Talking to a DEK

[Tishers]

I have a bunch of the HLN124D DEK heads and would like to put a few to use with a Micom 2 (five of those as well). Normally there is not DEK support for the Micom 2 but there is a serial HDLC data connection off of the back of the Micom 2 radio.

What I want to do is to use a small controller, like a Raspeberry PI to act as a serial translator/ communications bridge between the Micom 2 commands and the DEK head. Then I can map some of the radio functions to buttons and indicators to LED's on the DEK head. It is to try to make the Micom 2 a bit friendlier for ham use.

Does anyone have any familiarity with the communications protocol for the DEK heads? It should be fairly simple, it looks just like digital logic to map I/O from the buttons and lights. I know it is synchronous serial (clocked) and I can deal with that.

I doubt anyone knows the HDLC serial message structure out of the Micom 2 but I can put a protocol analyzer on the comms port and map the functions. I have some experience in doing this with Harris gear and their serial communications messaging.

Please, if you have any tips I would really appreciate it. Contact me on (or off) list.

Ms. Tisha Hayes
AA4HA

[Mike B]

You are missing a numerical digit in your part number. The complete part number might be HLN1241D. If this is correct then the following information applies.

Take a look at the DEK Functional Block Diagram on this page:
http://www.onfreq.com/syntorx/syntorx9k/dekx9.html

The clock shifts the data inside the registers one bit at a time. The strobe transfers the shift register parallel data to the output pins on the output chips and it loads the parallel input shift registers with whatever logic level is present on its input pins. The strobe pin allows you to load/read the shift registers without having the input/output pins changeing with each individual clock shift. It's sixteen clocks and one strobe. You just need to determine the correct logic levels and edge timing (which transition edge shifts the data) for the clock and strobe. You can look at data sheets for shift registers like the 74164, 74165, 74595 to get some ideas of what might work. Sorry, if I ever knew which chips are used in the DEK I have forgotten it a long time ago.

Mike Blenderman
K7IC

[Tishers]

Mike,
Thanks so much, I am pretty comfortable with digital logic and being able to toggle a line to strobe the data in and out of the shift registers. I did that type of design work back in the early 1980's. Now that I look at the very simplistic way that the hardware is structured I feel confident that I can handle the hardware part.

For reading the radio I am going to hook up a protocol analyzer to the 44 pin connector on the back of the chassis and capture the HLC messages.