Hi Matt

A couple of pieces of info are missing here.
What is the clock source of your pic (X-tal, internal rc etc)
and how do you convert from RS232 voltage and polarity to logic
How accurate is your baudrate calculated from clock and or actual
if you can measure it.


Commercial USB to rs232 converters (even cheap ones) are usually
pretty good in level and timing. Is there any other device to test your setup with?

Peter van Hoof



----- Original Message ----
> From: Matt Rhys-Roberts <matt@nu-ins.com>
> To: Microcontroller discussion list - Public. <piclist@mit.edu>
> Sent: Monday, July 27, 2009 6:04:36 AM
> Subject: [PIC] 18F8627 USART receiving random MSBs?
> 
> I have a curious problem when I'm transmitting ASCII character '5' via 
> RS232 to USART1.
> 
> It seems to be *alternately* receiving 0xB5 instead of 0x35, i.e. the 
> MSB is erroneously set, about 50% of the time, and only seems to be 
> failing on this character! (NB: WUE (wake-up enable bit) is disabled, 
> which I know gives receive errors when enabled).
> 
> I've set USART1 up for asynchronous reception, 9600 baud, 8N1. I 
> transmit from Hyperterminal into a USB-RS232 converter ("Prolific 
> USB-to-Serial Comm Port").
> 
> I suspect flakiness in the converter, in absence of any other means of 
> verifying its output, so will try masking the Rx'd MSB as a hack for 
> now. But if anyone's got any bright ideas, please let me know.
> 
> Kind regards
> Matt
> -- 
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