| ??? 01/07/09 22:21 Modified: 01/07/09 22:25 Read: times |
#161367 - How stabile is your signal source? Responding to: ???'s previous message |
Are you certain that your signal source is not varying as much as your counts indicate?
Are you using the "classic" NE555 or a CMOS equivalent? Have you tried a more stabile signal source, e.g. a counted-down version of your crystal oscillator, just to see whether your problem lies in your code or in your signal source? Hopefully you aren't misleading yourself with a low-quality oscillator. If you divide your crystal oscillator by, say 15000 (easily done with four 74<insert technology designator here>161's or the like) you'll have a very stabile clock against which to check your counter code. Once you've gotten the code issues settled, you can go back to your 555-version. You may find, BTW, that a CMOS inverter with a resistor in feedback, and, perhaps, a small cap on its input, provides at least as good an oscillator as a 555. RE |
| Topic | Author | Date |
| Frequency (Event) Counter Problem | 01/01/70 00:00 | |
| less than 1% error | 01/01/70 00:00 | |
| Error % is incremental. | 01/01/70 00:00 | |
| ;STARTING BOTH THE TIMERS AT THE SAME TIME | 01/01/70 00:00 | |
| Less variations in TL0 but still error | 01/01/70 00:00 | |
| I do not know, but | 01/01/70 00:00 | |
| CRO Frequency Measurement | 01/01/70 00:00 | |
| Better But Still An Issue | 01/01/70 00:00 | |
| How stabile is your signal source? | 01/01/70 00:00 | |
| Very Good Point... | 01/01/70 00:00 | |
| Easier if 89c52 is used | 01/01/70 00:00 | |
| How stabile is your signal source? | 01/01/70 00:00 | |
NE555 is popular but not a precision device | 01/01/70 00:00 |