In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Zoot wrote:

I had heard that the Key's clock was a little flakey, but I thought it would be enough for Serin cause its supposed to be async.

> I think they are having some production problems with the next-gen of Key's but I have never had problems with SX-Key generated clock source

I'll toy with the two resonators that came with my SX tech tool kit. Besides unplugging them before hooking the key up,
is there anything I should be aware of when using them? If I can even see them... the numbers on these things are so
small its almost impossible to read them.

> Nope. Although you can PROGRAM a chip with resonator installed; but you won't be able to use SX-Key as clock source nor debug with resonator installed. In the interest of dedbugging your program, you could just yank the resonator and use the Key -- this will let you experiment with different freq. settings without swapping resonators. Plus being able to debug.

Which would be better for serial communication at 2400... the 4Mhz or the 50Mhz? Is there any harm in having the clock
too fast?

> You should be able to use either. See the SX/B docs for maximum serial rates at different frequencies. The only "problem" -- or feature -- with using faster clocks is that a) your settings and any external components must be correct so the resonator starts up, and b) the faster the chip is clocked the more power-hungery it is. See the SX data sheet, but the amount of extra current consumption between 4MHZ and 50MHZ is not insignificant.

And my question about True on serial communication is because I've never heard of the terms True and Open... Inverted
and non-inverted I get but not True and Open.

> true = non-inverted (i.e. 1 = high = yes = true)
> open = serial line is "pulled" high and driven low. In other words, any device that uses the serial line "releases" it to let it get pulled high (usually by making the serial pin an input) and drives it low. This allows multiple devices to share the same serial line without risk of short-circuit (if one device drives the line high while another drives it low, smoke ensues).

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