MCP795W21 datasheet(7/54 Pages) MICROCHIP

7 / 54 page

 2011-2012 Microchip Technology Inc.

Preliminary

DS22280C-page 7

MCP795W1X/MCP795W2X

2.11

RTCC Memory Map

The RTCC registers are contained in addresses 0x00h-

0x1fh. 64 bytes of user-accessable SRAM are located

in the address range 0x20-0x5f. The SRAM memory is

a separate block from the RTCC control and Configura-

tion registers. All SRAM locations are battery-backed-

up during a VCC power fail. Unused locations are not

accessible.

• Addresses 0x00h-0x07h are the RTCC Time and

Date registers. These are read/write registers.

Care must be taken when writing to these

registers with the oscillator running.

• Incorrect data can appear in the Time and Date

registers if a write is attempted during the time

frame where these internal registers are being

incremented. The user can minimize the

likelihood of data corruption by ensuring that any

writes to the Time and Date registers occur before

the contents of the second register reach a value

of 0x59H.

• Addresses 0x08h-0x0Bh are the device Configu-

ration, Calibration, Watchdog Configuration and

Event Detect Configuration registers.

• Addresses 0x0ch-0x11h are the Alarm 0 registers.

These are used to set up the Alarm 0, the

interrupt pin and the Alarm 0 compare.

• Addresses 0x12h-0x17h are the Alarm 1

registers. These are used to set up the Alarm 1,

the interrupt pin and the Alarm 1 compare, Alarm

1 offers a enhanced resolution of tenth and

hundredths of seconds.

• Addresses 0x18h-0x1Fh are used for the power-

down and power-up time-stamp feature. The

detailed memory map is shown in Table 4-1. No

error checking is provided when loading Time and

Date registers.

FIGURE 2-2:

MEMORY MAP

0x00

0x07

Time and Date

Configuration and Calibration

Alarm 0

Alarm 1

Time-Stamp

SRAM (64 Bytes)

0x09

0x0B

0x0C

0x11

0x12

0x17

0x18

0x1F

0x20

0x5F

0x00

EEPROM

Memory

0x00

0x07

0x08

0x0F

RTCC Register/SRAM

EEPROM

Unique ID Location 2

Unique ID Location 1

EUI-48/64

Unique ID

0xFF

Note: 1K EEPROM Max address is 0x7F.

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