Table 7-10. Real-Time Clock RTCxR Data Registers

Real-Time Clock x Holding Register

(RTC0R) R/W

(Address = 0x02)

 

 

 

(RTC1R)

(Address = 0x03)

 

 

 

(RTC2R)

(Address = 0x04)

 

 

 

(RTC3R)

(Address = 0x05)

 

 

 

(RTC4R)

(Address = 0x06)

 

 

 

(RTC5R)

(Address = 0x07)

Bit(s)

Value

 

Description

 

 

 

 

7:0

Read

The current value of the 48-bit RTC holding register is returned.

 

 

 

 

Write

Writing to the RTC0R transfers the current count of the RTC to six holding

 

registers while the RTC continues counting.

 

 

 

 

 

 

 

 

 

Table 7-11. Real-Time Clock Control Register (RTCCR adr = 0x01)

Bit(s)

Value

Description

 

 

 

 

 

Writing a 0x00 to the RTCCR has no effect on the RTC counter.

 

 

However, depending on what the previous command was, writing

 

 

a 0x00 may either

 

0x00

1. disable the byte increment function or

 

2. cancel the RTC reset command

 

 

 

 

If the 0xC0 command is followed by a 0x00 command, only the

 

 

byte increment function will be disabled. The RTC reset will still

7:0

 

take place.

 

 

0x40

Arm RTC for a reset with code 0x80 or reset and byte increment

 

 

function with code 0x0C0.

 

 

 

 

 

 

0x80

Resets all six bytes of the RTC counter to 0x00 if proceeded by

 

arm command 0x40.

 

 

 

 

 

 

 

Resets all six bytes of the RTC counter to 0x00 and enters byte

 

0xC0

increment mode—precede this command with 0x40 arm

 

 

command.

 

 

 

 

 

This bit combination must be used with every byte increment write

 

 

to increment clock(s) register corresponding to bit(s) set to "1".

7:6

01

Example: 01001101 increments registers: 0, 2,3. The byte

 

 

increment mode must be enabled. Storing 0x00 cancels the byte

 

 

increment mode.

 

 

 

5:0

0

No effect on the RTC counter.

 

 

1

Increment the corresponding byte of the RTC counter.

 

 

 

 

92

Rabbit 3000 Microprocessor

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Jameco Electronics 2000, 3000 manual Real-Time Clock RTCxR Data Registers, Real-Time Clock Control Register Rtccr adr =