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MrGasS27

Cloning SCSI2SD... Is it an Impossible Mission?

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"Another visitor, stay awhile, stay forever!"

Okay, I was joking about the C64 game, "Impossible Mission" is referred to this idea.

 

Hi everybody! :)

So, I'm an happy owner of SCSI2SD v5 board, I use it in an external box, it works great and I use it on every SCSI Mac that I have, but they are too expensive in my opinion: I want to produce 2 boards for my childhood's lovely Macintosh IIsi and my PowerBook 145B, the 2.5 board "PowerBook edition" is more expensive than the 3.5 one so, why don't try to clone it? Obviously I clearly know that isn't an easy thing but giving a try isn't a bad thing...

 

On GitHub (https://github.com/vivier/SCSI2SD) I found SCSI2SD v4.2c (3.5") and v4.1 sources (2.5") with Gerber files and Cypress Creator's sources for the building the firmware.

I spent 2 days thinking about building the SCSI2SD's firmware and yesterday evening I built it with Cypress Creator, now I have 2 ELF and 2 HEX files and the question is: how to push the Bootloader and the Firmware HEX files to the CY8C5267AXI-LP051?

 

The Cypress LP5 PSOC that SCSI2SD uses supports JTAG/SWD protocols for programming, so, the best programmer for this PSOC would be the MiniProg 3, but it's too expensive (circa 88$), and here it is another question: what would be a "cheap" JTAG or SWD programmer for programming the LP5? Is this PSOC reprogrammable in case of bad HEX files? (I think yes, but I even want to ask)

 

Soldering SMDs component and the IC isn't a big problem for me, I did everything with my soldering station and I soldered a lot of SMD component in my life, the difficult thing for me is programming the PSOC.

 

Please, don't blame me, I repeat, I clearly know that is a very difficult thing, I also know that RaSCSI exists and it's the easiest thing to do (I also tried it with my Q700) but I want to give a try.

 

Thank you :)

 

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Edited by MrGasS27

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You have to get the bootloader on there first. Thats bare minimum, when thats in place I think you can stick the main application image on the SD card and itll update the firmware, I think. Or it might be via the USB setup software he provides that can. 

 

But a JTAG is an absolute necessity if you want to flash a blank chip. Bootloader is a minimum. 

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I'm buying the Segger J-Link OB for flashing the LP5 via SWD on Eclipse, I have only to export the Cypress projects to Eclipse (because Cypress Project doesn't support the J-Link natively)

When I compiled the SCSI2SD (not the USB_Bootloader project) the compiler wanted the USB_Bootloader.hex file for creating the SCSI2SD.hex file, so, I think that the compiler stuffs everything in the SCSI2SD project.

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32 minutes ago, techknight said:

What I am more curious about is if the SCSI2SD source can be ported to more available and cheaper ARM processors instead of the Cypress. 

I was asking myself the same thing, the 5LP costs about an eye for a single piece, but this would imply software and PCB adapting

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I've made clones of the v4 hardware design.  Some advice if you want to go down this route:

 

1) I had to roll my own PCB layout: the 74F06 chips used as bus buffers are now obsolete, and I wasn't able to find a part with a matching footprint.  The 74F126 is signal compatible, but since it only has 4 elements per unit, you'll need at least 5 of them instead of the 3 '06s in the original design.  There aren't all that many open collector/open drain ICs able to sink ~48mA these days...

2) The best way to program the boards (IMHO) is grabbing yourself a Cypress CY8CKIT-059 dev board.  Snap off the USB connector side and *bam* you got yourself a $10 programmer compatible with the Cypress software.  Since you're not doing any debugging, just flashing a simple bootloader, this was perfectly adequate for my needs.

3) Hand soldering the 0.5mm pitch 5LP is a real PITA, if you haven't experienced the joy of working with anything that small.

 

All told, I probably spent about $35-40 per clone, and after figuring in all the time spent on the project I would likely have been better off just buying a bunch of v5 boards at $70 a pop :)  Oh well.

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12 minutes ago, saybur said:

I've made clones of the v4 hardware design.  Some advice if you want to go down this route:

 

1) I had to roll my own PCB layout: the 74F06 chips used as bus buffers are now obsolete, and I wasn't able to find a part with a matching footprint.  The 74F126 is signal compatible, but since it only has 4 elements per unit, you'll need at least 5 of them instead of the 3 '06s in the original design.  There aren't all that many open collector/open drain ICs able to sink ~48mA these days...

2) The best way to program the boards (IMHO) is grabbing yourself a Cypress CY8CKIT-059 dev board.  Snap off the USB connector side and *bam* you got yourself a $10 programmer compatible with the Cypress software.  Since you're not doing any debugging, just flashing a simple bootloader, this was perfectly adequate for my needs.

3) Hand soldering the 0.5mm pitch 5LP is a real PITA, if you haven't experienced the joy of working with anything that small.

 

All told, I probably spent about $35-40 per clone, and after figuring in all the time spent on the project I would likely have been better off just buying a bunch of v5 boards at $70 a pop :)  Oh well.

At the moment I gave up and stored the compiled source everything in my HDDs, cloning this board is too expensive, especially for the 5LP and the 110 ohm resistors that costs an eye here in Italy.

When I'll want to burn money I'll clone it, at the moment I want to build DA15-VGA adaptors for my Macs.

 

Oh, a week ago I tried for the second time RaSCSI on my Pi Zero W, It's usable, but on 030 Macs doesn't works (I don't know why) and on 040 Macs sometimes it disappears, I used it well on my 6500/270, I also booted 7.6.1 from it, so, I think I'll build a RaSCSI cable.

Edited by MrGasS27

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Yeah, the 110ohm resistors are definitely getting harder to find.  SCSI allows an alternate configuration using 100ohm packs and dropping the terminator voltage to ~2.63V or thereabouts, if you want to try that in the future.

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5 minutes ago, saybur said:

Yeah, the 110ohm resistors are definitely getting harder to find.  SCSI allows an alternate configuration using 100ohm packs and dropping the terminator voltage to ~2.63V or thereabouts, if you want to try that in the future.

I know, my SCSI2SD v5 board has 100ohm resistor packs.

However, I'll hope that they'll release the v5 board's sources in future (It's an improbable thing, but dreaming is costless)

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There was a arduino sketch for programming the original SCSI2SD design, I don't know if the current boards use the same microcontroller but it might be worth a look at if you can find it (It was linked to in the original SCSI2SD thread years ago)

 

You can also use 150ohm resistors for termination, not strictly in spec but they work and 150ohm packs are allot easier to find. I used to use them on my SCA adapters and they worked just fine (although I did switch to just using single resistors in the end and ordered a reel of 110ohm resistors from china)

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8 hours ago, max1zzz said:

There was a arduino sketch for programming the original SCSI2SD design, I don't know if the current boards use the same microcontroller but it might be worth a look at if you can find it (It was linked to in the original SCSI2SD thread years ago)

 

You can also use 150ohm resistors for termination, not strictly in spec but they work and 150ohm packs are allot easier to find. I used to use them on my SCA adapters and they worked just fine (although I did switch to just using single resistors in the end and ordered a reel of 110ohm resistors from china)

Using an Arduino as SCSI device would be a beautiful thing, however, SCSI2SD has a Cortex M3 based microcontroller, the only Arduino with M3 is the "Due" model.

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Sorry i might have worded that badly, The arduino wasn't running the scsi interface - it was purely used to program the cypress microcontroller on the scsi2sd board, I only mentioned it as it ias a cheap alternative to the proper programmers for those chips

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