Compact option for beeb MMC

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tricky
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Compact option for beeb MMC

Post by tricky » Sun Apr 09, 2017 8:31 am

Please note, before trying anything listed on this page, please check everything yourself as I only do bits of electronics as a hobby.

I hope I haven't posted this before, I have been meaning to for quite a while.

I have now made up several batches of "MMC" boards for my beebs, they fit in the slot under the beeb or master and directly connect to the user port. As these are for the machines that I show, the discs don't change very often (only when I write a new game ;)).

I had a bunch of spares at the last ABUG Cambridge and sold them, then made some more for my next set of beebs and have since just made another batch. The newer ones have a 3D printed case (## to do, add .zip ##) to support the connector during insertion and removal, although the boards are not really designed to be inserted and removed as the micro SD cards are fairly easy to change on the newer "tilted" design.

Anyway, enough history, here is what I did to build them:

I started with the smallest "99p" card I could find with level shifters http://www.ebay.co.uk/itm/10PCS-Micro-S ... SwsTxXiKDa (were £14 when I bought them) (ignore the bent pins, they were from a failed experiment)
Image
and used the wiring from the "99p MMC thread" (or go to Martin's page, listed at the bottom).
WiringMini.png
I bent the pins straight up, removing the GND pin and bending the VCC pin (now I don't bend them fully up to leave the board in a raised position). I also removed all the unwanted connectors from the IDC, to reduce friction and not short pins out!
Image
Please ignore the horrible state of the pins on this first prototype, there were quite a few experiments.
After being happy with the alignment, I soldered the board and IDC together (again with more experiments).
mini3.jpg
I found that the best (only!) way to get this done in a sensible way was to flatten one half of each "V" shaped connector and leave the other slightly raised to give the pins something to rest against.
The wire goes from CB1 through the board to SCK.
mini4.jpg
Another refinement is to not have the wire from CS to GND, to do this I scrape a little of the blue coating off near the CS pin and solder the pin to the board, which is GND.
mini5.jpg
As you can see, with the pins where they are on the original batch, there is not much spare room between the board and the case bottom, so I trim the pins and insert them a little further now.
side_view.jpg
You will also notice the 3D printed "case" which has a tag on it which fits in the cable grip on the IDC, meaning that the pressure when inserting and removing the board is on the plastic of the connector, instead of the soldering on the pins.
top_view.jpg
You can see the micro SD just poking out of the end of the board, it is spring loaded, so fairly easy to remove and insert, although I rarely change them on my beebs.
As you can see, one of the levers which holds the IDC in place is now under the board and releasing it to remove the board is a little awkward.
On the extras from the latest batch, you can see how the pins are trapped where the ribbon cable would usually be and the tag from the "case" is trapped where the ribbon cable would normally double back.
LatestBatch.jpg
I have always used SmartSPI (attached as SMART_SPI_1613.zip) as a couple of my beebs have Solidisk sideways RAM and I didn't want PB0..PB2 changed while accessing the SD card, nor the card getting messages while selecting sideways RAMs. I have stuck with it due to some compatibility issues with MMFS and the SD cards I had in the beginning, but it looks like the MMFS "partitionless cards" compatibility is now fixed (viewtopic.php?f=3&t=10621&p=164899&hilit=mbr#p164467), so either should be fine and with MMFS still being developed and offering page at &E00 with sideways RAM, it is probably the better option going forward.

To keep everything together, I will try to find a link to the latest BEEB.MMB and add the menu that I have added which also does a *FX 200,3 if necessary as some games (mostly mine) leave the beeb in an unhappy state! This looks good viewtopic.php?f=2&t=12641&hilit=beeb.mmb.

If you looking to buy one, this looks more robust viewtopic.php?f=3&t=12591&p=161236&hili ... 12#p161257.

Here is also a good summary post for DIY "MMC" SD card interfaces. viewtopic.php?f=3&t=12336&p=157125&hilit=99p#p157115

I think it is also important to thank Martin Mather, who I believe originally came up with the idea of connecting an SPI memory card to the beeb and is the MM in MMC. https://swhs.home.xs4all.nl/bbc/mmbeeb/ Also a good place to get the software for manipulating the beeb.mmb disc archive.

I will fill in the (##...##) as soon as I get a chance, but want to post this before I loose it (again!).
Attachments
SMART_SPI_1613.zip
Version I currently use
(11.38 KiB) Downloaded 35 times
mini2.jpg
mini2.jpg (34.93 KiB) Viewed 810 times
mini1.jpg
mini1.jpg (35.57 KiB) Viewed 810 times
Last edited by tricky on Sun Apr 09, 2017 1:11 pm, edited 8 times in total.

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tricky
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Re: compact option for beeb MMC

Post by tricky » Sun Apr 09, 2017 8:47 am

I seem to have hit an attachment limit.
Attached is the little menu (MENU.zip) I use with the check for 16K and reboot if it is, just hold shift down until the menu appears.
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Re: Compact option for beeb MMC

Post by flaxcottage » Sun Apr 09, 2017 9:53 am

This looks brilliant, thanks. :D =D> =D>

I have one of these cards so no excuse now! :lol:
- John
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tricky
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Re: Compact option for beeb MMC

Post by tricky » Sun Apr 09, 2017 10:11 am

I made them like this as I wanted them to be as small as possible, not to have wires floating around for shows and I don't need to change the cards very often. For a more home friendly version, I would consider mounting the card in an easily accessible place and using a less fiddly construction method. If it is just to make a beeb more useable, then they are OK.

EDIT: The wire going from CB1 to SCK is probably best not fitted through the hole!

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Re: Compact option for beeb MMC

Post by DutchAcorn » Sun Apr 09, 2017 12:07 pm

Looks like a nice and compact option, thanks for sharing!
Paul

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Re: Compact option for beeb MMC

Post by Andy1979 » Mon Apr 10, 2017 11:28 am

Thanks for the helpful guide - looks very neat. Great to have all the relevant forum threads in one place too.

Just ordered one of these little boards. When the slow boat from China arrives my plan is to attach it directly to a DB9 connector for the joystick/user port on my Master Compact. Hoping that it will fit inside something like this:
Image
Or failing that, this:
Image

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Re: Compact option for beeb MMC

Post by duikkie » Fri Apr 14, 2017 1:38 pm

i have made 4 by now it cost one hour to make :(
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Re: Compact option for beeb MMC

Post by duikkie » Fri Apr 14, 2017 1:45 pm

you don't need the yellow wire for cs ! around the cs there is all over gnd , with knife cut little bleu away from dot cs and you have gnd
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tricky
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Re: Compact option for beeb MMC

Post by tricky » Fri Apr 14, 2017 1:59 pm

Very nice, your also quicker at building them than me.
I did mention removing the CS wire between the two pictures with the yellow loop shown.

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Re: Compact option for beeb MMC

Post by duikkie » Fri Apr 14, 2017 2:18 pm

the most trouble is i use wire with plastic and they melt away

i must find a resin to put all over the socket an board make it firm
tricky wrote:Very nice, your also quicker at building them than me.
I did mention removing the CS wire between the two pictures with the yellow loop shown.

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Re: Compact option for beeb MMC

Post by duikkie » Thu Apr 20, 2017 2:51 pm

allmost big production in china speed :)
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Re: Compact option for beeb MMC

Post by tricky » Thu Apr 20, 2017 5:05 pm

And you can access the clamps to release them, but I doubt that they will fit a Master (I haven't checked ;))

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Re: Compact option for beeb MMC

Post by tricky » Sat Jul 07, 2018 2:25 pm

I finally got around to designing and ordering a batch of PCBs to make some more robust MMCs for my beebs.
I had a few of the older 5v boards without level shifters for the card, but as these are what all of my "show" beebs have and have never failed me, I took advantage of the special offer for 10 boards.
long_board.jpg
The idea was that I could have the cards just poking out from under the front of the machine for easy access for my test machines (when they aren't packed away) but still added a backup set of holes in case I changed my mind.
I also made a smaller board with options to choose the orientation of the SD card reader to allow for the different clearances of the different machines.
short_master.jpg
In the master, the board can face the 1MHz bus making use of the plastic separator sticking out to give more room.
My original plan was to allow the card to just poke out from under a master in the same way as the longer board does on a beeb, but I put the holes in the wrong place. I have also labelled the holes parallel to the connector back to front, but the other two sets are labelled correctly.
short_board.jpg
The short boards can be used in any of the three orientations, but are labelled to suggest that they point to wards the printer port where there is a gap on a model B or towards the 1MHz bus where there is a gap on the master. Either can point forwards and any orientation can be angled away from the beeb to give more room for not so delicate fingers :lol:

As I started fitting some to my beebs, I rediscovered that some of the plastic clips have their notches closer to the pins than others. I wasn't expecting this as I had assumed (making an ass out of me :oops:) that all connectors would be the same, but now I remember that they aren't. This doesn't stop them working, but if I wan't to make them look perfect (I don't) then I will have to trim them with a "dremmel".

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tricky
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Re: Compact option for beeb MMC

Post by tricky » Sun Jul 08, 2018 9:55 am

I made up a few more test boards:
test_boards.jpg
And this is the one that sticks out under the fron of a beeb, in use (balanced on top of another beeb).
board_in_use.jpg

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Re: Compact option for beeb MMC

Post by Elminster » Wed Aug 01, 2018 6:59 am

I missed this one from the hardware list, unless it is on by another name and you making one of the DIY designs. If not I will Added when I get a chance. This is an aide memoir.

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tricky
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Re: Compact option for beeb MMC

Post by tricky » Wed Aug 01, 2018 7:21 am

I hadn't made them to sell, nor my Atari to beeb joystick adapters and as they are "leaded" I wasn't sure I could.
I am happy to sell the odd one here and there as the excess helps save more Beeb's ;)
The joystick adapters can have a case and the beeb end can be attached with a cable if required.

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Elminster
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Re: Compact option for beeb MMC

Post by Elminster » Wed Aug 01, 2018 9:15 pm

Just a list of stuff be it design only, diy, built at cost or built to vast sums of money requiring selling of soul.

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Re: Compact option for beeb MMC

Post by Elminster » Fri Aug 10, 2018 10:27 am

For this one I will give it to categories 'prebuild' and 'design only' as could be either.

And attibute to You and 'et al.' as various flavours of software and hardware that could be used.

Link will point back to this entry anyway.

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