‰  NOW 40 WPM  ‰  
RADIO.  IN THE EVENT THAT BOTH RADIOS ARE TURNED ON, THEN BOTH ANALOG
INPUTS WILL HAVE POSITIVE VOLTAGE, AND THE SWITCH WILL PUT ALL PERIPHERALS
ON THE DEFAULT RADIO.  ONE EXCEPTION INVOLVES HOW THE UNIT IS CONFIGURED TO
HANDLE THE MICROPHONE INPUTS.  THESE INPUTS ARE MANAGED THROUGH RELAY BOARD
2.  BECAUSE I HAVE TWO MICROPHONES A DESK MIC AND A HAND MIC, I HAVE THEM
SET UP IN A CRISSCROSS CONFIGURATION.  IN THE DEFAULT INSTANCE, WHERE RIG A
IS SELECTED, THE DESK MICROPHONE IS CONN

A RECONFIGURABLE STATION COMPONENT SWITCHING UNIT  MARK C. NOE, KE1IU
AMATEUR RADIO STATIONS GENERALLY START OUT SIMPLE PERHAPS ONE ANTENNA, A
TRANSCEIVER, A STRAIGHT KEY, AND A MICROPHONE.  THEN YOU BRING HOME AN
ELECTRONIC KEYER AND PADDLE FROM A SWAP MEET.  ITS NOT A PROBLEM TO UNPLUG
THE STRAIGHT KEY AND PLUG IN THE NEW SET.  EVEN THE ADDITION OF A NEW
ANTENNA IS EASILY HANDLED WITH A DOUBLE THROW KNIFE SWITCH, BUT AS THE
STATION GROWS WITH THE ACCUMULATION OF LINEAR AMPLIFIERS, QRP LOW POWER
KITS, A SPECIAL RIG FOR SATELLITE WORK, NEW ANTENNAS, ETC., CHANGING THE
STATION CONFIGURATION BECOMES A RE CABLING NIGHTMARE THAT IS NOT ONLY TIME
CONSUMING, BUT PRONE TO ERROR.  MY WAY OUT OF THE STATION RECONFIGURATION
CONUNDRUM WAS TO DESIGN A RELAY SWITCHING MATRIX CONTROLLED BY AN ARDUINO
MICROCONTROLLER AND THE OPENHAB APPLICATION THAT WOULD BE EASY TO CONFIGURE
AND ALLOW FOR CONTINUED STATION EXPANSION.  SYSTEM DESIGN  I USE OPENHAB
VERSION 2R0, WHICH IS AN OPEN SOURCE SERVER APPLICATION THAT IS CAPABLE OF
INTEGRATING HUNDREDS OF INTERNET OF THINGS IOT DEVICES INTO A CUSTOMIZABLE
GRAPHIC USER INTERFACE GUI FOR MONITORING AND CONTROL.  OPENHAB INTERFACES
TO THESE DEVICES THROUGH DRIVERS CALLED BINDINGS.  THERE ARE UNIQUE
BINDINGS THAT CAN BE DOWNLOADED INTO THE SYSTEM FOR EACH IOT DEVICE THAT
ONE WISHES TO ENABLE.  OPENHAB IS CAPABLE OF RUNNING ON A WINDOWS, MAC, OR

UNIX BASED SYSTEM, SUCH AS A RASPBERRY PI MICROCOMPUTER.  MY HOME
AUTOMATION SYSTEM RUNS ON A RASPBERRY PI, BUT I THOUGHT IT WOULD BE MORE
CONVENIENT TO RUN A SECOND INSTANCE OF OPENHAB ON MY RADIO STATIONS PC,
AFFORDING DIRECT CONTROL OF THE ARDUINO THROUGH ITS USB PORT.  THE
FEASIBILITY OF THIS IDEA WAS REINFORCED BY THE EXISTENCE OF A SERIAL
BINDING FOR OPEN HAB, WHICH ALLOWS COMMUNICATION TO ANY DEVICE CONNECTED
VIA AN RS232 PORT OR EMULATOR.  THE ACT OF CUSTOMIZING THE INTERFACE COULD
THEN BE DONE SIMPLY THROUGH SOFTWARE BY MODIFYING THE ITEM, RULE, AND
SITEMAP FILES THAT CONFIGURE THE OPENHAB GUI.  HARDWARE THE HARDWARE FOR
THE ACTUAL SWITCH IS QUITE SIMPLE.  I USED AN ARDUINO MEGA 2560
MICROCOMPUTER FOR THE INTERFACE SEE FIGURE 1A.  IT HAS THE REQUIRED NUMBER
OF DIGITAL I/O INTERFACES AND IS AVAILABLE FOR LESS THAN 20 AT SEVERAL
VENDORS.  FOR THE RELAY BOARDS, I USED TWO SAINSMART 16 CHANNEL RELAY
MODULES.  THESE UNITS ARE COMPRISED OF 16 SINGLE POLE DOUBLE THROW SPDT
RELAYS, PLUS ALL OF THE SWITCHING CIRCUITRY TO CONVERT A 5 V DIGITAL HIGH
OR LOW SIGNAL TO THE APPROPRIATE SWITCHING STATE OF THE RELAYS.  FOR ANY
‰  END OF 40 WPM TEXT  ‰  QST DE W1AW  ƒ