059UL
UM10699 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2020. All rights reserved.
User manual Rev. 3 — 18 August 2020
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Name Address Setting
Hours . . . . . . . . e.g. 03 (PM 03h)
Days . . . . . . . . e.g. 14 (14th)
Weekdays . . . . . . . . e.g. 06 (Saturday)
Month . . . . . . . . e.g. 02 (February)
Year . . . . . . . . e.g. 15 (20)15
CE chip disable
5 RTC tuning
5.1 Frequency tuning
The 32 kHz quartzes are typically sold with a tolerance at room temperature of either
±10 ppm or ±20 ppm. 11.5 ppm corresponds to 1 s/day.
The quartzes require a characteristic load capacity of either 7 pF or 12.5 pF. Oscillators
utilizing 7 pF quartzes feature slightly lower power consumption, where the quartzes
of 12.5 pF have largest production quantities. The tracks between quartz and RTC
represent also some parasitic capacitances and must be kept short.
The PCF85063 has a tuning facility where above tolerances can be compensated.
Tuning procedure:
•Measure the 32xxx Hz (f) signal at the CLKOUT pin.
•The offset is calculated in ppm as: Δf[ppm] = 106 × (f - 32768) / 32768
•Consult the offset table in the data sheet. Take the correction value and write it into the
register 02h.
•The correction is done by means of inhibition or addition: the oscillator runs at constant
speed, then every 2 hours (mode 0) 1 second is corrected to by making it shorter or
longer. This is not easily visible at the CLKOUT.
•Corrections can also be applied every 4 minutes by using mode 1. This mode will
consume slightly more power.
The 32 kHz quartzes are of the type tuning fork and feature a parabolic frequency
response over temperature. When the application is dominantly used over a limited
temperature range, it is often helpful to tune the frequency to be slightly higher at the
turn-over point. The error around 25 °C (clock goes too fast) is then compensated during
the time when temperature is lower or higher. For example, for operation between 5 °C
and 45 °C, tune the clock 8 ppm faster than the value for 25 °C would be. (Fig 6.)