| ??? 06/06/06 09:12 Read: times Msg Score: +1 +2 Good Question -1 Overrated |
#117839 - Help Understanding AT89C51 Datasheet |
Hello Guys,
As some of you might already know, I am a real newbie to electronics and 8051\52. I was reading the datasheet of AT89C51. And did not understand a few things. One is this: The Port 1 output buffers can sink/source four TTL inputs. Does this mean that that though there are 8 pins in a port only 4 pins can be used as inputs/outputs at a time? I am planning to use all 8 pins of Port2 as output. Will that be a problem? Two: When 1's are written to Port 1 pins they are pulled high by internal pullups and can be used as inputs. In that case if I send a 1 to an output pin, it becomes an input pin. Can I still write a zero to that pin and keep using it as output? |
| Topic | Author | Date |
| Help Understanding AT89C51 Datasheet | 01/01/70 00:00 | |
| logic gain and other | 01/01/70 00:00 | |
| Should I study more? | 01/01/70 00:00 | |
| do you have any hardware knowledge | 01/01/70 00:00 | |
| No hardware knowledge | 01/01/70 00:00 | |
| what purpose? | 01/01/70 00:00 | |
| Purpose | 01/01/70 00:00 | |
| many get confused by this | 01/01/70 00:00 | |
| Got it ! | 01/01/70 00:00 | |
| per-pin, per-port, and whole-chip limits | 01/01/70 00:00 | |
| strictly speaking... | 01/01/70 00:00 | |
| Slight oversimplification | 01/01/70 00:00 | |
| it used to be DC, now it is AC | 01/01/70 00:00 | |
"per pin" | 01/01/70 00:00 | |
| Good post! | 01/01/70 00:00 | |
| Excellent Community | 01/01/70 00:00 | |
| have you read "the bible" | 01/01/70 00:00 | |
| Yes, I have started | 01/01/70 00:00 |