| ??? 02/29/12 19:31 Read: times |
#186294 - A number of thins concern me ... Responding to: ???'s previous message |
Mahmood Elnasser said:
I have a small project to make 10x frequency multiplier, frequency input 1Hz to 70Hz frequency output 10Hz to 700Hz.
I could do it with old techniques like frequency to voltage converter or PLL but that will be boring, hi IC count and pcb space. I want to do it with single chip micro in C or ASM or both. Frequency input is ac but I can convert it to pulses, frequency output is a TTL square wave. My first thought is to measure the input pulse width and generate simple dds algorithim. Any better ideas? Mahmood What, exactly, is it that you find boring about using a simple, though long-established method for solving this relatively trivial problem? A PLL with wide capture range can easily deal with this problem, and, as others have already stated, it only takes a coupld of IC's and a few cheap passives requiring perhaps 3 square centimeters of PCB space. It can even be done with one CMOS IC, e.g. one of the MC14515x or 14517x series frequency synthesizers. I previously mentioned rate multipliers, e.g. 7497 or 74167, or CD4089. If they are too costly (the CD4089 costs $0.52US, IIRC) you can probably replicate all their functions in firmware, since you're operating at a snail's pace frequency. You haven't really stated what your ultimate goal is. Do you wish to control/adjust the operating speed of the motor, or just display its rate? RE |
