PCF8564A datasheet(23/59 Pages) NXP

23 / 59 page

PCA85063A

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Product data sheet

Rev. 4 — 30 March 2018

23 of 59

NXP Semiconductors

PCA85063A

Automotive Real-Time Clock/calendar with alarm function and I2C-bus

8.3.7 Register Years

[1]

Default value.

8.4 Setting and reading the time

Figure 12 shows the data flow and data dependencies starting from the 1 Hz clock tick.

During read/write operations, the time counting circuits (memory locations 04h through

0Ah) are blocked.

The blocking prevents

• Faulty reading of the clock and calendar during a carry condition

• Incrementing the time registers during the read cycle

After this read/write access is completed, the time circuit is released again and any

pending request to increment the time counters that occurred during the read/write access

is serviced. A maximum of 1 request can be stored; therefore, all accesses must be

completed within 1 second (see Figure 13).

Table 28.

Years - years register (0Ah) bit description

Bit

Symbol

Value

Place value Description

7 to 4

YEARS

0[1] to 9

ten’s place

actual year coded in BCD format

3to0

0[1] to 9

unit place

Fig 12. Data flow for the time function

PCF8564A Datasheet(PDF) 23 Page - NXP Semiconductors