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? on external oscillators

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low_byte

New Member
Hi, I'm trying to build a external crystal oscillator to inject the clock-in pin on pic 16f84a chip. I have been using 4 mhz crystal clock circuit as described in microchip literature with no problem. However pic 16f84a smart card, (aka goldcard), only has clock-in contact and needs external oscillator to obtain correct baud rate. I tried r/c with the card and was able to blink a led ok, but I am unable to send text out to lcd display. I am pretty sure my code is ok because I can send text out over a dip package 16f84a chip with 4 mhz clock. I'm setting the fuse bits to xt, on the card so I'm pretty sure my whole problem is timing related. In r/c mode the card sends gibberish to the display. The oscillator circuits that microchip shows are parallel and series. Has anyone used one of these external circuits and would you please recommend which one to choose, or point me to somewhere that I can go and get informed. TIA, low_byte
 

Nigel Goodwin

Super Moderator
Most Helpful Member
I've never used one - but as I understand it, the clock oscillator is provided on one of the contacts from the host system. You simply set the PIC to use an external oscillator, which it picks up from the host.
 

brodin

New Member
Yes i suppose that this is how it works to, but sisnce there is only one pin, i can't use a crystal, right?
 

amr_karimm

New Member
hi,
i read that u looking for make oscillator of the gold card iam also making aproject of smartcard {whith fun card} and i have the same problem and i wish we can help each other if one have asolution u can mail me on
amr_karimm@hotmail.com
 
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