PCF2129AT NXP [NXP Semiconductors], PCF2129AT Datasheet - Page 46

• Manufacturer Part Number: PCF2129AT
• Description: Integrated RTC, TCXO and quartz crystal
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
PCF2129A_1
Product data sheet
Fig 29. SPI-bus write example
Fig 30. 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. The 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 49.
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
02
02
Rev. 01 — 13 January 2010
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
PCF2129A
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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