Here is another project from Byonics, The PeekPack. This little unit allows you to monitor packet activity with just it and a radio, even a scanner. It makes use of a 16F84 PIC and a MX-614 modem chip to receive, decode and display the packet. So far, it only shows the orginating callsign, the destination callsign and up to 16 bytes of the packet data.
So far this is only an experimental project, build at will. I have talked to Byon about this many times and he say that the HEX code is the basic beginning and he plans to add things such as NMEA string decoding and scrolling text. The schematic is basic, but enough for now. The additions are all in due time. The only thing I did'nt ask him was if he planned to make this into a kit to buy. I'm crossing my fingers, even though I had fun building one on my own, I would like to build the kit also. I still plan to design and etch my own PCB for it.
This is the LCD I used for the PeekPack. Its a simple 2x16 from a wonderful company Crystalfontz. They produce high quality display at a VERY cheap price :o) It uses the industry standard chip set Hitachi HD44780.
This is a close-up shot of the MX-614 modem chip. It's available from TAPR for about $6. This chip is what makes the PeekPack so handy, no external TNC. Very small too, only a 16 pin DIP.
Here is a close-up of the 16F84 PIC. It's an 18 pin DIP. This is bascially the heart of the unit, since it holds the firmware that controls the whole things and it does the packet decoding. The little white box to the top left is the 10 Mhz resonator. I used the resonator with built-in caps, less parts. These, along with almost everything else is available from Digi-Key.
I saved the power supply section for last since it's the most common element of the circuit. It's just a 7805 5 VDC regulator and 2 0.1 microfarads, one parallels the input to ground and the other parallels the output to ground. These filter and regulate the power supply.
Once I finally got the PeekPack to work, I was able to view the packets running around in my local network. WB4QOJ-2 is an APRS digipeater in a neighboring city. IT WORKS!!! Except it only works with audio input from a mobile's ex speaker jack, which tells me that it requires a very high level of input volume to drive the MX-614 chip. The HT did'nt cut it, none of them did (6 different HTs).
I think the next step is to add a small amp stage to boost the input audio.
This is what I'm thinking...
But, before I go and build that, I thought it would be fun to go ahead and make an etched board for the original design (below)
I sized the PCB to the same size of the LCD's board that way I can stack the whole thing together and just use threaded stand-offs. The LCD will connect to the processor board with a simple header strip, that way it can be taken apart in modules.
Here is the final version of the original design, PCB and all. What PCB??? It's underneath the LCD, slick huh? :o)
This is a close-up of my peek pack. I can't beleive how well it turned out, as small as the LCD's PCB. Nice small little package.
Here is just a picture of my Peek Pack with an old Standard HT and the 9 VDC battery the Peek Pack runs on.
Here is a shot of the connections from the processor PCB to the LCD. I know I specified a single line header, but I got anxious and could'nt wait on Digi-Key to send me one. So, I used some standard breadboarding jumpers. I'm sure I'll replace them later with an actual header. But these worked just fine to get it together and test it.
Here I just un-folded the stack to show all of the components or "goodies" on the PCB laying under the LCD.
And here is some shots of the copper traces on the PCB for the PIC, MX-614, ect. The PCB was made with good ol' copper clad board, rub-on tranfers from RadioShack and Ferric-Chloride Etchant (heated and agitated every few minutes). In the layout process I made two mistakes :o( Mistake "A" is I did'nt leave a trace for the ground to audio in (what was I thinking?). Mistake "B" was I did'nt leave a trace for Vcc to get to the PIC and the MX-614 chip (I deserve a beating for this). Both mistakes were taken care of with some jumper wire, wire-wrap wire would have been fine but I used some breadboarding jumpers for a little more strength. I have some more parts on order and I plan to re-build a second version and this time get the traces right. I need to re-map some, but not all. Hey Byon, if you are looking for a PCB to use in kits, I would be glad to submit (after the revisions of course) :o)
What's a project without a project box? Well, to make my Peek Pack look a little more "pro" and also to protect the PIC and MX-614 chips from static I mounted the who unit in a small RS project box. Inside some basic nylon standoffs from Digi-Key were used to mount the whole module to the front of the box. Inside I took the 9 VDC battery and wrapped it in some scrap cloth to keep it from bouncing around and to keep it's metal case from shorting anything out on the board. I use a good ol' ruler and pencil to measure my dimensions for the LCD cut-out. I then just scored each run with a sharp X-acto kneif and then punched it out leaving a pretty nice edge.
Here on the end of the box you can see that I mounted a SPST toggle switch for power and also a 1/8" mono-jack for the audio in. You can also see some other holes from a past project this bx came from. The project did'nt go the way I thought it would, oh well, just re-use the box for somthing else.
Some final thoughts for now. I really enjoyed building this project. I'm 20 and the only experience I get is the projects I take on, on my own. I epecially love when all I have is a good ol' schematic and a handfull of parts I had to dig up on my own. Kits are for conveince and made to be built worry free and quickly. Projects like this need to taken for the fact that somthing may not work and you may have to play with it to get it right. I really like how stable the firmware is so far. I had mine running for about 3 days straight without a problem. I'm looking forward to when Byon adds scrolling and the other features he mentioned adding.