PCF2127AT/1 NXP [NXP Semiconductors], PCF2127AT/1 Datasheet - Page 56

• Manufacturer Part Number: PCF2127AT/1
• Description: Integrated RTC, TCXO and quartz crystal
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
PCF2127A_2
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. 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
SA
SA
currents may result.
Table 58.
b5
b5
Bit
7
6 to 5
4 to 0
1
1
b4
b4
0
0
b3
b3
0
1
addr 03h
addr 08h
Symbol
R/W
SA
RA
Command byte definition
b2
b2
0
0
b1
b1
1
0
All information provided in this document is subject to legal disclaimers.
b0
b0
1
0
b7
b7
03
08
0
0
Rev. 02 — 7 May 2010
b6
b6
1
0
seconds data 45
months data 11
b5
b5
0
0
Value
0
1
01
00h to 1Dh register address
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
04
09
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
05
0A
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