| ??? 01/07/09 13:57 Read: times |
#161361 - I do not know, but Responding to: ???'s previous message |
the contents of TL0 are still varying from 21 to 28,whereas the count in TH0 remains constant i.e 03. The frequency of 555 observed on CRO is 781Hz and according to LCD count it is 3*256+21=789Hz. And considering the maximum count 28, the frequency is 3*256+28=796Hz.
Are the variations because of frequency source IC 555 used as astable multivibrator 1) I do not know, but would guess that the 555 would vary that much, but since you are watching the output on a 'CRO' (which I believe means oscilloscope) you should be able to see jitter if there is any. 2) if your scope does not have a frequency display, your frequency reading will not be precice. If it does, it may be averaging and thus falsely giving you the impression that the frequency is stable. Erik |
| 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 |