| ??? 05/26/07 14:30 Read: times |
#139871 - Isn't it slightly more complicated? Responding to: ???'s previous message |
Russell said:
900 pulses per min = 15 pulses per second. Most processors will have no problem polling 12 inputs of this speed. If you consider a lowly 12 clocker 8051 will execute 1million instructions per second - you can see 15 counts per second * 12 leaves us 5555 instruction times. All true, but there's one more thing to worry about, and that's the width of each pulse. Just for discussion, suppose the polling loop takes 120 microseconds to get around to looking at all 12 inputs. Now even though the pulses don't come any faster than 15 Hz, if any given pulse is narrower than that 120 microsecond loop time, the polling loop might miss it. So don't we need to consider the pulse widths as well as their frequency? -- Russ |
| Topic | Author | Date |
| 12 parallel pulses counting | 01/01/70 00:00 | |
| How fast are these pulses? | 01/01/70 00:00 | |
| pulses speed | 01/01/70 00:00 | |
| More info | 01/01/70 00:00 | |
| Pulse rate | 01/01/70 00:00 | |
| Isn't it slightly more complicated? | 01/01/70 00:00 | |
| Stretching pulses | 01/01/70 00:00 | |
| Another Quick Way | 01/01/70 00:00 | |
| Sampling timer with a buffer | 01/01/70 00:00 | |
| Showing Vertical Couners | 01/01/70 00:00 | |
| Yes other interrupt are also there | 01/01/70 00:00 | |
| Avoid using interrupts where possible | 01/01/70 00:00 | |
| Run signals frequency... | 01/01/70 00:00 | |
| PLC can be dirt cheap | 01/01/70 00:00 | |
| PLCs | 01/01/70 00:00 | |
an xcellent idea | 01/01/70 00:00 | |
| Sample with 2 74LS165 parallel loadShiftRegisiters | 01/01/70 00:00 | |
| would not the output pins drop... | 01/01/70 00:00 | |
| No Extra Hardware Needed | 01/01/70 00:00 | |
| No Extra Hardware Needed - I do not agree | 01/01/70 00:00 |