pcf2127a NXP Semiconductors, pcf2127a Datasheet - Page 55

• Manufacturer Part Number: pcf2127a
• Description: Integrated Rtc, Tcxo And Quartz Crystal
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCF2127A_1
Product data sheet
Fig 36. SPI-bus write example
Fig 37. SPI-bus read example
SDA/CE
SDA/CE
address
address
counter
counter
In this example, the register Seconds is set to 45 seconds and the register Minutes to 10 minutes.
SDO
In this example, the registers Months and Years are read. In this example, pins SDI and SDO are not connected together. For
this configuration, it is important that pin SDI is never left floating. It must always be driven either HIGH or LOW. If pin SDI is left
open, high I
SCL
SCL
SDI
SDI
xx
xx
R/W
R/W
b7
b7
0
1
b6
b6
DD
0
0
currents may result.
Table 58.
b5
b5
Bit
7
6 to 5
4 to 0
1
1
b4
b4
0
0
addr 34
addr 34
b3
b3
0
0
Symbol
R/W
SA
RA
bin
bin
Command byte definition
b2
b2
0
0
b1
b1
1
1
b0
b0
0
0
b7
b7
Rev. 01 — 21 January 2010
02
02
0
0
b6
b6
1
0
seconds data 45
months data 11
b5
b5
0
0
Value
0
1
01
00h to 1Dh register address range
b4
b4
0
1
b3
b3
0
0
BCD
BCD
b2
b2
1
0
Description
data read or write selection
subaddress;
b1
b1
0
0
write data
read data
other codes will cause the device to ignore data
transfer
Integrated RTC, TCXO and quartz crystal
b0
b0
1
1
b7
b7
03
03
0
0
b6
b6
0
0
minutes data 10
b5
b5
years data 06
0
0
b4
b4
1
0
b3
b3
0
0
PCF2127A
BCD
BCD
b2
b2
0
1
© NXP B.V. 2010. All rights reserved.
b1
b1
0
1
b0
001aaj348
b0
001aaj349
0
0
04
09
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