C515C_9711 Datasheet, PDF (46/268 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

External Bus Interface
C515C
4.4 ALE, Address Latch Enable
The C515C allows to switch off the ALE output signal. If the internal ROM is used (EA=1) and ALE
is switched off by EALE=0, Then, ALE will only go active 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 the ALE generation is enabled.
Special Function Register SYSCON (Address B1H)
Reset Value C515C-8R : X010XX01B
Reset Value C515C-8E : X010X001B
Bit No. MSB
LSB
7
6
5
4
3
2
1
0
B1H
– PMOD EALE RMAP – _{CSWO XMAP1 XMAP0} SYSCON
The function of the shaded bit is not described in this section.
Bit
–
EALE
Function
Reserved bits for future use.
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.
Semiconductor Group
4-4
1997-11-01