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Steven,
I have designed, built, manufactured well over a million PIC MCUs with RS23=
2
since late 80's when it was not Microchip but GI.
Started out with crystal, then ceramic resonator and now 4/8mhz internal os=
cillator.
Bit-banger then internal UART.
I have used 9600 baud N81 with confidence.
Yes, it does help to know what is on the other end.
Accuracy tolerance starts with the start bit.
That starts the sample on the other end.
I have found that most RS232 receivers will tolerate +/- 50% error over 10 =
bits (5% per bit)
That is why I was able to use 5% ceramic resonator.
Temperature range was 40F to 100F

The first internal UART was PIC16F913
There is a nice error table there
http://ww1.microchip.com/downloads/en/DeviceDoc/41250F.pdf
TABLE 9-5: BAUD RATES FOR ASYNCHRONOUS MODES
page 135 in pdf reader (marked page 133)

Ray
Profile: http://www.linkedin.com/in/ranewman


On Wed, 18 May 2011 21:24:27 -0500, Steven Ramon wrote:
>
>?I am planning to use a PC18F2455 for RS232. To help save cost and
>?reduce complexity, I want to use the internal oscillator. However,
>?I'm concerned about baud rate error. We'll be operating at 9600 8N1
>?and 5V signal levels. Can someone point me to documentation that
>?discusses using the internal oscillator with RS232. I've searched
>?for an application note, but haven't found one. Please go easy on
>?me, as I have never used this forum before and don't even know if
>?it is going to get through.
>
>?Thanks,
>
>?Steven




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