Functional description – Rainbow Electronics LM81 User Manual
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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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