I haven’t written in this journal in two months now. I’ve been busy with work, looking after my son, etc. But I have, in the past few months, squeezed in the odd hour here and there on my projects. I’ve managed to get quite a lot done, and haven’t really felt like updating this blog until now. This entry may… Read more »
I have, for about a month now on and off, been working on the controller board for the toner-transferring laminator. This involved buying some new tools including a drill press add-on for my Dremel multi-purpose tool, a chuck for the Dremel, and a collection of drill bits in various sizes. First of all, here is a picture of the finished… Read more »
Last Monday, April 28, the PCBs arrived. They only took a little over 72 hours door to door from Hong Kong. Pretty amazing service from DHL. And amazing service from Botech, who have done an excellent job making up my design. Here’s a picture of the five boards in their little wallet: And here are pics of the bottom of… Read more »
This last month or so I have been working on two fronts: finalising the circuit for the computer, and working on my home made PCB fascilities. So, the circuit is finished. For power the board has two options: USB, like the previous design, and a Molex harddisk power connector. Because of the high current sourcing with a PC power supply… Read more »
So, it’s been a bit of a mixed bag this month with the 6809 computer. First of all, I have decided to do the SBC “properly” and use a single CPLD instead of two. With that goal in mind, I’ve ordered a few parts: XC9572 in PLCC84 (3 of) PLCC84 sockets (4 of) Initially I wanted to buy some XC95108s…. Read more »
Though the previous PCB design was a vaguely useable computer, it required devices attached to an expansion port to be even moderately useful. A real Single Board Computer should be useful with just the single board. Combining a serial interface with an IDE interface should make the single PCB a computer in its own right, albeit one that only has… Read more »
First though, the integration of the seven segment display with the 6809 circuit. This turned out to be easier then expected. I added a bus driver component which replaces the counter to drive the mux, and in turn is driven (and drives) the databus. It also uses the read/write line and chip select control lines. The code for the bus driver is… Read more »
It looks like my problems with the counter were down to the 555 timer. Replacing the crufty old 555 with an Atmel ATMega8 generating the clock signal caused the counter to start working properly. Here is the ABEL code: MODULE counter // Defined inputs CLOCK pin 1;RESET pin 2; // Defined outputs Q3..Q0 … Read more »
So I have received the following goodies: XC9572 x 3 (PLCC44) Platform Cable USB programmer (Model DLC9G) Some PLCC44 PCB sockets (through hole) PLCC44 to DIP44 converter for the breadboard PLCC extraction tool The XC9572 is a simple part, by modern programmable logic standards. Not exactly capable of running a soft processor, the ‘9572 can still be used for one… Read more »
In my last post I mentioned the problems I’ve been having with powering my computer. A multimeter on various ICs shows a big drop across the power pins on some of the ICs. The AY 3 8912, for instance, was getting only about 3V. I have worked around these problems by using an additional power source to counter the voltage… Read more »