C508_01 Datasheet, PDF (46/267 Pages) Infineon Technologies AG – 8-Bit CMOS Microcontroller

C508
External Bus Interface
4.4
ALE, Address Latch Enable
The C508 allows the ALE output signal to be switched off. If the internal ROM is used
(EA = 1 and PC ≤ 7FFF_H) and ALE is switched off by EALE = 0, then, ALE will go active
only during external data memory accesses (MOVX instructions). If EA = 0, the ALE
generation is always enabled and the bit EALE has no effect.
After a hardware reset, ALE generation is enabled.
Special Function Register SYSCON (Address B1_H)
Reset Value: XX10XX01_B
Bit No. MSB
7
B1_H
–
6
5
4
3
– EALE RMAP –
LSB
2
1
0
– XMAP1 XMAP0 SYSCON
The shaded bits are not described in this section.
Bit
EALE
–
Function
Enable ALE output
EALE = 0: ALE generation is disabled; disables ALE signal
generation during internal code memory accesses
(EA = 1).
With EA = 1, ALE is automatically generated at MOVX
instructions.
EALE = 1: ALE generation is enabled.
If EA = 0, the ALE generation is always enabled and the bit EALE
has no effect on the ALE generation.
Reserved bits for future use. Read by CPU returns undefined
values.
User’s Manual
4-4
2001-05