TeraTerm and Xmodem.. going crazy!

[ikalogic]

Hi there!

I have spent the last 2 hours banging my head around a problem. I am starting to feel very stupid about it!

Okay, i created a simple text file with the content "hello world".

I want to use Teraterm and xmodem protocol to send that file to a micro controller. till ther seems pretty simple right?

Okay, i read all about Xmodem, and implemented the protocol, which seems to work like a charm (sends the ACK when it needs to), and teraterm does not complain about anything.

In my program, i store the payload in a 128 bytes buffer, and then, when the transfer is finished, i display it back on the terminal window.

Problem is: I never get the original "hello world" that was supposed to be sent.

I don't have a L.A. right there so i can't sniff the serial port, i am not at the office. (yes, even a logic analyzer manufacturer can find himself without a L.A. someday!! )

Anyway, I tried to find *any* relation between the original file and the final outputted string, but i can't find any.

Simple question: Am i getting something totally wrong here? shouldn't XMODEM be plain binary data transfer..? is data transformed in anyway..?

Thanks a lot!

ps: I usualy never use xmodem, but thought: let's not reinvent the wheel.. Seems like reinventing the wheen would have taken less time.. but hell, i want to know what is going on with that serial link!

 

[Nigel Goodwin]

Fairly obviously, you're doing something wrong

XModem works perfectly, and does exactly what it's supposed to do - but you also obviously don't need it to send simple ASCII like "Hello World", it's for sending 8 bit non-ASCII data.

I've never had reason to do it on a PIC, but I did it in Turbo Pascal a LONG time ago, for a Packet Radio Program I wrote.

 

[ikalogic]

Hi Nigel,

Thanks for your reply. a "hello world" txt file is still formated as 8 bit data... (i verified with a hex editor, although it's obvious, but who knows).

I'll post my source code later.. although pretty simple as this stage.. I just store the received data in an array, and write it back on the teraterm terminal window at the end of transfer...