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Software UART Problem PIC 18F2550

Posted: Mon Aug 08, 2011 9:03 pm
by PICFriend
Hey there,

Im using the hardware uart RS 232 (115200,9N1) for RS 485 connection => ok

Also i want to use software uart RS 232(115200,8N1) for the comunication between PIC and Edip - Displays.

Everything is working fine but the display shows nothing.
I look the data on the line and there is nothing right.
It seems to be a timing problem with software uart or code.

Configuration:
WDT off
20Mhz Xtal PLL
Target freqency 48Mhz
Software uart 115200,8,N,1
Bootloader USB
No supplymentary code or things like that.

Any suggentions?

In another topic there is a "frig - facote" or a "trick - calculation" by i can´t find out any solution for my application.
Is there any calculation or code i have to write or change baudrates?
Are the software uart and the hardware uarts independent of each other?

Please help me :(

Thanks guys!

Re: Software UART Problem PIC 18F2550

Posted: Tue Aug 09, 2011 10:10 am
by Benj
Hello,

Which version of Flowcode are you running?

v4.5 was improved to allow for better software baud rates though 115200 is fairly fast for software.

Do you have access to a scope or similar which will allow you to view the signal timings going out of your device?

If not then let me know and I will have a quick look here.

Re: Software UART Problem PIC 18F2550

Posted: Tue Aug 09, 2011 11:18 am
by PICFriend
Hello,

Flowcodeversion is 4.3.7.63 Professional.

The zipfile contains the .fcf and two pictures from scope and recieved data on a terminal.

The PIC sends 85 decimal via software uart. The scope looks crazy and the recieved data is wrong also.

Final application should be hardware uart with 115200 Bd and software uart with the fast frequency that is possible. It is possible to set the display baudrate on 19200, 38400, 57600 and 115200 Bd.

Re: Software UART Problem PIC 18F2550

Posted: Tue Aug 09, 2011 3:42 pm
by DavidA
Hello,

Please post in the Flowcode V4 forums as you state you use Flowcode V4.

Help on how to do this is available here:

http://www.matrixmultimedia.com/support ... f=29&t=602

Re: Software UART Problem PIC 18F2550

Posted: Tue Aug 09, 2011 5:11 pm
by Benj
Also no zip file attached :(

Re: Software UART Problem PIC 18F2550

Posted: Wed Aug 10, 2011 9:26 am
by PICFriend
Hello together,

I fixed the problem with the scope. When i give in 34000 Bd in the RS232 (Software uart) properties then the scope shows exatly 26us and everything is working fine! Why, i don´t konw perhaps you got an answer.

Zip files not attached? => strange. Why not?
What means this from David A. "Please post in the Flowcode V4 forums as you state you use Flowcode V4."
This i have done (long time ago certainly). I try this again.

Thank you 8)