??? 10/28/08 09:56 Read: times |
#159395 - naaaah... see bible Responding to: ???'s previous message |
Russell Bull said:
P0 and P2 contents will be related to the previous memory accces. After an external memory cycle, P0 is set to 0FFh (i.e. all pins floating - it's an open collector in that moment), and P2 regains its previous state (as having been written to the P2 SFR). Russell said: Yes, if the corresponding bits in P3 SFR are 1.
/WR & /RD will be high. With such a "mixed" mode, while possible, a mild caveat also might be, that while in the "true" external memory cycles both P2 and P0 are driven strongly to both 0 and 1; in the "port mode" P0 is open collector only, and P2 has that intel-ish quasi-bidirectional property. JW |
Topic | Author | Date |
is it possible to mix direct connect & mem. mapped | 01/01/70 00:00 | |
Probably,,, | 01/01/70 00:00 | |
naaaah... see bible | 01/01/70 00:00 | |
If your code is internal ... | 01/01/70 00:00 | |
It seems feasible... | 01/01/70 00:00 | |
I wouldn't presume to tell you what to do ... | 01/01/70 00:00 | |
ALE off SFR | 01/01/70 00:00 | |
I don't know what YOUR MCU does, but ...![]() | 01/01/70 00:00 |