General Category > LisaList2

An Arduino-Based Parallel Port Hard Drive Troubleshooter

<< < (6/10) > >>

stepleton:

--- Quote ---You might be good now, but it means you can't upgrade this thing or add much else to it. So it's gonna be a dead end. Might want to consider the next model up.
--- End quote ---

I think I'm more optimistic than that!

The Lisa will eat up all your cycles while it's talking to you: ~PSTRB is a pretty demanding boss. But in between some well-defined and limited parts of the read/write cycle, the ProFile can sit there holding down ~PBSY while it thinks, and the Lisa will just have to wait or decide to time out.

The thing is that you've already implemented all of the really time-critical parts by now, and all of the bells and whistles that you might want to add (e.g. Selector compatiblity :D ) are things that the Arduino will do while ~PBSY is asserted and the Lisa is waiting. I think the little microcontroller will be able to accomplish a lot in those intervals. Sure, it'll have limits --- it won't be able to run Doom in the background and send dithered bitmap frames down the parallel cable for the Lisa to render on its display, something which is definitely not a gimmick I've been thinking of doing for months on Cameo/Aphid --- but virtually all "reasonable" extras should be doable, i would think.

AlexTheCat123:

--- Quote ---The thing is that you've already implemented all of the really time-critical parts by now, and all of the bells and whistles that you might want to add (e.g. Selector compatiblity :D ) are things that the Arduino will do while ~PBSY is asserted and the Lisa is waiting.
--- End quote ---

Exactly! Any additions that I make will take place at times when we can hold BSY low for pretty much as long as we want and I won't be adding anything to the time-critical sections, so as long as the Arduino can reliably handle these timing-intensive sections as they are now, it should be able to handle things like Selector compatibility that I add later.


--- Quote ---You might be good now, but it means you can't upgrade this thing or add much else to it. So it's gonna be a dead end. Might want to consider the next model up.

--- End quote ---

I was originally planning on using a more powerful microcontroller, like the Teensy or ESP32, but I decided to stick with a slower Arduino Mega because the Mega uses 5V logic levels and all of the faster offerings use 3.3V levels. One of my major goals with this project is to minimize the cost and complexity of the device and eliminating the need for level shifting definitely makes the hardware cheaper and simpler.

Once I figure out the strange 5MB problems with LOS, I'll get started with adding Selector compatibility. It seems like it will be pretty straightforward to implement, although the SD card library that I'm using only supports 8.3 filenames, so I'll have to figure something out there since the Selector lets you use names that are much longer than this. Maybe I'll need to find a different library that can handle longer names!


--- Quote ---it won't be able to run Doom in the background and send dithered bitmap frames down the parallel cable for the Lisa to render on its display, something which is definitely not a gimmick I've been thinking of doing for months on Cameo/Aphid
--- End quote ---

You should totally do that! It would be so cool to see Doom "running" on the Lisa!

AlexTheCat123:
It's finally time for another update on the ArduinoFile! I've implemented almost complete Selector compatibility, which really increases the usefulness of the device. The only things that I don't have working are modification dates when the Selector asks for information about a file (I can't get the getModifyDateTime() function in the SDFat library to work properly for some reason), the uptime counter, and the key-value store (I'm not looking forward to implementing that one).

I should hopefully be able to get the modification date and key-value store working, but the uptime counter is a bit of a lost cause. Since I have to keep interrupts off throughout most of the code to keep things fast enough, I have no way of accurately tracking the passage of time since the millis() function only works when interrupts are enabled. The Selector seems to send emulator status requests once every two seconds, so I've just settled for incrementing the uptime by 2 seconds each time we get a status request. This solution isn't ideal because the uptime will stop incrementing whenever we're not in the Selector (or when the Selector's screensaver activates), but it's better than nothing.

I just put the ProFile emulator code on GitHub if anyone's interested: https://github.com/alexthecat123/ArduinoFile

I also just finished designing a much more compact PCB that stacks on top of the Arduino, much like the Cameo/Aphid cape for the PocketBeagle. I've added a status LED, a reset button, and the LS280 parity generator to the board and I'll put the new board design on GitHub once I get the boards in the mail and test them.

stepleton:
Congratulations on your progress, it sounds really impressive! I had wondered how things were going.

The uptime counter is not very important at all --- like the manual says, "It serves little purpose except to look 'geeky' and to demonstrate that the Cameo/Aphid is operating and responsive." If you ask me, since it can't really keep time in a meaningful way, and since keeping time isn't very useful, you ought to make it count backwards ;D Or just animate it some other way, like


--- Code: ---0d 00:00:01
0d 00:00:10
0d 00:01:00
0d 00:10:00
0d 01:00:00
0d 10:00:00
1d 00:00:00
--- End code ---

I think the Selector's rate for pinging the uptime counter is a bit faster than once every 2 seconds, but I've never timed it.

I don't know how to solve the modification time problem, but for the key/value store I'd probably just hijack the filesystem on the SD card in some cheap and cheerful way. You'd have to be careful about some characters that you're not allowed to use, and I guess case sensitivity could be a problem, but otherwise it's kind of a key/value store already...

AlexTheCat123:
Update: I finally got the revision 2 PCBs in the mail from China and they seem to work great, so I've updated the hardware section of readme.md to provide links to all the parts needed for this project and I put the new board files in the PCB folder. Now that there's a parts list and a fully functional PCB, people should actually be able to make one of these!

https://github.com/alexthecat123/ArduinoFile

Navigation

[0] Message Index

[#] Next page

[*] Previous page