| ??? 05/02/05 19:19 Read: times |
#92750 - caveat Responding to: ???'s previous message |
The caveat is (besides you need to build the reset circuit yourself), that the backup source must keep the processor running at least for a while when there is no mains power (and the mains caps are already drained).
We made the error of using a 2.4V NiCd for backup (2V is enough for the RAM). On spurious resets (noise) the mcu attempted to start, but failed (AT89C2051, needed more to run) and lost the RAM content. Today I like to use a serial FRAM (Ramtron) for backup of often changing variables. I wouldn't believe to the "store to EEPROM while power is dying" method, or, better, I think there might caveats in that method, too (although I never tried that, I admit). Jan Waclawek |
| Topic | Author | Date |
| Troubles in POWER DOWN mode | 01/01/70 00:00 | |
| what's exactly the problem? | 01/01/70 00:00 | |
| the problem... | 01/01/70 00:00 | |
| that's bad... | 01/01/70 00:00 | |
| you are right... | 01/01/70 00:00 | |
| the problem | 01/01/70 00:00 | |
| A possible solution? | 01/01/70 00:00 | |
| on chip permanent storage | 01/01/70 00:00 | |
| caveat | 01/01/70 00:00 | |
| no caveat when done right | 01/01/70 00:00 | |
| 79 ? | 01/01/70 00:00 | |
| oh well | 01/01/70 00:00 | |
| caveat | 01/01/70 00:00 | |
| non-caveats | 01/01/70 00:00 | |
| "1" when v.supervisor is not powered | 01/01/70 00:00 | |
| use open pin | 01/01/70 00:00 | |
| ideas | 01/01/70 00:00 | |
| your idea... | 01/01/70 00:00 | |
| it seems to me,it is working... | 01/01/70 00:00 | |
please do not | 01/01/70 00:00 | |
| I had an idea... | 01/01/70 00:00 | |
| i tried this... | 01/01/70 00:00 | |
| wow that's bad | 01/01/70 00:00 | |
| i tried this... | 01/01/70 00:00 |