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Message-ID: <5.1.0.14.0.20020126100638.00b020c0@POP2.sympatico.ca>
Date: Sat, 26 Jan 2002 10:09:52 -0500
To: "Johan Bodin" <sm6lkm.jbeab@swipnet.se>, 
 "Mitch Powell" <m_powell@sympatico.ca>,
  rsgb_lf_group@blacksheep.org
From: "Larry Kayser" <kayser@sympatico.ca>
Subject: LF: USART in the 16F628
In-reply-to: <00d401c1a5a3$a3137c20$9c2465d5@oemcomputer>
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Greetings:

I have for some days been struggling with achieving consistent and accurate 
serial port operation, especially when the Interrupts are being hit at a 
high rate.  The APNOTE from MICROCHIP does not work most of the time and 
never worked properly.  However a fine piece of work by Tom McGahee, 
PICUART.ASM for the 16C74A should be adaptable to the 16F628.

It was adaptable and works like a charm.  I have now tried this with the 
following Oscillator configurations.  For the 16F628, the Internal 4 MHz, 
an external 4 MHz crystal, a 1.8432 MHz crystal and with a high speed 
16F628 it ran just fine with a 21.7 MHz crystal.

I will send any and all who ask a copy of this ASM file, which I happen to 
call PIC8_4B.ASM, configured to run on a 4 MHz crystal or 4 MHz internal 
oscillator by just compiling it with MPASM.

I will decline to express my thoughts about Microchip documentation and 
product support.  It is suffice to say that my first copy of CPM-80, the 
one with both handwritten and typewritten documentation from Gary Kendall 
about 1976/7 was of higher quality and vastly more accurate than what I 
have received from Microchip for the 16F628.

Larry Kayser
VA3LK