Hi All,

My current project uses an 18F45K22 to pick up some data from a serial GPS.
I merge some other data in with this NMEA data and sent it out on the other
serial port to the PC. I hold the GPS data in a ring buffer on the PIC. I'v=
e
decided to use a trimble TSIP-like protocol for my data, because I already
have a load of code written to handle this on the PC. So I have a few TSIP
packet types, one for an NMEA sentence, one for my other data.

The output data stream is async, 57600 baud. My pic is clocked with a 16MHz
crystal and PLL on. BRGH=3D1, BRG16=3D1 and my SPBRG value is 0x0115 which =
by my
calculation results in a baud rate of 57552 which is 0.08% out. I am using =
a
MAX3232 as a level converter.

Now, the problem: when i connect my circuit to a (generic, chinese
made,prolific chipset) USB->Serial converter, after a couple of minutes of
successful data streaming, the data seem to become corrupt. As in, the
actual data received on the port is garbage. How long before this happens i=
s
variable.

Every single time, If I stop and restart my PC program, the data is OK
again.

I've cut the PC program back to bare-bones, and just had it write the raw
received data to the disk- this data stream becomes corrupt. It's not my
program messing up the data, it really does become corrupt on the receive.

I then changed to a "real" serial port on my PC, and the data is fine. I've
run the program for 24 hours, continuously, and every single byte received
was perfect.

So, there is something funny with the USB serial convertor, or my interface
to it.

Has anyone had similar issues? or do you have some ideas for investigation?
I should rather like my circuit to be reliable with usb-serial converters a=
s
well as with real serial ports.

thanks

slip
--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.