Simple Electon MMC Interface

[flaxcottage]

[davidb]

That looks very useful. I'm sure there are a few people with Electrons but no Plus 1 expansions who would be interested in getting one of those.

With four spare I/O pins, surely you could connect directly to the SD card, or is level shifting needed?

[Ramtop]

An improved and more polished design with a few added features I something I'd like to do, this one was really just designed as a way for me to learn about the Elk and it is pretty rough in all honesty. It has a couple of missing traces that I only noticed after the PCBs arrived

The SD card could be direct attached, the CPLD is an XC9536XL so the I/O is 3.3v. But this was really just a quick hack with the parts I had to hand, which happened to include a level-shifted MicroSD board.

[daveejhitchins]

Yes, indeedy, it does

Dave H

[myelin]

After acquiring my first Electron less than a month ago I set out to design a bit of hardware to bung in the back of it. Working on the old principle of walking before you run, I decided on a very simple one-socket sideways ROM card. At the weekend I got the board up and running and was pleased to be able to declare 'mission accomplished'!

Nice work! Great to see a new Electron CPLD project -- it's so rewarding to boot the machine and see everything come to life

Did you find a new source for the plug to connect your board to the Electron's expansion port? I bought a few old-stock ones from CJE/4D on eBay a couple of years back, but have never been able to find a modern model number for those.

[Ramtop]

I have to admit to doing a bit of a happy dance when the board fired up first time

Alas, no new source for connectors. I bought some cheap ones on Ebay that are intended for vertical through-hole mounting and just bent the pins inward and soldered the ends to the PCB pads. It looks ugly and probably won't stand up to more than a few tens of insertions, but for a test board it does ok. The sheer kludgery of it vaguely irritates me, though.

I've found a current 50-way socket with a right-angle through hole mounting that I'd like to use in future (CR22-50D-2.54DSA is the model) but it's out of stock everywhere and on a 16-week lead time. There's also the Sullins EBC25DREH which is sporadically available in small quantities from Digikey and may be usable as it has solder eyelets 1.57mm apart.

[smokey]

Is anyone going to build these to sell as i am interested in one for my electron

James

[1024MAK]

Is anyone going to build these to sell as i am interested in one for my electron

James

Do you mean the gadget from Ramtop?
His sales thread is here but currently he’s sold out. I don’t know if he plans to make any more.

Mark

[Ramtop]

Is anyone going to build these to sell as i am interested in one for my electron

You've missed the boat for the moment; I've built loads of these cards, but just sold the last one yesterday.

More cards will be coming, but they'll be of an improved design that isn't quite ready yet.

[DaveLecky]

Hi Folks,

I’m trying to source a plug connection for the printer port of the Plus 1 for this project.

I’ve looked online and in the forum but can’t find anything.

My cables keep popping of at the worst times.

Can anyone help please.

Dave

[daveejhitchins]

Hi Folks,

I’m trying to source a plug connection for the printer port of the Plus 1 for this project.

I’ve looked online and in the forum but can’t find anything.

My cables keep popping of at the worst times.

Can anyone help please.

Dave

Let me look, tomorrow, and I'll see what I have . . .

If you don't hear back from me please drop me a PM.

Dave H

[1024MAK]

I’m trying to source a plug connection for the printer port of the Plus 1 for this project.

I’ve looked online and in the forum but can’t find anything.

Hi Dave

They are widely available, but the trick is knowing the correct search terms. Do you just want the connector, or do you want it already connected to a length of grey ribbon cable?
Try 26-way IDC like this on eBay

Mark

[DaveLecky]

Hi Mark,

Found them thanks.

For some reason I presumed the printer port connector was a D-Type ...should have gone to Specsavers....

Thanks

Dave

[daveejhitchins]

Hi Folks,

I’m trying to source a plug connection for the printer port of the Plus 1 for this project.

I’ve looked online and in the forum but can’t find anything.

My cables keep popping of at the worst times.

Can anyone help please.

Dave

Sorry . . . I don't seem to have an Electron Printer Port connector yet . . .

Dave H

[DaveLecky]

Hi Dave

Now I know what to order, I’ve got one coming from eBay......thanks for looking.

Dave

[DaveLecky]

Finally completed this project, I decided to go for an internal design.....

Dave

[daveejhitchins]

Dave H

[roland]

Superb idea

[0xC0DE]

Very nice!

[mr-macrisc]

That’s very cool indeed

[pmul128]

Hi,
Just built this for my Electron+Plus1, works great! Took the 5V from pin 1 of the joystick port. Really excellent work. I did have some differences between SD cards, I have a 32Gb microSD (with adapter) working fine. An older 2Gb (also with adapter) gives me the error "Card format?". I tried the debug version, the output is in the image. Is there anything you would like me to try with this card?

[hoglet]

Is there anything you would like me to try with this card?

Card Format? can normally be fixed by complely reformatting the card.

The best formatter is the one from the SD Association:
https://www.sdcard.org/downloads/formatter/

Dave

[pmul128]

Is there anything you would like me to try with this card?

Card Format? can normally be fixed by complely reformatting the card.

The best formatter is the one from the SD Association:
https://www.sdcard.org/downloads/formatter/

Dave

Tnx! I will try it out.

[pmul128]

Downloaded the formatter, formatted the 2Gb Samsung MicroSD card with "Overwite format" selected (also tried with "Overwite format" and "CHS format size adjustment"), copied some SSDs to the card, still get "Card format?". The card properties look like this (Win10)

I have three cards that do not work in the Elk, 2x2Gb and 1x4Gb, all Samsung MicroSD cards. All of them work (without reformatting) on my BBC B+ using a TurboSPI card. It's no biggie as the 32Gb card I tried works fine (also Samsung MicroSD), but if you want me to check something with the non-working cards, I will be happy to do so.

[pmul128]

Here is my take on how to do this from the wiring side (might provide inspiration for someone else):

I used two 26-pin IDCs and some flat cable. I removed the connecting pins on the SD card reader and mounted them so that they are accessible from the bottom of the PCB. Mounted it on a piece of patchboard with a 26 pin connector, then wired the SD reader to the connector with short lengths of wire. The only thing letting me down is the 5V from the joystick port, I did not have a d-sub connector in my spares box, I will add this later, and attach the 5v wire to the patchboard such that it is not pulling on the solder joint. If I ever get into 3D-printing it would be simple enough to add a box.

[DaveLecky]

Hi there,

See.... viewtopic.php?p=163755#p163755

And... viewtopic.php?p=254503#p254503

For more info on power and alternative internal solution.

Stay safe

Dave

[pmul128]

Hi there,

See.... viewtopic.php?p=163755#p163755

And... viewtopic.php?p=254503#p254503

For more info on power and alternative internal solution.

Stay safe

Dave

Yes, I had checked those out, but I am (was) reluctant to mod my Plus1, however after a second reading I think Hoglet's original solution adding the 5V to a spare pin on the printer port is probably the best method.

[pmul128]

Just a short footnote to this on the topic of working/non-working SD cards, in case it is of use to others. I built (using the same model of SD card reader, also the same one used by Hoglet at the start of this thread) an MMC interface for my Master Compact, connecting to the joystick port, also works really well. There I have the same combination of working/non-working SD cards as with the Elk. These cards all work OK on my B+, which has a TurboMMC connected to the user port. It looks like the non-turbo interfaces are more sensitive to the card type/brand/speed/something. Can anyone else confirm this behaviour?

[hoglet]

Can anyone else confirm this behaviour?

Just catching up here...

Is the issue still a Card Format? error with certain cards.

This is more likely to be a software issue than a hardware issue.

Can you clarify exaclty what software version you in each case?

I'm happy to investigate further, if someone wants to post me a non-working card.

Dave

[pmul128]

I was using the most recent MMFS versions downloaded from Github a few weeks ago, I will check the exact version number(s) tomorrow, as I am away from my Acorn machines right now. Should have been more precise with my report, the actually issue is "Card Format?" on both machines, the same cards are involved each time. I can send you one of the non-working cards, no problem. PM me with the address to use please.