TS80C51RA2 Atmel Corporation, TS80C51RA2 Datasheet - Page 49

• Manufacturer Part Number: TS80C51RA2
• Description: High Performance 8-bit Microcontroller
• Manufacturer: Atmel Corporation

Reduced EMI Mode
4188A–8051–10/02
The ALE signal is used to demultiplex address and data buses on port 0 when used with
external program or data memory. Nevertheless, during internal code execution, ALE
signal is still generated. In order to reduce EMI, ALE signal can be disabled by setting
AO bit.
The AO bit is located in AUXR register at bit location 0. As soon as AO is set, ALE is no
longer output but remains active during MOVX and MOVC instructions and external
fetches. During ALE disabling, ALE pin is weakly pulled high.
Table 29. AUXR Register
AUXR - Auxiliary Register (8Eh)
Reset Value = XXXX XX00b
Not bit addressable
Number
Bit
7
6
5
4
3
2
1
0
7
-
Mnemonic
EXTRAM
Bit
AO
6
-
-
-
-
-
-
-
Description
Reserved
The value read from this bit is indeterminate. Do not set this bit.
Reserved
The value read from this bit is indeterminate. Do not set this bit.
Reserved
The value read from this bit is indeterminate. Do not set this bit.
Reserved
The value read from this bit is indeterminate. Do not set this bit.
Reserved
The value read from this bit is indeterminate. Do not set this bit.
Reserved
The value read from this bit is indeterminate. Do not set this bit.
EXTRAM bit
See Table 5.
ALE Output bit
Clear to restore ALE operation during internal fetches.
Set to disable ALE operation during internal fetches.
5
-
4
-
3
-
2
-
TS8xC51Rx2
EXTRAM
1
AO
0
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