Wow, it's been three months since I last updated here, but that's not because nothing's been happening with the project - in fact, exactly the opposite! I've been so busy improving things and keeping up with the awesome stuff the community are doing that I've just not had time to write a log for a while!

For this log I'll just do a quick update on what's been happening over the past couple of months, with a promise to get better at keeping things up to date here on HaD. 

MC68681 DUART

Something that's always been a sticking-point for me (and for quite a few others now) is the 9600 BPS speed limit on the built-in MC68901 UART. As a step toward addressing this, I designed a whole-new comms board for the rosco_m68k, based around the (very capable!) MC68681. This brings two independent UART channels, the potential for future expansion with some additional IO ports, and makes uploading code to the system much less painful thanks to it's reliable support for baud rates up to 115.2Kbps. 

Even better, this is a drop-in replacement for the MFP UART, with recent revision 1.2 ROM builds supporting it out of the box (with auto detection). The board itself looks like this:

I talked a bit about the design in a previous log, but at that point the board wasn't generally available, and the code for it was nowhere near complete (beyond a breadboard design and a basic demo). That's all changed, and it's now available on Tindie :)

SPI & LCD Awesomeness

There's been a lot of development lately around getting bit-banged SPI working, using the GPIOs provided by the MC68901, and @Xark changed the game by implementing some new SPI routines that were >5x as fast as the ones we had before. Not content with that, he went on to use his new SPI routines to implement an awesome bit-banged SPI LCD slide-show for the rosco_m68k! 

The code itself is awesome, but the video shows it even better:

That's right - this is a 16/32-bit m68k system pushing full-colour images out over SPI via the (almost forty-year-old) MC68901, all driven by some super-optimised hand-crafted assembly SPI routines. Totally awesome!

(In other news, Xark also became the first committer on the project who isn't me, and has already made some great contributions!)

SD Card Support

Hot on the heels of Xark's SPI stuff, we were able to revisit the SD Card support, specifically using the faster SPI routines to get a decent speed boost. 

It's early days yet (the code is still sitting in a PR but will likely be merged by the time you read this) but it's looking pretty good - SD support is in the development ROMs, with an SD loader, pretty-complete FAT support (thanks to ultraembedded's FAT library) and support for SD filesystems in user code via a new standard library.

And more!

There's been so much more going on that I haven't mentioned here - expect an upcoming post about a totally awesome front-panel project, a brand-new but very promising OS, and tons of other stuff. And this time, I promise it won't be three months before I do those posts!