Zanchius wrote:
Good morning all,
This is proving to be another hard to find component, so I got a 2MHz one instead. If I understood correctly there's a direct correlation with the terminal baud rate provided by the UART. Would 200KHz make much diference?
Hi Flavio,
Yes, I'm having trouble getting the 1.8 MHz resonators as well. Mouser quit carrying them, so I bought my last batch from Tayda2009 on ebay. But they seem to have gone out of business. As for the FJN3303 and FJN4303 transistors, I have enough for customers; but shipping to the UK is expensive.
The frequency is critical to get the right baud rate. Changing from 1.8 to 2.0 MHz will change the baud rate from 9600 to 1066 baud. It will still work if you can set your Terminal program for such an oddball rate.
A better solution is to get a 1.8432 MHz crystal, which is a standard frequency and fairly easy to find. Crystals don't have the internal capacitors, so you'll also need to add two 20pf capacitors, one from each side of the crystal to GND (the schematic in the manual shows these capacitors).
Another option is to change the divisor in the 8250 UART. This can compensate for your 2 MHz resonator. But it means changing a byte in the EPROM, and burning another one.
Lee
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A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
-- Antoine de Saint Exupery
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Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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Lee Hart