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Functional description – Rainbow Electronics LM81 User Manual

Page 25

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Functional Description

(Continued)

13.0 REGISTERS AND RAM

13.1 Address Register

The main register is the ADDRESS Register. The bit designations are as follows:

Bit

Name

Read/

Write

Description

7-0

Address
Pointer

Write

Address of RAM and Registers. See the tables below for detail.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Address Pointer (Power On default 00h)

A7

A6

A5

A4

A3

A2

A1

A0

13.2 Address Pointer Index (A7–A0)

Registers and RAM

A6–A0 in

Hex

Power On Value of

Registers:

Notes

<

7:0

>

in Binary

Configuration Register

40h

0000 1000

Interrupt Status Register 1

41h

0000 0000

Interrupt Status Register 2

42h

0000 0000

Interrupt Mask Register 1

43h

0000 0000

Interrupt Mask Register 2

44h

0000 0000

CI Clear Register

46h

0000 0000

VID/Fan Divisor Register

47h

<

7:4

>

= 0101;

<

3:0

>

= VID3–VID0

Serial Bus Address Register

48h

<

7:2

>

=0010 11;

<

1:0

>

=(A1)(A0)

VID4 Register

49h

<

7:1

>

=1000 000;

<

0

>

=VID4

Temperature Configuration
Register

4Bh

0000 0001

Extended Mode Register 1

4Ch

0100 0100

Extended Mode Register 2

4Dh

0000 0000

Value RAM

19h–3Dh

Address 19h default=1111 1111

Company ID

3Eh

0000 0001

This default designates National
Semiconductor.

Stepping

3Fh

0000 0011

Revisions of this device will start with 1 and
increment by one.

LM81

www.national.com

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