| ??? 06/06/06 15:06 Read: times |
#117873 - No hardware knowledge Responding to: ???'s previous message |
Erik said:
do you have any hardware knowledge I have no theoritical hardware knowledge. But I have played around with a few non programmable chips like 74LS373 and 74LS138! I plan to learn only as things come in my way of developing my system, (a DAQ). Erik said: visualize a port pin as a "wired OR" let ys take 3 transistors and connect the collectors together. Then a resistor to +5. If ANY of these transistors is ON, the outputb is low, if all are off, the output is high. Got that,I can see from your analogy is that the pin will retain its value even if we try to change it externally. But still dont see if that will make the instructions
MOV P2,#1 ;writing HIGH to bit 0 of port2
MOV P2,#0 ;writing LOW to bit 0 of port2
serve my purpose or not? |
| 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 |