| ??? 04/21/11 02:49 Read: times |
#181958 - Reset Circuitry for 80C535 Responding to: ???'s previous message |
Erik and all,
Of course I need to test chips with better Reset circuitry... I regard the use of a Reset Generator chip to properly initiate a reset pulse to the 80C535 very important. By chance I have got a small CPU Card for a Fire Alarm Panel, which also employs an 80C535. I found that it also contained a small Reset circuitry for the 80C535 CPU. I also found that Port 0 and 2 are connected directly to HC573 and memory chips which eliminate the open-collector issue as Erik had said. I want to attach the Reset schematic here, but I don't know how to do it. Please advise. Although it didn't use a Reset Generator chip (maybe because it was not yet available, because the card was manufactured in 1990s) I build this circuit yesterday afternoon and connected it to my 80C535 development board. Afterwards, I connected the board to PC running Hyperterminal, and press Enter. It worked! I pressed "?" for help, and it responsed greatly too, and displayed the Help Screen neatly. But after 3 commands, it stop working. I put off the power to the board, and then put it on again, but it could not response again ever since. The Reset circuitry seems to be very critical so I decided to build a Reset Generator IC for the board. This morning I tried the board again, and it worked until 4 commands and stop again. I think that it is not too easy to obtain a Reset Generator IC here at our local stores, so I maybe need several days to find it. If it also fail, I would like to consider examining the code. |
| Topic | Author | Date |
| Is 80C535 Compatible with 80C31? | 01/01/70 00:00 | |
| do not use pin numbers | 01/01/70 00:00 | |
| Supervisor Chip | 01/01/70 00:00 | |
| you say you want to test chips | 01/01/70 00:00 | |
| Reset Circuitry for 80C535 | 01/01/70 00:00 | |
| Timing | 01/01/70 00:00 | |
| probably because ... | 01/01/70 00:00 | |
| Supervisor/Watchdog Timer chip | 01/01/70 00:00 | |
| No timer needed to kick watchdog | 01/01/70 00:00 | |
| The internal Watchdog Timer | 01/01/70 00:00 | |
| good choice | 01/01/70 00:00 | |
| NE555 | 01/01/70 00:00 | |
| 8051 and 555 reset | 01/01/70 00:00 | |
| 555 Reset circuitry | 01/01/70 00:00 | |
| bad choice | 01/01/70 00:00 | |
| Reset Supervisor | 01/01/70 00:00 | |
| there are other possibilities | 01/01/70 00:00 | |
Other source | 01/01/70 00:00 | |
| did the datasheet not say so? | 01/01/70 00:00 | |
| It says so | 01/01/70 00:00 | |
| would it not be a good idea to do so before ... | 01/01/70 00:00 | |
| explain a bit about the nessecity of Supervisor Chip | 01/01/70 00:00 |