| ??? 06/12/05 10:47 Read: times |
#94716 - my first suggestion.... Responding to: ???'s previous message |
My first sugestion is that in your code you deselect the previously active device BEFORE selecting the next device. You did it the opposite order in the code snippets you showed. By using your method there is a several bus cycle long period of time that you have both the EEPROM and the 8255 selected. This may be the root of your problem.....especially if your trying to operate the 8255 with the Write strobe pulse not carefully controlled.
Michael Karas |
| Topic | Author | Date |
| external memory access problem | 01/01/70 00:00 | |
| my first suggestion.... | 01/01/70 00:00 | |
| actually i tried in single instruction | 01/01/70 00:00 | |
| more | 01/01/70 00:00 | |
| Relic Chips Are Slow | 01/01/70 00:00 | |
| Memory Map IT !! | 01/01/70 00:00 | |
| and then you may get others | 01/01/70 00:00 | |
| Such AS ?? | 01/01/70 00:00 | |
| with the '51 | 01/01/70 00:00 | |
| 8085/805x <=>8255 | 01/01/70 00:00 | |
| to slow, too low | 01/01/70 00:00 | |
really need more info to be helpful | 01/01/70 00:00 | |
| Query | 01/01/70 00:00 | |
| re query | 01/01/70 00:00 |