Menu:
OTRSP Antenna Selector
on ATMEL ATmega8 microcontroller
Many new computers don't have LPT port, usually used to control the antenna switch. To bring control via USB (Antenna Selector has internal USB to RS232 converter on FT232R chip),
my Antenna Selector uses Open Two Radio Switching Protocol (OTRSP) to communicate with computer.
It is possible to use LPT port to control Antenna Selector, too (BCD option).
Antenna Selector can switch up to 8 antennas. An option is using two Relay Boxes with 4 relays each. In this option
the last relay (Relay8) is always ON for antennas 4-7. Look for 8 Relays Box
and 2x4 Relays Boxes documents, how
to connect relays to Antenna Selector.
Hardware part of project was made using free KiCad software, program for ATMega8 chip was written using Bascom AVR software.
All source files are included.
Antenna selector uses:
Schema of the Main Board of Antenna Selector is as follow:
Schema of Display Board:
Below there are some photos of prototype of Antenna Selector:
Main Board PCB (PCB made using thermo transfer method) and Main Board assembled :
Display Board PCB and Display Board assembled :
And the final photos:
Antenna selector uses FTDI chip as converter USB/R232. So, for the first, driver for FTDI chips must be installed. It can be found on FTDI page.
If driver is installed, please plug-in Antenna Selector to the USB port and check in Device Manager,
which COM port number is assigned to Antenna Selector. This COM port number must be selected in logging software.
If port number has big value (Logger32 and WriteLog can use port number up to 16, Win-Test up to 12), it must be changed in Device Manager to lower.
I tested Antenna Selector with Logger32 and Win-Test, but I cannot to configure WriteLog to work with OTRSP (anybody do this?).
Files to download:
Antenna Selector main files Zip file consists schemas, PCB files, hex and eep files for ATMega8 
File version: 1.00, Date: 2013-12-12, File size: 156 kb KiCad projects Full KiCad projects for Antenna Selector. All libraries/modules includes, with PCB in PostScript format and 3D visualizations of the boards.
File version: 1.00, Date: 2013-12-12, File size: 658 kb BascomAVR project Source BascomAVR files with compiled hex file. Fuse bits must be set to $E3 $D9 (4MHz internal clock) during ATMega8 programming.
File version: 1.00, Date: 2013-12-12, File size: 26 kb