| ??? 11/21/05 05:25 Read: times |
#103933 - Suggestion may not work Responding to: ???'s previous message |
Erik Malund said:
assuming that by disconnected you mean removed
Taking the battery thrugh a divider to a port pin paralle with a zener will tell you, but load the battery. There are superlow quiscent current voltage regulator and if you use one of those to produce +5 for the uC to detect that should work. Erik Assuming the battery is conencted across JP5, placing a divider across it will not work, because, if the AC supply is present there will still be a voltage of the same order present, even if the battery is removed. If the AC supply is not present and the battery is removed, then the system will stop working anyway. One complicated possibility is to detect current flow through the battery with a low value 'shunt' resistor and amplify the signal. The charging voltage should be more than 12V, depending on type of battery, and there should always be a trickle of current into the battery allowing easy detection of current flow in both directions. This signal could also idicate the absence of the AC supply. Unsing the 'KISS' principle, the simplest of all, is to glue a small magnet to the battery and strategically place a reed switch connected to an I/O pin of the micro or even an interrupt. Removal of the battery will activate the reed etc. Tony |
| Topic | Author | Date |
| Battery Backup Trouble! | 01/01/70 00:00 | |
| a suggestion | 01/01/70 00:00 | |
| Suggestion may not work | 01/01/70 00:00 | |
| Simple, or simplistic? | 01/01/70 00:00 | |
| and it will state "no battery" when one | 01/01/70 00:00 | |
| Sorry | 01/01/70 00:00 | |
| Some more details please | 01/01/70 00:00 | |
| Use a proper Supervisor | 01/01/70 00:00 | |
| More Details! | 01/01/70 00:00 | |
| Put a CMOS transistor in series with | 01/01/70 00:00 | |
| Thanks | 01/01/70 00:00 | |
| What battery do you use? | 01/01/70 00:00 | |
| 8*1.5(NI-CD)! | 01/01/70 00:00 | |
| NI-CD is 1.2*N | 01/01/70 00:00 | |
| But when is full it is more than 1.2v | 01/01/70 00:00 | |
| Kai,when you say your idea? | 01/01/70 00:00 | |
| Now... | 01/01/70 00:00 | |
| Thanks Dear Kai, | 01/01/70 00:00 | |
| How it works... | 01/01/70 00:00 | |
| Your Time is for all of us,Kai | 01/01/70 00:00 | |
I would prefer the Pb-battery | 01/01/70 00:00 | |
| A/D? | 01/01/70 00:00 |