| ??? 12/20/04 15:47 Read: times |
#83525 - blow it Responding to: ???'s previous message |
but there is something that makes me wrong , why whenever i write 0's to the port and disable the pullups ,the inputs are working OK !
I saved the schematic and read the saved copy. If you write 0 to a port pin and connect it directly to 5V (through a key) that pin is blown. Also, if a good port pin is set to 0, nothing can make you read a '1'. So, based on the above: What you state is impossible unless the output transistor on that pin is burned off and nothing else happened to the port. Double check your statement (writing zero and connecting +5 is igniting a fuse). First: rework the keys to standard (safe) configuration which is pullup resistor (4k7 - 10k to Vcc) and switch between pin and ground. Why, when what you have "works"? because the switch to +5 may make any program error or runaway blow the chip. Second: take a break, then analyze what you do in a non-hurried way. So far you probably have managed to blow your uC by trying dramatic measures. Anyone I know make more mistakes when hurried than when not. Erik |
| Topic | Author | Date |
| invalid voltage on a pulled up/down Port | 01/01/70 00:00 | |
| replace s with c | 01/01/70 00:00 | |
| Thats not the solution. | 01/01/70 00:00 | |
| please follow the main problem | 01/01/70 00:00 | |
| and some news | 01/01/70 00:00 | |
| s51 is good | 01/01/70 00:00 | |
| Pullup/down | 01/01/70 00:00 | |
| Sorry for Echo. | 01/01/70 00:00 | |
| pull up/downs | 01/01/70 00:00 | |
| pullup+pulldown = potential-divider? | 01/01/70 00:00 | |
| Potential, potential divider? | 01/01/70 00:00 | |
| potential divider / where wires go | 01/01/70 00:00 | |
| blow it | 01/01/70 00:00 | |
| don't blowed it (atleast not untill now) | 01/01/70 00:00 | |
| where does the wires go | 01/01/70 00:00 | |
| To Erik and others | 01/01/70 00:00 | |
| This will not work with 'C51s | 01/01/70 00:00 | |
| Exactly | 01/01/70 00:00 | |
| just got the point :) | 01/01/70 00:00 | |
| And finally the problem solved! | 01/01/70 00:00 | |
| I meant ++hundreds of microampere++ | 01/01/70 00:00 | |
| Wrong question ! | 01/01/70 00:00 | |
| Negative Logic? | 01/01/70 00:00 | |
Yes, negative logic! | 01/01/70 00:00 |