DTMF_Shield

The Arduino DTMF Shield and software to program a Kenwood TM-742 series radio

This code and designs all came from Larry Anderton, WA7YLI. It is released with his expressed permission.

Many thanks to Curt Mills, WE7U, 'the Xastir Guy', who loaned me his functional TM742 Programmer unit, so that I could test my built boards initially, and to know correct from incorrect, or unexpected, behavior.

License is listed as MIT, but other open source licenses are also acceptable, especially BSD, Mozilla, or GNU 2.0.

Hardware designs are licensed under the TAPR Open Hardware License

This consists of:

1. an Arduino Sketch called DTMF_Shield, which runs on an Arduino Uno. I've recently tested an Uno R3, and it worked.
2. an Arduino shield, called 'DTMF_Shield', that generates DTMF tones and otherwise emulates a Kenwood MC-45DM microphone or equivalent
3. a Visual Studio VB.Net application that, using a DTMF Shield on an Arduino, will program a Kenwood TM-742 series radio the two zip files are the original installer and the original Visual Studio source code. It was called 'UsbTest' then.

"TM742 Programmer - Rev 1 candidate Jul1 1, 2014.zip" is the original installer as provided by WA7YLI. This is also what the 'initial release' gives you.

"TM742ApplicationSln.zip" is the original source code from WA7YLI.

If you are using Arduino IDE 1.x, place the Messenger folder inside your Documents\Arduino\libraries folder. Open the DTMF_Shield sketch. Use 'upload' to put it onto an Arduino Uno that is plugged in to the computer and recognized.

I've tested this also with Arduino IDE 2.0. it works, but there wasn't a Documents\Arduino\libraries folder already existing; I had to make it. But the compile, and the Upload, also worked as well as with the Arduino IDE 1.x.

I suspect that this project could be modified to easily program the Kenwood TM-732, and possibly TM-733. It can also be a generic DTMF generating board. The Arduino is just a serial port that accepts commands that are processed by the DTMF_Shield sketch. DTMF tones and button presses and such result from this.

Note that it is possible that this code will work on a Mac or on Linux using Visual Studio, in some form. You would have to edit the code related to how Arduino unit interfacing and identification work. The current code attempts to open SerialPort objects for devices with names like 'COM1' and so on. For example, on a Mac, I see a serial port Arduino on port '/dev/cu.usbmodem14101'. On Ubuntu 22.04LTS I saw a device name like '/dev/ttyACM01'.

VS IDE and VS Code seem to want to do only C# on a Mac. VS Code only wants to do C# on Linux. So converting the code from VB.Net to C# is in order. Using ICSharpCode.CodeConverter vsix plugin for vs2019 (or vs2022), I've converted the VB.Net original project/solution to CSharp. 4 minor code changes were required. The result looks like it runs. It does in fact run.

Mac and Linux do NOT want to do Windows Forms applications (which is what the programmer app is...) any more. I think that maybe 10 years ago we could create the app on windows, and run it under Mono. However, the Mac and Linux seem to use only .Net Core, which does not include support for Windows Forms apps. It no longer works that way. It looks like the way forward is to convert to a Xamarin app. But I could be very wrong, and chasing alleged unicorns.

I have and use MacOS and Linux myself, but help is appreciated!

What the DTMF_Shield sketch does:

1. it processes a set of serial command strings. Some are single character, some are multiple character. These commands/actions are described below.

2. to operate the shield itself, either a command setting a value is sent, a button press is emulated, or a 5 bit command is sent to the DTMF generator chip (HT9200A) to generate a tone for 0-9 or A-D. The chip is enabled, the 5 bits are banged out, and the chip is disabled. There are appropriate pauses.

   a) setting values: accepts "SET_TONE_TIME:" followed by an integer value, or "SET_BUTTON_TIME:" followed by an integer value, "PAUSE: ", which causes a pause for TONE_DELAY time (SET_TONE_TIME value) Default values for both are '75'. All values are in milliseconds

   b) receiving the string "0" thru "9" and "A" thru "D" cause that DTMF tone to be generated by the HT9200A chip, for the current TONE_DELAY time.

   c) receiving the string "UP" causes the UP button press line to be set for BUTTON_DELAY time (SET_BUTTON_TIME value), then cleared. Similar for "DOWN", "MR", "VFO", and "CALL"

Long and short presses are performed by having the TM742 programmer application change the TONE_TIME and BUTTON_TIME appropriately, then returning to the normal value. A possible improvement could to build in things like 'short MR' and 'long MR' by having more time values that can be set. But those actions can already be performed with the commands that are now present.