Monday, January 25, 2010

TinyTrak4D Project

I wanted to post my results of my TinyTrak4D project to the Amateur Radio Community, in hopes that someone might get an idea from me, or this would help somebody on their project.


This is my TinyTrak4D Project box, I will have to work backwards on the construction. Because moding the case is pretty messy, and makes a lot on imperfections that look bad, I wanted to cover it all up while labeling stuff. I used a 8 1/2 x 11 white label paper from Staples, as Walmart didn't have any sticker material that would have worked. Felt cloth and glue wasn't an option. After labeling everything, I covered the label with a wide scotch tape to protect it.

I got the light from the TinyTrak4 board to show through the case. I added a battery pack onboard for internal power, the ability to turn off the LCD backlight, Backlight Adjustment, GPS Power, and switchable config option.

For the left side, I made all the connection points to simplify the interface and not make it as cluttered when using it. I made PortA available for interfacing (Currently used for GPS), the Radio port, a RX Line In so I can use my box for monitoring APRS only, A switch so I can change the JP8 option without opening the case, and something interesting, I added a USB interface as well as the PS/2 so I can use any keyboard. I had to dissect a USB to PS/2 adapter to understand what I had to duplicate, as the adapters are not just wiring.

Ok, inside you can see my internal wiring, its a little messy, but I did the best I could with what I had. I primarily used a small ribbon cable for the Radio and the Port A interface, because it isn't as bulky and I can bend it without causing problems.

I used the space I created with spacers on the screen module to route a few wires. I wanted the screen to be near flush with the case. I tapped the corner holes of the screen board and used small screws to mount it to the case.

You can see the battery pack I used, a plastic shell holding 8 Hybrid NiMh AA batteries. The Internal Power switch simply cuts off the power from the radio port pin 7, and connects to the battery pack. I had a bare ware problem with my construction that resulted in the batteries being charged in a very uncontrolled manner, destroying them, so I added a 1N4005 diode to each sided of the switch to control the direction of current. I later found my short, but left the diode to protect the batteries.

The TinyTrak4 board is a V7.1, which is the surface mount design. I used this so I wouldn't have as much trouble with the display interface, and was happy that Byon trimmed the fat on this board, making it smaller. I had to vertically mount the board in the case so I could still have room for the battery, but that caused a problem with seeing the LED lights. I solved that later.

For the keyboard interface, I found a neat PS/2 splitter cable, and after researching it, the standard PS/2 interface has 2 unused pins, and some manufacturers used the other pins so you can have a keyboard and mouse on one port via a splitter, pretty handy on laptops before USB. I trimmed some of the plastic of the keyboard connector so I could make it look good on the case. I cut off the mouse connector to convert it to the USB interface, and added 2 jumpers on the PS/2 - Screen board, pin 1-2 & 5-6, so I could bring the data from the mouse side of the splitter to the keyboard side.

I took apart a USB to PS/2 Adapter and discovered why my first attempt at a USB interface failed. The adapter has 2 4.7k resisters going from 5v to both the data in and data out pins, the keyboard would not start without these.






Note from Firmware Manual:
BNKMODE [ 0 | 1 ]
Sets how the desired bank is selected at runtime. 0 means no bank switching, and only use BANK 0. 1 means to consider JP1, where open means use BANK 0 and closed or grounded means to use BANK 1.


Now for the LCD backlight control. It is a little hard to see, but the first thing I had to do was cut the power to the LCD Backlight LED. I cut it between the PS/2 Connector and the pin connector. There is a tracer that goes to pin 15 and I just scrapped it with an Exacto knife. Now because the switch and display are both mounted to the case, I took power from the Pin 2 on the display, right before it goes into C4. Then I ran that power into a 1K Potentiometer so I can adjust the brightness. I discovered that with the screen running at full brightness, unmodified from the manufacture, the regulator on the TinyTrak4 gets pretty hot. When I was testing this out overnight, I still had the bare wire short to the battery pack, but the temp inside the case reached about 140, a little to hot for my comfort.

For the LED on the TinyTrak4 board, I took a small piece of plexiglass, and I made a 45 degree angle on one end, and used a silver colored Sharpie to help direct the light where I wanted. A rather lowtech approach but it works. No this wasn't my original idea, Richard at the local True Value gave me the idea, that's the reason I shop there instead of Home Depot. The weird dots you see is the mounting tape I used to mount the board vertically to the case. you can also see the wiring interface for the GPS Power switch. Its blurry, but the lower right is the wiring to the Config switch. When you set "BNKMODE 1", the unit will change from one bank to the other depending on if JP1 is shorted or not. See note from firmware.
Overall, I am pretty happy with the design. After using it for a while, I broke off the radio connector from the case, so I had to add the screws to hold them onto the case. During construction, it was fun trying to align the ports to the holes on the case, before the Crazy Glue set. Then scrap the glue mess from the port. I plan on adding a GPS module to it and attach it to Port B, so I can use Port A as a KISS interface or whatever, while maintaining GPS ability, that is the primary reason for the GPS Power Switch. I wanted to be able to turn off the GPS, when I don't want to beacon my location, but still monitor traffic.

The only thing I wish about this setup is out of my control. I can't use the calibrate function on this stand-alone setup, I have to play with the RXAMP settings if I swap radios. I have made a few suggestions for the way some of the data is parsed to Byon, like objects sent from a digi. I also suggested that he adds a menu so you can see a few objects relative to your location, and remember them like the Messages menu.

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KI6PSP (Ed)