Hardwired UB-Mite

Well, I did have a bit of time up my sleeve, and just couldn’t leave it alone.

 The top photo shows the upper side of the UBW32 mounted of a proto-board from Jaycar. The cable on the left is composite video to a monitor, top cable is the PS2 keyboard interface, power and USB connected on the right and you can see the SD card sticking out under the board on the bottom. The two red LEDs on the proto-board are as per the Maximite circuit.

The lower photo shows underneath with the point to point wiring and the SD card socket. The pinout of the SD Socket is, for the most, 0.1” and so it sits nicely on the board.
The SD card socket was salvaged from one of those multi-card readers designed to go in the 3.5” drive bay of a PC.
Maximite uses the UBW32 USB connection (mini USB)

No 26 way I/O socket or audio out yet.

A few notable notes….

All I’m really doing here is breadboarding the Maximite using the UBW32. All the necessary connections are on the 84 pins around the periphery of the UBW32. The UBW was fitted with two 40 pin single row headers, one on each side. I found some sockets for these for the proto-board, but you could just as easily solder the headers straight to the boards. I also found that the Jaycar proto-board holes were a little too small and needed enlarging to fit the pins
The Silicon Chip circuit diagram is incorrect in a few places which made the translation to the 100pin device a little bit harder… Geoffs diagram on his website is pretty much correct although I used SD03,SCK3 and SDI3 (as opposed to SD04,SCK4 and SDI4 on Geoff’s website circuit) for the card reader as per the Silicon Chip circuit.

All wiring was done using wire-wrap wire and a fine soldering iron. The SD-Card socket was fiddly but it worked first time!

The Maximite program switch needs to be in place and you use this to upgrade the Maximite Firmware over USB and ignore the switch(es) physically on the UBW32, except maybe the Reset if you get into a pickle.

Some pin translations to make it easier, this is in the form of Maximite=UBW32. Video out; SD02A=G8, OC3=D2, SS2A=G9. SD-Card; SD03A=F5, SCK3A=F13, SDI3A=F4

Also, also, also – the poor UBW32’s voltage regulators run really quite hot with supply voltages above 9VDC.

… and here is where I really will be leaving the hardware side of this project for two weeks. See you on the forum..

Here’s a picture of “Twinkle.bas” running on my monitor…

Maximite into a UBW32?







Firstly, apologies about the brevity of the following instructions, I’m a little time poor at the moment…

The Maximite (see Geoff Graham’s site here) is a great little Basic driven controller using the Microchip PIC323x processor. After reading the articles in Silicon Chip Magazine I decided to have a play with one.

What, too late, all sold out?! No stock until July or August?

After reading Geoff’s website, and he explaining that the Maximite Firmware (FW) would run in pretty much a standalone processor, I decided to have a look around and noticed the UBW32 from Sparkfun, why couldn’t I feed the Maximite FW into the UBW32?

Ocean Controls here in Australia had two in stock, so I ordered one. Which duly arrived the next day, I had a quick play with it and proved the UBW software was functioning OK. So I thought I’d try to download the Maximite FW via the UBW USB boot loader.

Na. Did not work.

The program loaded OK but would not run. I suspect the USB Bootloader and Application go hand in hand. i.e. you can’t use the UBW32 Bootloader with the Maximite FW. So I’d have to load the bootloader and Maximite FW via the ICSP programming header, to do this you need the Microchip PicKit3 programmer.

In the end it was really quite simple… load up the MPLab programming environment (this comes with the PicKit, but I have the latest from the Microchip website), set the processor to the 32MX795, Import the Maximite combined Bootloader and Maximite 2.1 FW and program it. I had my UBW running on a power supply during programming.

Suddenly I had Windows identifying unknown hardware on the USB port called “Maximite” this had to be a good sign!

The next step was to load the drivers for the Silicon Chip serial over USB link, and yes this is a different driver to the UBW32 one.

…and there it was the Maximite 2.1 Basic prompt in my Tera Term window!!

The next steps in a few weeks time will be to build some of the Maximite support hardware around the UBW, such as video out, SD Card reader, keyboard connection, etc…