BeebSCSI 7_7

[simoni]

BeebSCSI has a newly designed (KiCAD) PCB now available that is smaller and designed for both internal mounting (in the BBC Master) or mounting in an external case:

Github - https://github.com/simoninns/BeebSCSI
BeebSCSI documentation - https://www.domesday86.com/?page_id=689

The new design also allows for right-angled IDC and other headers to be used (in order to fit better in the Elk AP5 expansion as well as other mounting applications where a <12mm height is preferable).

I'll be making a 2_4 release on Github shortly (the board is firmware compatible with the 7_5 version and the 'unofficial' BeebSCSI 'mini' version, but here are the highlights of the new PCB design:

• Smaller PCB (66 x 51mm)
• Four M3 mounting holes (fits both Master AIV slot as well as external case mounting)
• Straight and right-angle configuration (all sockets and headers can now be right-angled if required)
• Single JTAG programming chain with shared header (between AVR and CPLD)
• Support for Tag-Connect programming adapters
• Fiducial markers for pick-and-place manufacturing compatibility
• All components on top-copper layer
• Improved silkscreen with better component orientation markers
• Design rebuilt using KiCAD rather than (closed-source) EagleCAD
• New microSD socket (provides overhang of the microSD card for better internal and case mounting options)
• All active and passive component SMT (except headers and connectors)
• JST-EH power connector to prevent incorrect cable orientation
• USB to AVR header with required USB support components (to support future expansion)
• All SMT passives now 0805 footprint

As before, the design (both hardware and software) is completely open-source and you are free to use, modify and build upon the design.

[ask_nz]

Ade

[simoni]

There is also a new version of the BeebSCSI firmware available now (V2.4):

https://github.com/simoninns/BeebSCSI/releases/tag/V2.4

This release adds enhancements to the debug output (to assist people making boards) as well as PWM brightness control of the status LED. Now, instead of flashing on and off, the LED glows with minimum brightness to show the board is powered and ready. On activity the LED shows full brightness and then fades off. Not much of a feature enhancement, but it sure looks nice

As usual you can simply grab the release files and use the BEEBSCSI.BIN to upgrade the firmware via the microSD card. This firmware version is compatible with all variants of BeebSCSI (7_5, 7_7 and the 'mini').

[danielj]

Aotta - the entire design is open:

https://github.com/simoninns/BeebSCSI

No one's making them at the moment - if you wanted to put a batch of 10 together, you'd probably be able to shift them all?

d.

[aotta]

i love solder and working over old pcbs, but this new one boards need solder point too little for my eyes... i can give a try for myself, but not intend to project a batch for reselling: i will probably burn more component than i will be able to place!

If someone else is interested, perhaps we can create a group for ordering togheter a batch of empty pcbs

[danielj]

Use jlcpcb.com, you can get 10 PCBs for $2+shipping!

d.

[simoni]

To remove any guesswork, I've included the manufacturing specs for the PCB on the project pages (these match JLCPCB's options):

https://www.domesday86.com/?page_id=409 ... nformation

There's a bill of materials on the page also.

For soldering the board together (with a normal soldering iron) I'd recommend you use an iron with around 65W power - use a 1.5mm tip for all the 0805 components and AVR and a 0.4mm tip for the CPLD. The smaller tip for the ICs lets you easily remove any solder bridges between the pins. I usually just run the solder along the pins, use 2mm desoldering braid to remove the excess and then check for and remove any remaining bridges with the small tip. As long as you use plenty of flux it's a pretty easy process.

The new 7_7 board is designed to make hand-construction much easier. It also has fiducials to allow pick and place assembly... so you could even get the board house to populate the boards for you.

[aotta]

Thank danielj and simoni, great hints, specially the site for ordering pcbs... For smallymouse pcb last time i spent about 30£! I will place orders for board and components today!

[danielj]

If you're in no rush, I've used airmail with jlc and it turns up in about 2 weeks in the UK

(I think the mosfet is the fiddliest of all the things on there!)

d.

[aotta]

If you're in no rush, I've used airmail with jlc and it turns up in about 2 weeks in the UK

(I think the mosfet is the fiddliest of all the things on there!)

d.

i can wait and just ordered the pcb from jlc... and adding components to my farnell basket but... considering the minimun quantity for each component, it's already over the 50 pounds plus p&p, and counting...
DIY one pieces only seem an expensive solution

[simoni]

DIY one pieces only seem an expensive solution

The BoM cost per board comes out at around 25 UKP a board depending on quantity (which isn't really that much ); whichever way you do it, making several requires some investment. Single quantities are more costly, as are distributors like Farnell. The most cost effective way is with patience (so you can order from further away) and quantity (10 at a time at least).

BeebSCSI isn't a turboMMC or IDE adapter... it's a highly capable SCSI-1 emulation and analysis device with a lot of capability (it was originally designed to help reverse-engineer Domesday). On the plus side it is exactly like using the original Winchester systems from Acorn, so it's compatibility is second-to-none. The whole design and source is also open; for other (less capable) solutions you have to pay more than twice as much; most of which is just profit - BeebSCSI itself is totally free

[aotta]

i use turboMMC with my compact, but i must admit that i am fallen in love reading about beebscsi project...
as said, just ordered the pcb, but closed farnell page (italian ones) when prompting me a checkout of over 70 euros with tax and postage...
i need save some money for restoring an A4000 (with battery leaked) i just bought, and adding an ide interface to my A3000 (but, there is a way to use beebSCSI with the A3000? maybe with a serial minipodule that adds the userport?) so, for the moment, i go in standby.
Maybe i will buy some components during next months, perhaps someone with more skill will make some new batch, we never know..
Anyway, my compliments for the incredible works in domesday86 project!

[simoni]

but, there is a way to use beebSCSI with the A3000?

Well, BeebSCSI is two things... An Acorn SCSI-1 host adapter (well, 3 things - since it's also an AIV SCSI adapter) and a SCSI-1 drive emulator. The SCSI-1 drive emulator is probably quite universal, but the host adapter isn't really suitable for anything other than a Beeb.

It's probably a lot simpler just to use an IDE drive; but, having said that, it's all open-source, so you are free to hack it to do anything you like. Personally I have no plans to support any of the 24/32 bit machines with it.

Anyway, my compliments for the incredible works in domesday86 project!

Thanks!

[alienkidmj12]

is someone selling these? any left ?

ignore me, i already have 7.5 rev

[Elminster]

If you're in no rush, I've used airmail with jlc and it turns up in about 2 weeks in the UK

(I think the mosfet is the fiddliest of all the things on there!)

d.

i can wait and just ordered the pcb from jlc... and adding components to my farnell basket but... considering the minimun quantity for each component, it's already over the 50 pounds plus p&p, and counting...
DIY one pieces only seem an expensive solution

How many boards did you order in the end, and what was your plan for any spares?

I was think of ordering some but if you have already ordered a batch and don’t need the others I could take one off your hands.

[aotta]

If you're in no rush, I've used airmail with jlc and it turns up in about 2 weeks in the UK

(I think the mosfet is the fiddliest of all the things on there!)

d.

i can wait and just ordered the pcb from jlc... and adding components to my farnell basket but... considering the minimun quantity for each component, it's already over the 50 pounds plus p&p, and counting...
DIY one pieces only seem an expensive solution

How many boards did you order in the end, and what was your plan for any spares?

I was think of ordering some but if you have already ordered a batch and don’t need the others I could take one off your hands.

Yes, i can send you one, i have 10 pcb but no component to fill in..
Pm me your detail

[Elminster]

Sounds like a start. PM Sent.

[Elminster]

I am assuming that people are building the beebscsi with a straight female connect for fitting under Beeb or to an AP5, or the right angled connectors when dangling from a cable?

[danielj]

Only the mini fits under the beeb (and only the beeb, not the master). Straight through hole male for cable dangling: https://www.domesday86.com/?page_id=409 ... _Materials

But the right angled can be used for the AP5.

[Elminster]

Only the mini fits under the beeb (and only the beeb, not the master). Straight through hole male for cable dangling: https://www.domesday86.com/?page_id=409 ... _Materials

But the right angled can be used for the AP5.

Yes I was looking at the BOM and wonder which to order.

But assume with the exception of fitting under the Beeb this is just personal preferencance.

[danielj]

Yes I was looking at the BOM and wonder which to order.

But assume with the exception of fitting under the Beeb this is just personal preferencance.

The straight will fit a standard cable better as the connector is at right angles to the cable. The right angle will plug directly into the AP5. You won't be able to plug this version under a beeb - only the version Jason made fits. Unless you're using it on the AP5 exclusively, get the straight. This is probably the wrong thread for this - I'll find the original beebscsi thread and move the posts.

[Elminster]

Think I am confused about what is at a right angle, the connector to the board, or the pins.

[simoni]

You can purchase either a straight IDC socket, or an angled IDC socket. If you use an angled IDC it fits flush to the board over the two rear mounting holes (pictured of both configurations are shown on the BeebSCSI hardware page). The 7_7 board is designed to be cased, so you can either:

Use a straight IDC and case/mount it using all four mounting holes.
Use an angled IDC and case/mount it using the front two mounting holes (as that is where the 'stress' from the SD card insertion will be)
Use an angled IDC socket with 'levers' and mount it using the front two mounting holes and the two holes in the levered IDC socket.

Option 3 is what (I believe) is being used for the AP5 - I added the angled IDC socket capability for David H just for this purpose.

The advantage of 'straight' connectors is that the board is narrow and fits down the side of a Master's PCB (in the AIV SCSI slot). The advantage of angled is the board height is very low, meaning you can put it in a very low profile case.

The straight connectors (with 4 mounting holes) are also useful for mounting internally (in a Beeb) as you can use 4 self-adhesive stand-offs to hold the board in place.

The 7_7 board doesn't mount under the Beeb though (unlike Jason's 'mini' design) - as that design is only really useful for mounting under a Beeb since it's difficult to mount it elsewhere. The 7_7 board is long enough that it matches with the AIV SCSI board mounting holes inside the Master; any shorter and this isn't possible - which is why it doesn't fit under the Beeb.

[Elminster]

As I thought was talking cross purposes. I had meant cable fitted at angle (straight idc pin connection) or connector flush ‘straight out from board’ (Angled idc connector).

Not an issue whether fits underneath as I plan inside a master (need to sort the other board at some point) and on an AP5.

Was just getting confused by ambiguity. So I need one ‘straight’ for master and one ‘angled’ for Electron.

[simoni]

There's really only one type of cable connector; so it's just the type of socket on the BeebSCSI that can be varied. Sounds like you have a plan now though

[Elminster]

There's really only one type of cable connector; so it's just the type of socket on the BeebSCSI that can be varied. Sounds like you have a plan now though

Yep thanks. Just wanted to check I ordered the right bits for the right job and didn’t fit the wrong bits and then try to fit a round peg in a square hole.

Thanks all.

[1024MAK]

There's really only one type of cable connector; so it's just the type of socket on the BeebSCSI that can be varied. Sounds like you have a plan now though

Just to add to the confusion, the normal description in the U.K., is that for the normal dual pin IDC connectors, the PCB mounting part is the male plug. The connector that fits the male plugs, that attach to ribbon cable are line sockets.

Mark

[cmorley]

Just to add to the confusion, the normal description in the U.K., is that for the normal dual pin IDC connectors, the PCB mounting part is the male plug. The connector that fits the male plugs, that attach to ribbon cable are line sockets.

I am not sure that is right...
Isn't a PCB box header a receptacle with pins and the cable end a plug with sockets?

Pins and sockets describe the individual connection's terminals. Plugs and receptacles describe the connector as a whole. You can have plugs with pins or sockets and receptacles with sockets or pins... all the combinations.

[Elminster]

Next you will be telling me not to use supergkue

[danielj]

Don't use superglue. Top tip.