TS87C51RD2 ATMEL Corporation, TS87C51RD2 Datasheet - Page 50

• Manufacturer Part Number: TS87C51RD2
• Description: (TS8xC51Rx2) High Performance 8-bit Microcontroller
• Manufacturer: ATMEL Corporation

7.1
50
Reduced EMI Mode
AT/TS8xC51Rx2
The ALE signal is used to demultiplex address and data buses on port 0 when used with exter-
nal 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 7-2.
Reset Value = XXXX XX00b
Not bit addressable
Number
Bit
7
6
5
4
3
2
1
0
7
-
Mnemonic
EXTRAM
AUXR Register
AUXR - Auxiliary Register (8Eh)
AO
Bit
-
-
-
-
-
-
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 6-1.
ALE Output bit
Clear to restore ALE operation during internal fetches.
Set to disable ALE operation during internal fetches.
5
-
4
-
3
-
2
-
EXTRAM
1
4188E–8051–08/06
AO
0