C868_02 Datasheet, PDF (29/244 Pages) Infineon Technologies AG – 8 - Bit CMOS Microcontroller

C868
Memory Organization
3.3.2 Chip Modes
The various chip modes supported are shown in Figure 3-2.
Normal
Mode
Bootstrap
Mode
Normal
XRAM
Mode
Hardware
Software
Bootstrap
XRAM
Mode
Figure 3-2 Entry and exit of Chip Modes
A valid hardware reset would, of course, override any of the above entry or exit
procedures.
Table 3-1 Hardware and Software Selection of Chipmodes
Operating Mode
(Chipmode)
Normal Mode
Normal XRAM Mode
Hardware Selection
ALE/BSL pin = high
RESET rising edge
Not possible
Software Selection
ALE/BSL = don’t care;
setting bits BSLEN, SWAP = 0,0;
execute unlocking sequence
setting bits BSLEN,SWAP = 0,1;
execute unlocking sequence
Bootstrap XRAM Mode Not possible
setting bits BSLEN,SWAP = 1,1;
execute unlocking sequence
Bootstrap Mode
ALE/BSL pin = low
RESET rising edge
ALE/BSL = don’t care;
setting bits BSLEN, SWAP = 1,0;
execute unlocking sequence
User’s Manual
3-5
V 0.4, 2002-01