| ??? 02/24/07 03:15 Read: times |
#133613 - Just to see, whether there's an internal damage Responding to: ???'s previous message |
Padmanabhan said:
because there is already an interal pullup resistor in the port..
wht difference would it make if i connect the 100k resistor.. If you damage the port circuitry, so that it emits all the time 0s, then you may have an impedance of tens or hundreds of Ohms to ground, via the shorted NMOS. If you now connect 5V directly to the damaged P3.0, then Vcc might be stronger than the short circuit and could force logic high state. But the less stronger output of ADC can still be shorted to ground. That's why I asked you, whether a voltmeter will show 0V at P3.0, if no additional load (ADC) is connected to it and 1s has been written to P3.0. Kai |
| Topic | Author | Date |
| a peculiar problem | 01/01/70 00:00 | |
| ? | 01/01/70 00:00 | |
| To what port pin do you connect the MSB? | 01/01/70 00:00 | |
| and a schematic | 01/01/70 00:00 | |
| 1s written to P3.0? | 01/01/70 00:00 | |
| Modify your user profile | 01/01/70 00:00 | |
| yes | 01/01/70 00:00 | |
| What shows the voltmeter,... | 01/01/70 00:00 | |
| multimeter | 01/01/70 00:00 | |
| So you have 0V all the time at P3.0,... | 01/01/70 00:00 | |
| wen i connect p3.0.. | 01/01/70 00:00 | |
| Yes, but what if the ADC isn't connected? | 01/01/70 00:00 | |
| no no .. | 01/01/70 00:00 | |
| Ok, different try... | 01/01/70 00:00 | |
| precisely.. | 01/01/70 00:00 | |
| Does it also work, ... | 01/01/70 00:00 | |
| i didnt try it.. | 01/01/70 00:00 | |
| Just to see, whether there's an internal damage | 01/01/70 00:00 | |
i never thought of that .. | 01/01/70 00:00 | |
| modified | 01/01/70 00:00 | |
| Thanks, please publish your schematic again... | 01/01/70 00:00 | |
| sure | 01/01/70 00:00 | |
| Thanks! | 01/01/70 00:00 |