c2po's blog archive for July, 2011 - RC Groups
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Archive for July, 2011
Posted by c2po | Jul 28, 2011 @ 12:37 AM | 13,855 Views
Interesting... I didn't think it would be that easy.

It is a well known fact that FrSky Tx modules (and receivers too) use RS232 as interface, therefore connecting them to a computer might be kinda problematic.
Basically there are three options:
- find a PC with a real RS232 COM port, usually old PC and laptops have it, and use a RS232 cable that came with the module;
- buy a RS232 to USB adapter - proves to be the most problematic since most of the adapters are not properly working under newer versions of Windows, like Windows 7 x64;
- since RS232 uses inverse voltage levels comparing the FTDI TTL levels - build a signal inverter using two transistors which is kinda messy, but then you can use any FTDI adapter, usually no drivers needed, works with every version of Windows, just plug it in.

Last option is the most preferrable because probably anyone who messes with microcontrollers should already have FDTI cable or adapter anyway.
I decided to look inside the FrSky Tx module to see if I can find an easier way than finding four resistors, two transistors, and then solder all that stuff on some board, and then putting it somewhere... Hmm, there's a Sipex SP3232E chip that provides the RS232 output levels and actually does quite opposite from what I need - it converts TTL levels into RS232 levels. So why don't I just circumvent those two inverters... then I would get normal TTL levels!

Tiny soldering iron - check, helping hands with magnifying glass - check,...Continue Reading