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RaSCSI Development Thread

K55

Well-known member
Figured I'd get this one started. I've just finished up the board design for an implementation for the RaSCSI device as seen here http://www.geocities.jp/kugimoto0715/rascsi/index.html

Schematic:

sche.PNG

Board:

rascsi.png

Sorry about the messed up wires on the top, had to re arrange stuff to make the board layout easier.

This design is going to use the 4 74ls641s. They run about $3 each and with everything else + pcb; $20 would be the at cost price.

If anyone's interested I'll be ordering 10 (ish) copes tomorrow. I'd probably sell for around $30ish.

The one benefit for this over the scsi2sd is that I think a raspi is more accessible and available to people than the other SCSI emulators on the market,

and that this can be updated with new GPIO updates etc, and improved in software. |)

 

K55

Well-known member
Side note this is the schematic I worked off of (in case it gets deleted):

cable4.png

cable1.png

SCSI pinout:

scsi.PNG

 

defor

You can make up something and come back to it late
Staff member
This design is going to use the 4 74ls641s. 
Glad to see you using SMT instead of DIP

Two suggestions:

- Add a second set of board mounting holes that aligns to the Pi, to allow for spacers to keep the SCSI pins from getting anywhere near the conductive surfaces of the HDMI port and similar.

- Use a right-angle SCSI connector such that this actually might be able to be mounted somewhere where a HDD might fit that has cable clearance out the back, but none to the top.

 

K55

Well-known member
V1.1 Update: now has 4 headers and a molex connector for power from the mac itself.

rascsi1-1.PNG

Edit: This would work as long as you had enough clearance for the SCSI plug. I'm going to work on a right angle version but it'll probably push up the cost a dollar :cc:

 
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Trash80toHP_Mini

NIGHT STALKER
Beautiful! Another suggestion: use an ISA floppy/Zip power connector instead of MOLEX to keep the profile low. MOLEX connections are at a premium in Macs and FDD power takeoff/splitter cables seem to be a bit more compact/shorter.

 

defor

You can make up something and come back to it late
Staff member
A little confused about the placement of the second set of mounting holes as they don't seem to line up with the PI mounting holes, or am I mistaken?

 

K55

Well-known member
They're holes for the zero model, that's the aim anyway. I can fit in the regular holes, but its 2am and Im tired

V1.2 with a right angle connector, had to rework the entire board, also switched to the mini 4pin floppy (thanks jt)

rascsi1-3.PNG

 

K55

Well-known member
V1.3 With full size mounting holes. Still have to add some compact mac artwork, and fix the ground planes, and we should be done~~~

rascsi1-4.png

 
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Trash80toHP_Mini

NIGHT STALKER
LOL! I've already bounced another LED hack off K for that nifty little bit of prototyping real estate! Thanks for the suggestion, SMT LEDs right on board with a one piece printed coverplate might work out great for it.

 
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joethezombie

Well-known member
That's really cool. Put my name in for one. Can I ask what software you use to create these board layouts? I kind of want to get into hardware design, but don't know where to start with the software.

 

olePigeon

Well-known member
LOL! I've already bounced another LED hack off K for that nifty little bit of prototyping real estate! Thanks for the suggestion, SMT LEDs right on board with a one piece printed coverplate might work out great for it.
:D  Well, I designed the Jolly Roger that's used on a couple homebrew projects.  Since I'm a liberal arts major, it was the only thing I could contribute to these awesome projects.  So far, DougG3's original SIMM is my favorite implementation with the glowing red LED eyes.  It's just too cool.  I'd love to get a proto-clear lid for my IIci so I could see it all the time. :p

 

olePigeon

Well-known member
Does this have to be connected to a Rasberry PI?  Or can it work like a SCSi2SD?  Can I update it without a Pi?

 

Trash80toHP_Mini

NIGHT STALKER
I love the red glow of mine too, but when I'm around them my boxes the hoods are almost always popped. Love your design. Workin' on a Clear IIfx lid, got access to a CAD/CAM milling rig?

Liberal arts major here too/fine arts minor, it's not a bug it's a feature! Also frees the mind from conventional fetters, especially at a Jesuit school! ;D

 
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K55

Well-known member
Does this have to be connected to a Rasberry PI?  Or can it work like a SCSi2SD?  Can I update it without a Pi?
Its made to work with any pi B+ fowards, so the 2,3, zero etc. Makes things flexible.

We'll see about software once I get the HW in and can work with the original dev's drivers.

JT would breakout points for the activity led be ok with you?

 

defor

You can make up something and come back to it late
Staff member
I personally wouldn't even have bothered supporting the zero, considering how slow it should be, given the 1MiB/sec was measured off a Pi3, and GPIO speeds are bound to the cpu speed, but who knows....

I'm working on a different style project using RaSCSI so don't worry, I won't be overlapping once I get my pcb finished- put me down for one of your boards as well though.

 

Trash80toHP_Mini

NIGHT STALKER
Sure, just put in thru-holes for header pin installations for:

Power 5V & 3.3V are available on the board, correct?

HDD Activity

Fill up the added real estate on the side with a prototyping area just for kicks.

Breaking power and HDD activity out to a header will give oP the chance to print up some 3D skull-n-pistol sticky badge dongles for his LEDs. Put the Logo Dongle on wire wrap wire and thread the leads out through the power LED light tube opening and he'll be a happy camper.

Somebody can figure out how to drive 'em at 3.3V/whatever whenever the computer is on then and kick 'em up to the full 5V whenever there's a disk access blip fed to an adapter circuit in the proto area. Maybe just a couple of gates? He'll be friggin' thrilled. [:D] ]'>

Do I see any mechanism for SCSI Drive ID settings?

 

K55

Well-known member
Sure, just put in thru-holes for header pin installations for:

Power 5V & 3.3V are available on the board, correct?

HDD Activity

Fill up the added real estate on the side with a prototyping area just for kicks.

Breaking power and HDD activity out to a header will give oP the chance to print up some 3D skull-n-pistol sticky badge dongles for his LEDs. Put the Logo Dongle on wire wrap wire and thread the leads out through the power LED light tube opening and he'll be a happy camper.

Somebody can figure out how to drive 'em at 3.3V/whatever whenever the computer is on then and kick 'em up to the full 5V whenever there's a disk access blip fed to an adapter circuit in the proto area. Maybe just a couple of gates? He'll be friggin' thrilled. [ :D ]

Do I see any mechanism for SCSI Drive ID settings?
ID is set in software, still looking at the software side, will probably understand it at some point, SCSI isn't that complicated :p

V1.4: Added in breakout header for JT, tided up some minor errors, and added in snazzy artwork. It's probably done at this point, so I'll order it tomorrowish and expect it to be here the 1st week of june approx.

rascsi1-4.png

 
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