| Electronics > Projects, Designs, and Technical Stuff |
| 3 Dollar Precision Frequency Standard |
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| Alex Eisenhut:
Did someone say three dollars? |
| netdudeuk:
Could this be easily made to run with an AT Tiny85 ? Or a 328P ? |
| paulie:
328 may not be favorable because it is not code compatible with m8 and provides no actual advantages. Tiny85 however is code compatible with m8. So much so that I have many hex files that run on either chip un-modified. In my case m8 was chosen because it was available at lower cost than any other AVR including the Tiny series. Even bottom of the line Tiny13. Mechatrommer hints that an MCU with PLL would allow multiples of the input clock to be generated. The Tiny85 does have a PLL capable of 64x but unfortunately only works with internal "calibrated" RC clock which is useless for a precision frequency source. Maybe STM or some other processor has ability to use external clock with PLL. That would be nice. BTW I was able to double and even quadruple oscillator frequencies using 74hct86 XOR gates with a couple resistors. Unfortunately that does increase complexity/build-time and bust the $3 barrier. Also maybe tough to fit in that cheapo case/battery holder. |
| netdudeuk:
Does the attached hex file run directly on the Tiny85 ? Thanks. |
| paulie:
It's been a while since I played with that code but IIRC this version does not run on ATTiny. I do have a version that definitely does run on both and could maybe dig it up if there's interest. It was a little different regarding divider selection. Instead of one hit you had to enter four groups of button pushes to define the divider. This has the advantage of skipping ahead to virtually any frequency without needing to push up to 65536 times. I went with the one push version here because it's simpler and only the first few frequencies as seen in that table are compatible with my new counter. It also sends the numbers out serial at 57kbaud. Maybe this version does that too, but I'm not positive. |
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