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RaSCSI Development Thread

landoGriffin

Well-known member
Another pull request out there! I figured out what was wrong with my "FULLSPEC" version of the board. Did you know that if you flip the connector, things don't work?  :(

https://github.com/akuker/RASCSI/pull/24

Changes include:

- Fixed the Rpi and DB-25 connectors that were flipped

- Removed LEDs for the Terminator Enable switch (I didn't think these through when I originally put them on the board... they didn't work the way I thought they would)

- Added header for the "spare" GPIOs so that external LEDs (or whatever) can be hooked up to them

- Added a 5v/GND header

- Copied some silkscreens to the bottom

This is the board I'm going to build up a ton of them, so feedback is welcome!! (Note: I did fix the overlapping silkscreen on the back, but was too lazy to re-create the images)

image.pngimage.png

 

motosega

Member
Wow I'm really impressed by the work you guys have done!

I bought a raspberry pi when I first saw rascsi, but It looks like the quick and dirty diy version without bus transcivers has a few problems, so I was planning to make a PCB eventually.

I'm really glad I didn't have to though, because it looks like this is much better than I could have done by myself. I've only made a few boards with kicad so far.

What's the plan with the fullspec version? I'm dreaming of a Linux scsi host driver, since I also have Akai samplers that use SCSI,  these samplers have Mac and pc based software (MESA) for gui sample editing, I currently have to maintain an old PC for this, which i'd happily replace with a Linux based system or an emulated Mac.

it looks like the web interface will be perfect for loading sample CD images into my samplers, I have a huge collection of Akai CD images, up till now I've been copying them to zip disks, but it's not practical since each CD spans several zip disks.

In my Mac classic and LCII the baremetal version would be great, but the prospect of a scsi-ethernet interface is tantalising.

When somebody has boards ready and tested I'm interested for sure.

 

landoGriffin

Well-known member
What's the plan with the fullspec version? I'm dreaming of a Linux scsi host driver, since I also have Akai samplers that use SCSI,  these samplers have Mac and pc based software (MESA) for gui sample editing, I currently have to maintain an old PC for this, which i'd happily replace with a Linux based system or an emulated Mac.
fullspec version should be coming soon! With any luck, should be able to start shipping some out early/mid September.

Different topic..... If you assemble this thing the way I'm envisioning, you won't be able to access the power connector with a Pi Zero. So, I'm thinking of adding a micro USB port so that you can still power the unit. (Can anyone say "scope creep"???)

Very crude mock-up shown here....

image.png

 

PotatoFi

Well-known member
Dumb question: Can the Raspberry Pi not be powered from the SCSI bus? Forgive me for not combing through the thread to find the answer.

I have powered Raspberry Pi's from the GPIO's many times over the years... so I am personally not too concerned about the USB port on the Pi being blocked. If It did need to be powered via MicroUSB... I wonder if some power could be pulled from an ADB port.

 

landoGriffin

Well-known member
I suppose I could just put a 90° pin header on the pi zero.
It would have to be a super low-profile cable. There really isn't much space there.

I updated the board to add a micro USB port on the side. I swear, I'm done tweaking things now :)

image.png

Dumb question: Can the Raspberry Pi not be powered from the SCSI bus? Forgive me for not combing through the thread to find the answer
Not a dumb question, and I don't blame you for not combing through the entire thread! Its getting pretty long!

I think that could work, but the way things sit currently, the Pi need to be powered on before the Mac it is connected to. I'll have to try that some time and see what happens. 

 
Hi landoGriffin,

I've been reading about your work today and that is very impressive. I was wondering if there is plan to sell the set (PCB+Components) or if you guys recommend a provider.

I've got a Macintosh SE and RaSCSI sounds very promising.

Thanks heaps!

:)

 

landoGriffin

Well-known member
Hi landoGriffin,

I've been reading about your work today and that is very impressive. I was wondering if there is plan to sell the set (PCB+Components) or if you guys recommend a provider.

I've got a Macintosh SE and RaSCSI sounds very promising.

Thanks heaps!

:)
Hi Somique! I should have some to sell in 3-4 weeks. Stay tuned :)

 

jammi

Active member
Different topic..... If you assemble this thing the way I'm envisioning, you won't be able to access the power connector with a Pi Zero. So, I'm thinking of adding a micro USB port so that you can still power the unit.
So, couldn't you just use the 5V pin on the GPIO header of the Raspi to power it? That's what I do with most of my Raspis.

 

jammi

Active member
Yup. You definitely could. But, I like a micro USB connector better  :p
I also guess termination power isn't enough to power a raspi even in some underclocked low power mode? Because if it was enough, you could just power it like that without any extra USB thingies. I'd also vote for a USB-C connector if you go the USB route, since those will be more plentiful soon. Micro-USB will be the rare thing you never find a working cable for just like the Mini-USB is now.

 

uyjulian

Well-known member
I think it would be possible for terminator power. However, as mentioned before, the Raspberry Pi needs to be up first before the Mac.

Powering the Raspberry Pi using the terminator power would be possible if the Mac has a lot of RAM, and thus takes a while doing the RAM check, giving time for the Raspberry Pi to start up.

 

landoGriffin

Well-known member
I'd also vote for a USB-C connector if you go the USB route, since those will be more plentiful soon
Unfortunately I already ordered a bunch of Micro USB connectors. :/

Good news though.... A bunch of Version 2.2 boards (Fulllspec) are ordered and should ship from China this week! Once I check them out, I'll have more details. 

 

jammi

Active member
I think it would be possible for terminator power. However, as mentioned before, the Raspberry Pi needs to be up first before the Mac.

Powering the Raspberry Pi using the terminator power would be possible if the Mac has a lot of RAM, and thus takes a while doing the RAM check, giving time for the Raspberry Pi to start up.
It could also operate from a small battery and go into some sleep mode whenever it's out of termination power and could have some "ready" led when it's booted and running. Therefore, it'd sense the termpwr as a wakeup signal and be ready in a fraction of a second while the Mac is still doing its POST. The battery could also balance the power consumption so it can rely on something that termpwr on average can provide.

 
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