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Author Topic: Resonator on the Leonardo?  (Read 1082 times)
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I'm designing a tiny custom board that will use the same microprocessor and bootloader as the real Leonardo. On a UNO type board I made a while ago I used Digikey resonator part: h**p://www.digikey.ca/product-detail/en/CSTCE16M0V53-R0/490-1198-1-ND/584635 that works great. I've seen the Leonardo schematic that uses a crystal with two external capacitors. Any idea if a resonator with built in 15pf caps will work on the bootloader thats is in the Arduino software? I'm hoping to load it into the Atmel chip using the USBtinyISP programmer.
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You might be able to get something onto the Atmega32u2 with a USBtiny (the USBtiny has a Crystal), but I doubt you will be able to use the Atmega32u2 with USB with the resonator as a clock source for the USB2TTL.
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Hofstadter's Law: It always takes longer than you expect, even when you take into account Hofstadter's Law.
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The key parameter is the frequency tolerance, which must be within +/- 500ppm of the USB specification. See http://www.cypress.com/?docID=26060 and http://www.ti.com/lit/an/slla122/slla122.pdf.
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It will work with or without the added capacitors. The added capacitors will slow down the oscillator a little.

In general, you should try to use a crystal, for its better accuracy / stability. The price difference is minor and there are many smd crystals.
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Just a quick update that the resonator on my Atmega32u4 is allowing me to upload sketches over USB. I wasn't expecting it to but it does. My 2nd rev has a crystal like all the others I've seen. I guess I just lucked out on this one.

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« Last Edit: October 26, 2012, 12:26:36 pm by 0miker0 » Logged

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