| ??? 08/21/05 14:29 Read: times |
#99775 - Pull up P0 and use 4081 Responding to: ???'s previous message |
Russell Bull said:
Since there are leds involved, trying to recover logic levels from the led drive circuit may be a little more difficult. I suggest you calculate the voltages to be expected where you are sampling the 7segment. The display is most likely multiplexed - how do you decode the multiplexing? The seven segment data is from P0 of 89C51 directly connected to all the data line of the six 7 Seg Led display. Each 7 segment is alternatively switched on and off using P2 pins through a transistor. I think i should be able to decode all the data without disturbing the unit usng 4081 and gates. So the exact voltage level should not be a big courcern except for P0 port there i have to use a pull up but the value i am not sure may be 10k. |
| Topic | Author | Date |
| 7 segent data bus tracker | 01/01/70 00:00 | |
| Logic levels | 01/01/70 00:00 | |
| Pull up P0 and use 4081 | 01/01/70 00:00 | |
| I don't think you understand the issue | 01/01/70 00:00 | |
| logic o | 01/01/70 00:00 | |
| required steps skipped | 01/01/70 00:00 | |
| analog voltages | 01/01/70 00:00 | |
Harald Erik | 01/01/70 00:00 |