| ??? 12/20/04 09:07 Read: times |
#83498 - pullup+pulldown = potential-divider? Responding to: ???'s previous message |
whenever the AT89S51 is inserted P1.2,p1.3,p1.4 doesn't funtion properly as inputs,considering that the Push Buttons are pulled down ,so every time i press a button i should get high (+5) and when release them i should read GND (0v) I don't think so: P1 has internal pullups; so, when you release the switch, you have a potential divider formed by the internal pullup and your external pull-down the problem is when i release i get 2.3v-2.6v This doesn't sound unreasonable due to the potential-divider action above? |
| 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 |