Weird WriteLn output

Well, yes, but it is not necessarily AVRCo even so. There are many layers of VCP and it could be the Microsoft part of serial driver, although I agree, if the output is entirely repeatable, this is unlikely. However, I did not find that it was all that repeatable - the error occurred pretty much in the same place but the output was not always exactly the same, although it did seem to mix the two lines of output. And sometimes two successive WriteLn statements did not produce an error, although it was always the same pairs of WriteLn statements that produced an error, not random. I think that your output shows the same symptoms from that point of view. I don't have time to do it at the moment, but when I get a chance I will hook up two machines (one XP and one Windows 7) to the same serial port and see if the same strings go to both machines. that should at least prove if it is the windows machines or AVRCo.

Thanks everyone very much! Problem solved now. I will share my/our findings for future reference here.

At first I tried compiling with old AvrCo 4.99, but after flashing to EvaBoard-485 the serial output was still weird in Win7 and Bray Terminal. It looked like it was AvrCo but I remember few projects back then who used serial a lot and didn't have this problem. Hmmmm.... Then I have connected to WinXP and the same output now showed well in Bray Terminal. Then I have connected the same output to Win7 but through Digitus SERIAL<>USB connector I had laying around. Output was good. Well, it must be Win7 serial driver, I thought. Wrong again! Searching the net for missing characters in Win7 serial driver showed nothing useful, so I switched to another terminal software, and output was finally good in all tested cases.

It turned out that my old trusty Bray Terminal, which served me reliably for more then 10 years, in version 20140110 which I was using, had a problem on Win7 with both internal motherboard serial port and FT230X on my boards, but not with Digitus SERIAL<>USB convertor. When I have reverted to old 20130116 version, problems were gone. Downloading latest 20140703 version also fixed the problem. I will test further but after quick tests everything looks good now.

Once again thank you all !!!

Hi Avra.

I use my own - a Delphi application using VCP (virtual comm port) application through FTDI drivers.