External display TM-V7

Many radioamateurs has find the way to this page. Originally it was written in the Dutch language, but there are many, many visitors worldwide with interest of the display. July 2021 I decide to delete my whole website. Life changes and it costs a lot of time to keep this website accurate. But, after I delete my webpage, I still received E-mails with questions about the display.

I discovered a non-working website at March 2022. Backup's don't work, so I have to start over again. That was a change to re-publish the Kenwood TM-V7 display page and so it happened. I only publish the English version of it, so it is useful for everybody. Sorry for the maybe incorrect English, I try it, but I'm not an expert.

First of all, thanks for visiting this page. It shares the same information that you can find on the website of Mario, OE9MKV. Maybe you find here some hints and tricks that you can use.

ATTENTION!
I'm NOT the owner of this project! This website is ONLY for supporting purpose!

SOMETHING TO THINK ABOUT
Please keep in mind, the last Kenwood TM-V7 was produced around 1999. That's 24 years ago... If you want to build this display, it's your descision, it will work anyway. But, after 24 years, there are maybe better alternatives to use or buy...

Unfortunally, I don't build displays, I don't sell displays, if you want a display, you have to build it by yourself...

It has to be Kenwood's best transceiver. Flyers, advertisements and lovely words... Blue display, double VFO, many options, special data-port, a big memory... great great great! But, it was Kenwood that produces a bad quality display. After a few years the first problems are coming... Lines in the display... horizontal, vertical... untill the most of the display was unreadable.

After discovering the problem, Kenwood changes the production and produce new displays. Users with old unreadable display, can send them back to Kenwood and receive another, good working display. But, this service stops very quick, so many people have now a great radio, with a unreadable display. Untill today...

I found the website of Mario Kienspergher, OE9MKV and wow... he made a external display for the TM-V7! If I build that display, I can use my transceiver again... Okay... So, I made an external display and yes, it works! With confirmation of Mario, I write this page. Again, sorry for the English language, I do my best to explain everything.

Disclaimer: the information, text, pictures and schematics are usable on your own risk! Mario and I are not responsable for any damage to you, your transceiver of other things or people. We are also not responable for any other damage or failure that is happenend using this information.

The problem of many 'blue wonders'. An unreadable display...

New displays are not avialable anymore. After the service of Kenwood, there are some webshops with new displays. Costs? Around 150 dollar! Very expensive. And, that price was without any TAX, shipping or other costs.

After years of silence, Mario Kienspergher (OE9MKV) has made a external display that you can use for the TM-V7. Okay, originally it is not the answer for the problem, but now you can use your TM-V7 again for local communication or you can build it in in your car!

Okay, I have a Kenwood TM-V7, so I want to try to make a display for it...

Mario has written two documents. One in the German and one in the English language. He also published the HEX-files for the Atmega processor. But I had some questions when I build the display. So I asked Mario and he gave me the information I need and with that information, I have build my own display. After that, I want to share the information with other people.

ATTENTION!
Please download the building instructions! In this PDF-file you'll find the schematics and description.
This webpage has ONLY a supporting function!

You can download everything below:

oe9mkv display This setup is the external display of Mario, OE9MKV.

Mario has written the constructionmanual where you can find usefull information. I keep it short and I'll not describe to much technical details. The display communicates with a very simple protocol. You connect the external
display to the data-port of the V7.

Limitations of the external display, please read this before you start!

There are a few limitations for the external display. The limitations are from the V7 itself or they cannot implemented in the firmware.

1 - If you transmit on the 70cm-band, the communication between the V7 and the external display blocked. Transmit on the 2-meter band has no effect on the display. It seems like a problem in the V7. Reconstruct the cable or using ferritclamps, has no effect. Mario ask me also for the problem and yes, I have the same problem here. There is no solution for it.

2 - You can give a name to all the memorychannels. However, the names of the memorychannels are send on the dataport, but cannot be displayed due a technical limitation. There is no such space to display the names. You can maybe change the firmware to get this to work, there is enough RAM, ROM and CPU-power.

3 - Only the features that are send on the dataport, are supported. That means that the menu cannot be displayed. Changing the frequency-step, repeatershift and other options must be programmed on the TM-V7 itself. Maybe you can read the display enough to change these functions, maybe you have to look in the manual of the V7. It's not clearly if these options are avialable at the data-port.

4 - If you choose the scanning-function on the V7, the scanning-mode works, but the V7 didn't stop at any frequency if there is a signal. This is a limitation of the connected display. The TM-V7 turns into a special data-mode with connected display and that cause this limitation. The reason is unknown, but Mario thinks there is a bug in the V7's firmware.

Okay, you decide to build your own display. Great!
Below a list of components you need. Here we go!

Building the display:

- A 4x20 LCD-display, blue backlight and white characters.
- A small experimental PCB
- Three ceramic capacitors of 100nF
- One 7805 (1A) voltage regulator, a 78S05 can give 2 Ampere
- One resistor of 10 KOhm (1/4 Watt)
- One potentiometer of 10k for the contrast of the display
- A 28-pin IC-socket
- One Atmel ATmega8 (also named AVR, that's the term I use on this page)
- A 6-pen S-VHS connector for the connection with the data-port (see text)
- A piece of 9-pin flatcable for the connection between the PCB and the display (see text)

Building the programmer:

- Small piece of experimental PCB
- A 28-pins IC-socket
- One meter of 6-pin kabel
- Three resistors of 220 Ohm
- One resistor of 100 Ohm
- 25-pin male connector for the printerport (LPT-Programmer)

It's very funny to build this display. There is one note that I must give you. If you don't know anything about programming an AVR, it could be difficult to understand what you doing and how it works. You must change some very crucial settings and if you do it wrong, it can give you a lot of stress. If you make a mistake with programming, your AVR doesn't work. If that happens, you must have a professional programmer to get it back to work. On this page I'll let you see how to program the AVR in the right way.

Please keep in mind, do NOT change other parameters, they don't work!

The programmer

You can make a programmer very easy. Four resistors, an IC-socket, a 25-pins connector and some cable, that's it. I made this programmer in a split second and it works very good. I suggest to use Windows XP for programming. I tested the cable with Windows 7, but that doesn't work here.

You can solder the IC-socket and resistors on a small piece of experimental PCB.
With this construction it is easy to program the AVR.

Why the LPT-port? Well, it's very simple to build a programmer for it. If you use the COM-port, you have to make a bigger programmer with MAX232 IC. We will keep it simple and mostly you are program the AVR once and that's it. Why expensive? I'll keep it on the cheaper way.

This is the schematic of the programmer:

A very simple LPT-programmer for the ATMEGA8.

If it doesn't work, you can use a external 5 Volt powersupply.

Ground goes to pin 19 of the LPT-port, pin 8 of the AVR and the powersupply.

Put a positive 5 Volt on pin 7 of the AVR.

Attention! It is possible that the voltage on your LPT-port is too low. If it is, your cable don't work and you have to put 5 Volt on pin 7 of the programmer. If you do this, please disconnect pin 7 from the LPT-port! Otherwise you'll blow up your LPT-port. And even so, connect the ground (pin 19) to your external power supply.

PonyProg

PonyProg is a user-friendly program to program different AVR's. The program knows a lot of options, only the options that are nesessary we descibe below.

Attention!
PonyProg doesn't work with Windows 7! I discovered a problem with the LPT-port.

Please use a computer with Windows XP or lower!

Install PonyProg and we have to set the right programmer.

Choose SETUP and then INTERFACE SETUP.

After that, choose for 'AVR ISP I/O'. Parallel and LPT1 are also needed.

Choose on the "INTERFACE SETUP" for "AVR ISP I/O" and choose LPT1.
Do not change any other setting!

If you set this, please choose the right microcontroller. You can see the setting in the right-top of the image.

Choose here for 'AVR Micro' and the Atmega8.

If everything is configured right, your programmer must work now. Please put the AVR in the IC-socket in the right direction!
Then connect the programmer to the LPT-port of your computer. If you have done that, please try to read the AVR.

You can do this by clicking the left icon from the second row of icons. If you get an error-message, please check all the connections and remember the external 5 Volt option! Maybe your LPT-port doesn't give the right voltage to the programmer! If everything works, the AVR can be read.

Well, and now the difficult part of programming the AVR... It costs me several hours to understand what I was doing wrong. Theory: every AVR runs at his own internal clock with speeds of 1 MHz, 2 MHz, 4 MHz and 8 MHz. The standard factory speed is 1 MHz. But for this external display it MUST run on 8 MHz. If you don't change these setting, your display won't work! The speed is necessary for the communication with the V7.

For the technical guys: please don't try an external X-tal, only at 8 MHz the display will work!!!

Here we go! Choose at PonyProg for COMMAND and then SECURITY AND CONFIGURATION BITS.

Choose below the pop-up screen for READ. If everything is fine, you see this:

The original read-out of the AVR. Change nothing, it makes your AVR unusable!

We have to change two settings. LOOK VERY GOOD AT THIS POINT!!!

Uncheck the mark at CKSEL2 and check the mark at CKSEL0.

The RIGHT settings: only UNcheck CKSEL2 and CHECK CKSEL0. Click now on WRITE.

Click now on WRITE. This settings will be programmed in the AVR. If you make a mistake here, your AVR don't work.
If it don't work at all after changing this, you have to get a professional programmer with more options to reset the AVR to his original state.

And again, please do NOT add a external X-tal for more speed, the AVR MUST and can ONLY communicate on 8 MHz speed with the V7!

Okay, this was the difficult part of programming the AVR. Now we have to program the AVR with the right firmware. Please unrar the software that you've downloaded from here or from the website of Mario, we use the same software. If you unrar it, you see a file with the extension .HEX. That's the complete firmware for the AVR. Now we have to program it in the AVR.

Go to FILE and choose 'OPEN DEVICE FILE'. Select the .HEX file and open it.

Please don't be scared of you see a screen like this below, it's just the code for the AVR.

Here you see the complete firmware.

Well, you cannot much with the information, but we gonna program the AVR.

Look at the screens below.

If you load the .HEX-file, please choose here for: WRITE DEVICE

The HEX-file goes straight to the AVR...

At the end of programming, a verification follows and... write succesful...

If you see this; 'Write succesful', congratulations!

Everything is gonna be fine and you programmed the AVR with succes!

Connect the TM-V7

Okay, after a while I want to connect the display to my V7. So, I soldered a mini-din connector and... hmm... it doesn't work. I thought it was the programmed AVR. Maybe I forget something or... I don't know. After a while I discovered the problem. I heated the mini-DIN connector too much, so one of the pins didn't make contact with the connector in the TM-V7.

My mistake, I heat up the connector too much, so this pin didn't made contact...

Look out for this kind of fails. Another important thing: if you connected the display to the data-port and turned the V7 on, it must give a beep-tone. This tone is an indication that the V7 is getting into the data-mode. If it do not give the beep, please check all your connections! Even check also if you have connected pin 4 and 5 together!

Flatcable between the display and controller PCB

A very simple solution: use an old piece of an IDE-cable or floppy-drive cable.

It's very cheap and works fine for this project!

The LCD-displayand background lights

Connecting the display is easy. But if you want to turn the backlight on, you have to connect two pins of the display.
Pin 15 is the plus (anode) and pin 16 is ground (kathode). Please connect pin 15 to pin 2 (5 Volt) and connect pin 16 to pin 1 or 5 (both ground).

On some display's, the connections are on the left or right side of the display. Please take a look at the datasheet of your LCD-display for the exact position of the backgroundlight connections.

The Results...

After days, weeks and years of development, programming and construction...