Simon Frankau's blog
Electronics for Newbies: SD card access
And again, another year since my last update on Dirac. Since then, I've done a few different projects, including building a VGA-generating circuit and reading data from a floppy drive.
On the Dirac front, I've mostly been doing software things, specifically learning about and fiddling with CP/M. It looks very much like a I should be able to port it to Dirac. However, I will need to have some kind of mass storage. So, I've added SD card access hardware to Dirac.
This is a lot less exciting than it sounds. I've finally wired up the parallel port chips control lines. Then I plugged a few pins through to the SD card breakout board, and off we go. It was made a bit more tricky by having to do 5V - 3.3V conversion, and basically running out of space on the breadboard, but now it's done!
There are updates to the schematics, docs and code on github. So far, I've really focused on getting the hardware together, with minimal software to test it. From here on out, this should be pretty much a software project.
Resource-wise, there are a couple of good pages about how to do SD card interfacing, which are dead useful. Interfacing in SPI mode looks extremely plausible.
The remaining physical-side effort is not electronics, it's getting a case. So far, I've survived with a bare board, but I really need to prevent it from getting damaged now that it seems to be working. I suspect a custom laser-cut plywood box would be appropriate.
Posted 2016-06-05.