slippyr4 wrote:
> Hi All,
>
> My current project uses an 18F45K22 to pick up some data from a serial GP=
S.
> I merge some other data in with this NMEA data and sent it out on the oth=
er
> serial port to the PC. I hold the GPS data in a ring buffer on the PIC. I=
've
> decided to use a trimble TSIP-like protocol for my data, because I alread=
y
> have a load of code written to handle this on the PC. So I have a few TSI=
P
> 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 16M=
Hz
> crystal and PLL on. BRGH=3D1, BRG16=3D1 and my SPBRG value is 0x0115 whic=
h by my
> calculation results in a baud rate of 57552 which is 0.08% out. I am usin=
g 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 o=
f
> 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=
 is
> 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 receive=
d
> was perfect.
>
> So, there is something funny with the USB serial convertor, or my interfa=
ce
> to it.
>
> Has anyone had similar issues? or do you have some ideas for investigatio=
n?
> I should rather like my circuit to be reliable with usb-serial converters=
 as
> well as with real serial ports.
>
> thanks
>
> slip
>  =20

I would try:

SPBRG value of 0x0114 and 0x0116

9600 baud

A delay between each character sent

Just to see if any make a difference.

Kerry





--=20
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