pcf2127a NXP Semiconductors, pcf2127a Datasheet - Page 15

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

NXP Semiconductors
PCF2127A_1
Product data sheet
8.5.5.1
8.5.1 Register RAM_addr_MSB
8.5.2 Register RAM_addr_LSB
8.5.3 Register RAM_wrt_cmd
8.5.4 Register RAM_rd_cmd
8.5.5 Operation examples
8.5 General purpose 512 bytes static RAM
The PCF2127A contains a general purpose 512 bytes static RAM. This integrated SRAM
is battery backed and can therefore be used to store data which is essential for the
application to survive a power outage.
9 bits, RA[8:0], define the RAM address pointer in registers RAM_addr_MSB and
RAM_addr_LSB. The register address pointer increments after each read or write
automatically up to 1Bh and then wraps around to address 00h (see
Data is transferred to or from the RAM via the interface. To write to the RAM, the register
RAM_wrt_cmd, to read from the RAM the register RAM_rd_cmd must be addressed
explicitly.
Table 13.
Table 14.
Table 15.
Table 16.
Writing to the RAM
Bit
7 to 1
1
Bit
7 to 0
Bit
7 to 0
Bit
7 to 0
1. Set RAM address:
2. Send RAM write command:
– Select register RAM_addr_MSB (send address 1Ah).
– Set value for bit RA8 (data byte of register 1Ah);
– Set value for array RA[7:0] (data byte of register 1Bh).
– Select register RAM_wrt_cmd (send address 1Ch).
note: register address will be incremented automatically to 1Bh.
RAM_addr_MSB - RAM address MSB register (address 1Ah) bit description
RAM_addr_LSB - RAM address LSB register (address 1Bh) bit description
RAM_wrt_cmd - RAM write command register (address 1Ch) bit description
RAM_rd_cmd - RAM read command register (address 1Dh) bit description
Symbol
-
RA8
Symbol
RA[7:0]
Symbol
Symbol
RA[7:0]
RA[7:0]
Rev. 01 — 21 January 2010
Description
unused
RAM address, MSB (9
Description
RAM address, LSB (1
Description
data to be written into RAM
Description
data to be read from RAM
Integrated RTC, TCXO and quartz crystal
st
th
to 8
bit)
th
bit)
PCF2127A
Figure
© NXP B.V. 2010. All rights reserved.
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