| ??? 05/28/05 18:02 Read: times |
#94055 - Confustion maybe? Responding to: ???'s previous message |
Michael Karas said:
Some designers may try to promote the idea that the internal pullup resistor in the 8051 quasi-bidirectional pin architecture is enough to ensure the high state of the OFF opto-coupler output but I have two reasons for recommending otherwise.
Hi Michael, Thanks very much for this extended explanation. However, allow me to ask if your explanation is valid also for the PCF8574? In your explanation, you were always referring to the IO pins of the 8051, but I'm using the IO pins of the PCF8574. Is the explanation you gave for the 8051 still/also valid for the PCF8574 IO expander? Best rgds, --Geert |
| Topic | Author | Date |
| CNX83: application examples? | 01/01/70 00:00 | |
| HOW | 01/01/70 00:00 | |
| did you find some in a drawer | 01/01/70 00:00 | |
| I know they're quite old... | 01/01/70 00:00 | |
| Better | 01/01/70 00:00 | |
| Schmitt Trigger | 01/01/70 00:00 | |
| nothing wrong - but | 01/01/70 00:00 | |
| Not working, Erik | 01/01/70 00:00 | |
| Pullup Or Not | 01/01/70 00:00 | |
| Additional Comment on Rise Time | 01/01/70 00:00 | |
| Confustion maybe? | 01/01/70 00:00 | |
| Yes, you need on PCF8574 | 01/01/70 00:00 | |
| No hijacking at all!!! ;-) | 01/01/70 00:00 | |
| Walks like a duck? Quacks like a duck? | 01/01/70 00:00 | |
| Yes, I do have quite a few ducks... | 01/01/70 00:00 | |
| Correct? | 01/01/70 00:00 | |
| Correct !! | 01/01/70 00:00 | |
| you must have edited | 01/01/70 00:00 | |
| I didn't do anything... | 01/01/70 00:00 | |
I do not know | 01/01/70 00:00 |