| ??? 02/13/05 09:18 Read: times |
#87254 - huh Responding to: ???'s previous message |
We looked at the 87C554 but the I/O should be the same in most devices. I looked again Erik is correct. The strong pullups are on for the full memory cycle. The strong pullups will be on for 2 clocks whenever the P2 SFR is updated to P2 if the previous value on the port was a zero (including a memory cycle that had a zero in this bit) and the current value is a one. The purpose of the strong pullup is to quickly change the pin from a zero to a one. If the previous value from the memory access was a one and the P2 data is now a one, there is no need for the strong pullup since the pin is already a one. P2 does not tri-state between memory address and P2 SFr data. MOVX @Ri has no effect on P2, so yes, I was talking about MOVX w/DPTR. |
| Topic | Author | Date |
| P2:R0 as memory pointer | 01/01/70 00:00 | |
| Read the cpu data! | 01/01/70 00:00 | |
| P2 readback | 01/01/70 00:00 | |
| Re | 01/01/70 00:00 | |
| Thank you all | 01/01/70 00:00 | |
| Interesting | 01/01/70 00:00 | |
| very well described | 01/01/70 00:00 | |
| This is NOT in the | 01/01/70 00:00 | |
| ch3 pg 6 | 01/01/70 00:00 | |
| none of them | 01/01/70 00:00 | |
| more | 01/01/70 00:00 | |
| An experiment - AT89C8252 | 01/01/70 00:00 | |
| not necessarily | 01/01/70 00:00 | |
| sure not necessarily | 01/01/70 00:00 | |
| talking about memory | 01/01/70 00:00 | |
| MOVX multiplexed with P2 SFR data | 01/01/70 00:00 | |
| Now I say: HUH | 01/01/70 00:00 | |
| huh | 01/01/70 00:00 | |
| Thank you | 01/01/70 00:00 | |
| what datasheet says | 01/01/70 00:00 | |
| I should've RTFM... :-) | 01/01/70 00:00 | |
| not too much logic | 01/01/70 00:00 | |
| sure | 01/01/70 00:00 | |
| The horses mouth | 01/01/70 00:00 | |
| horse is plural | 01/01/70 00:00 | |
| I'd be happy to ... | 01/01/70 00:00 | |
| can't find them | 01/01/70 00:00 | |
As you use to say :) | 01/01/70 00:00 | |
| another note | 01/01/70 00:00 |