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RaSCSI Development Thread


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On 8/19/2020 at 3:17 PM, landoGriffin said:

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.

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23 hours ago, landoGriffin said:

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.

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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.

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13 hours ago, jammi said:

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. 

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10 hours ago, uyjulian said:

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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Also... FYI for everyone.... The boards are being made! Once I get them, I'll probably throw them on Tindie to help distribute them.

image.png.06dec94efee8efb4ccee36e2cbdaf195.png

(Note: these are only PARTIALLY assembled. Only the teeny tiny surface mount parts are being installed by JLCPCB)

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8 hours ago, landoGriffin said:

Also... FYI for everyone.... The boards are being made! Once I get them, I'll probably throw them on Tindie to help distribute them.

 

(Note: these are only PARTIALLY assembled. Only the teeny tiny surface mount parts are being installed by JLCPCB)

Sounds good!  Will you include the other components in a kit form or do we need to order these separately?

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FYI: I've updated the github build to use the ARM cross compiler for building RaSCSI. The makefile also defaults to using the gnueabihf arm compiler. Before, it would use whatever the host environment is.

 

This doesn't matter for most people - but I do some development on a x86 PC for stuff that doesn't require the real hardware. The socket/command interface still works on non-RaPi devices. It just doesn't do anything useful :p

 

I hope everyone is having a good week! I've been checking jlcpcb every hour, waiting for my bulk order to ship! Once they get here, I'll have them up on Tindie if there are still folks who are interested in them:

https://www.tindie.com/products/landogriffin/rascsi-macintosh-version/

(That link might not work immediate... the product listing is still under review)

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I want to try this on a Roland vs audio workstation.(VS-1680) It has an external scsi bus. Does anybody know how much cpu is used on a pi3 or pi4 when running Rascsi?

I'd like to be able to use the spare cycles to convert the files from propietary roland format to stand wav files if there is sufficent cpu time available.

 

I've also got a Mac SE, I'd like to try it in....

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The bulk of the work is done in a single thread, so the RaSCSI service will be limited to one core. On the Pi4, that would leave you with 3 cpu cores to do other things. 
 

You might get some contention for disk access though. Depending on how much data you’re talking about, you’ll probably be fine.

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10 hours ago, sixty80hforty said:

I want to try this on a Roland vs audio workstation.(VS-1680) It has an external scsi bus. Does anybody know how much cpu is used on a pi3 or pi4 when running Rascsi?

I'd like to be able to use the spare cycles to convert the files from propietary roland format to stand wav files if there is sufficent cpu time available.

Does it use a normal FAT file system that can be read on a computer? I think a lot of old music gear like this had proprietary file systems. Probably a simple one, but I think there'd be some coding needed.

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On 8/23/2020 at 4:43 AM, uyjulian said:

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.

I see the appeal to have it powered by the SCSI bus, but I don't see how it can be done practically.

 

The Mac II, SE and Plus use an NCR 5380 SCSI controller. The controller outputs have a max voltage of 2.4v, and 48mA. In addition to the low numbers, the SE, Plus and II don't provide termination power.  Even if there was a way to scavenge power from some of the other lines, The Pi Zero W needs at a minimum 80mA, and to get the power draw that low, you sacrifice a bunch of functionality.

 

I think powering stuff via the SCSI ports would hinges on termination power being available. But since the computers this is initially targeted at target machines don't provide TERMPWR, building any circuitry to leverage it, and building a environment to boot up quickly would yield very little gain.

 

What could be useful is a separate unit, something akin to a parallel port pass through dongle type thing.  It could scavenge the TERMPWR and feed it into the RPi via an external cable, or whatever. With a separate unit, it's modular, and could be used for this or any number of other projects.

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