AMD, Vantis, Lattice CPLDs

Many years ago in a far distant galaxy... I bought from AMD the MACH CPLD starter kit, it was small experiment board and a parallel port ISP programmer. Since then the company changed name once and was bought by Lattice. The software "Design Direct" ran in Microsoft Windows 95, I managed to make it work in XP despite the hard disk serial number protection and I've been using it with a MACH131SP for the USBKeyboard.

The reason I'm using the MACH131SP is because last year I bought a box of about 100 in Ebay, so now I have "stock" for the years to come... I had to buy an adaptor for the TQFP 100 in order to WireWrap a simple circuit, the one in the picture was bought in Japan. I soldered the CPLD by hand, it is not very dificult but you need a good soldering iron, good solder, a clean board and a steady hand.
The circuit included a 78L05 to regulate the supply voltage, but I had to bypass it since the CPLD consumes 75mA and the 78L05 limit is 100mA. With most of the inputs floating the CPLD forces the 78L05 into foldback and quasi-shutdown.
The other connector is the 10 pin In System Programmable connector (JTAG), from it I can program a plurality of devices in a JTAG chain.

For connecting power and the ISP connections I used Wire Wrap technique, while for the USBKeyboard circuit I used a special enameled wire. With the Wire Wrap soldering the pins is not mandatory as long as you use correctly the wrapping tool. With the enameled wire a special pen is used to lay the wire, wrapping around the pins you need to connect and then solder must be applied for some time (and temperature) breaking the enameled protection and soldering to the pins.

Mini85 has left the building...

I decided to dismantle the Mini85 circuit to gain some desktop area for the next year. It was the biggest and more complex breadboard project I've ever done. I did not manage to build it in three standard breadboards, but I still find it small enough. With a single PAL (maybe a 16V8) I'm pretty sure it could fit the three boards.
The next step is use what I've learned from this Mini85 project add it to the PCB design and USBKeyboard and build a eurocard (100x160mm) CP/M computer.
Here is his last picture in this format...Mini85 "will be back" soon... in PCB format...


Joules thief circuit

Last weekend I started some experiments with the "Joules thief" circuit. The circuit is very simple to make and it should work first time, if not exchange the connections of one of the windings. It works down to 1.2V but it probably works down to 1V. It should be possible to design this circuit with higher efficiency once some of the circuits components are better defined.
Here's a picture of my Joules Thief circuit with a white LED...Some parameters can be determined experimentally, like saturation of the inductor (max ampere turn), gain of the transistor, the frequency of oscillation can be controlled with a capacitor on the base circuit. I've also experimented with a solar cell powering the circuit, but the it needs to be under a strong light.
One of my project ideas was to build an "daylight extender" with a two or three white LEDs, a Ni-Cd battery and a light sensor, maybe with a microcontroller.

Christmas, Winter Solstice and Chili pepper

Christmas is coming soon! Yesterday were spent the afternoon baking cookies and looking for some last minute presents. Every present is now wrapped and ready to pack. I still have some important things to do in the run up, like cleaning and a major overhaul of the bike(s), packing, cleaning the house etc., but with decent planning we'll be fine!
Today is the winter solstice, the shortest day (daylight) of the year! It is time to celebrate... From now on the days can only get bigger, although it can still get colder... brrr.... It is also the start of the Winter season! We already had the first snow fall in late November, but with only two centimeters of snow... maybe later it gets more interesting.
And now for something completely different...
Our indoor "three vase garden" has been going on. We planted parsley, basil and chili peppers in three vases before this spring. This year, Spring was actually quite warm but Summer was pretty lame, and although our plants grew and some flourished (basil and chili peppers) they did it quite late in the summer. Mid September I had to take the vases indoor as the conditions outside deteriorated. When inside I tried some hand pollination (as I have no bees or flying insects at home) with a cotton bud and as a result I managed to get some basil seeds and to my surprise, one chili!

This week it changed color! it has gone red! I have some projects to extend the light time and control the moisture in the earth, something similar to the garduino project ... but more autonomous and without a full blown arduino and minimal feedback to the user.


Creating a PCB with gEDA

I always wanted to try out the gEDA tools for producing PCBs and schematics in the Linux environment.
The ongoing mini85 (8085) project is to big for a first try, there are many packages that are not standard in gEDA, many schematic symbols that also do not come standard, there are many ICs in the schematic, these are too many variables to control for a first time.
I needed something smaller, where I could fully test the tools. I decided to use my USBHID Flight simulator control for this project. I would also try out other things like adding a MACH131SP because it is a SMD component, programmable via a ISP connector (also test the software) and test the package outline of a DB9 connector, the power connector and USB B connector.
I want to send the board for fabrication, most of the PCB fabrication houses need a gerber file (none accepts pcb format), but not many details appear in the official tutorial.

The schematic editor has a reasonable sized library, but if a symbol is needed the procedure is quite fast, I used tragesym and the tutorial is here. I redesigned the symbol for the Atmel AVR AT90S2313 (also ATtiny2313), because I prefer to have direct access to the VCC and GND pins and I don't like the crystal oscillator and the reset input in the bottom. Here is the first page of the schematic.

For converting to PCB I downloaded a library from jluciani, it seems very complete... I still have to understand how to use it properly and in conjunction standard libraries. It needs a small modification of the command line of gsch2pcb.
gsch2pcb --use-files --elements-dir ~/footprints SCHEMATIC_NAME

For now I think the footprints provided are suficient, but I'll probably need to draw new footprints for some older PGA microprocessors (when the time comes)...
Another way will be to try the same system with kicad, it also appears to be a good (free) design tool for linux. It has an extra that for now I don't really need which is the 3D view, but who knows latter...