MMC card interface

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MartinB
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Re: MMC card interface

Postby MartinB » Sun Mar 06, 2016 8:29 am

I was giving Jon something to do with his new DMM... :wink:

In fact Jon, because of voltage measurement settling times, it's probably better to either double the delay in line 60 from 100 to 200...

Code: Select all

60  T%=TIME:REPEAT UNTIL T%=TIME-200

...to give a two(ish) second +5v/0V toggle period or, even better, to show off your shiny new Digitek, shorten the delay in line 60 from 100 to 10...

Code: Select all

60  T%=TIME:REPEAT UNTIL T%=TIME-10

...and set the meter to frequency measurement (Hz) when you should measure approximately 5.0Hz on each PBn line :D

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sydney
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Re: MMC card interface

Postby sydney » Sun Mar 06, 2016 9:05 am

We built a couple of these at ABug in November and to avoid all the mess at the IDC connector we just used a standard user port cable and used a small piece of stripboard with some header pins to connect to the cable. We then simply soldered (or maybe we used headers sockets(?))the sd card pcb to the stripboard and used wires to connect the relevant pins. Maybe jbnbeeb or sPhilMainwaring could post some pictures.

JonC
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Re: MMC card interface

Postby JonC » Sun Mar 06, 2016 12:42 pm

MartinB wrote:I was giving Jon something to do with his new DMM... :wink:

Haha, I certainly need the practice!

sydney wrote:We built a couple of these at ABug in November and to avoid all the mess at the IDC connector we just used a standard user port cable and used a small piece of stripboard with some header pins to connect to the cable. We then simply soldered (or maybe we used headers sockets(?))the sd card pcb to the stripboard and used wires to connect the relevant pins. Maybe jbnbeeb or sPhilMainwaring could post some pictures.


This is the direction I'm heading at the moment, I have all the bits except the 20pin IDC header which I'm off to look for now. :)
I vaguely remember you building one that weekend, =D> :lol: .
Jon
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sydney
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Re: MMC card interface

Postby sydney » Sun Mar 06, 2016 7:49 pm

1st one took about an hour, second one took about 20 minutes :lol: !
We made lots of mistakes 1st time but second time I used the 1st one as a reference.

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CMcDougall
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Re: MMC card interface

Postby CMcDougall » Wed Apr 06, 2016 7:31 pm

JonC wrote:Ok, after much head scratching I'm on the verge of giving up

did you figure it out Jon?
I've just made another 3 from the 40p ones, and they now all work.......

...as noticed nothing wrong with my wiring, but the 40p boards must have different /crapper :x SD card holders on them :shock:
this was discovered by having a known working cable, board & 'micro SD to SD Adapter', then swapping over the board, then it did not work :shock:
so was about to write the boards off, but all I done was change the micro SD card adapter to a different make, & they all work :P
I had SanDisk, Toshiba, unbranded & Transcend adaptors, different combinations of these make them work, with same micro SD card inserted :D

so, if using just a SD card (without micro SD adaptors), maybe the holders can't make good sound contact with it :-k

\:D/ \:D/ \:D/
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JonC
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Re: MMC card interface

Postby JonC » Wed Apr 06, 2016 7:47 pm

CMcDougall wrote:
JonC wrote:Ok, after much head scratching I'm on the verge of giving up

did you figure it out Jon?
I've just made another 3 from the 40p ones, and they now all work.......

...as noticed nothing wrong with my wiring, but the 40p boards must have different /crapper :x SD card holders on them :shock:
this was discovered by having a known working cable, board & 'micro SD to SD Adapter', then swapping over the board, then it did not work :shock:
so was about to write the boards off, but all I done was change the micro SD card adapter to a different make, & they all work :P
I had SanDisk, Toshiba, unbranded & Transcend adaptors, different combinations of these make them work, with same micro SD card inserted :D

so, if using just a SD card (without micro SD adaptors), maybe the holders can't make good sound contact with it :-k

\:D/ \:D/ \:D/


I've given it a break for the moment, though I suspect the cheapo sd card holders are the culprit. :roll: [-X
I'll come back to it later. :mrgreen:
Jon
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sydney
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Re: MMC card interface

Postby sydney » Wed Apr 06, 2016 8:09 pm

Bring the bits to wakefield and I'm sure we'll get one working.

waltermixxx
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Re: MMC card interface

Postby waltermixxx » Sun Apr 24, 2016 2:43 am

Hi there, well it's that time again to build an MMC card interface...
this time i have a few of these Parallax Micro SD Card Adapters ( 32312 ).
schematic attached... Interesting thing about this device is, it appears all connections (except gnd and +3.3 volts, are being pulled up with 10K resisters. Please see page 4. :)

Just wondering, would I need to remove all the pull up resisters if I want to build the MMC interface based on this schematic:

circuit-e.jpg


or should I leave the 10k pull up resisters in place, and build the circuit as is, connected to the pins of this parallax device.
the resisters are on the bottom of the board so it will be difficult to remove them after the fact, if they interfere.

:) any assistance would be great. :)
Attachments
32312.pdf
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duikkie
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Re: MMC card interface

Postby duikkie » Sun Apr 24, 2016 4:13 am

put on your not seeing 10k glasses on :) , build if there are not there, it is useless for the userport because it can handle 5 volt as input , the card can only handle 3.3 volt . so the 5 volt from the beeb can harm your sd card.

so the 5 volt signals from the userport must be converted to 3.3 volt .

waltermixxx wrote:Hi there, well it's that time again to build an MMC card interface...
this time i have a few of these Parallax Micro SD Card Adapters ( 32312 ).
schematic attached... Interesting thing about this device is, it appears all connections (except gnd and +3.3 volts, are being pulled up with 10K resisters. Please see page 4. :)

Just wondering, would I need to remove all the pull up resisters if I want to build the MMC interface based on this schematic:

circuit-e.jpg


or should I leave the 10k pull up resisters in place, and build the circuit as is, connected to the pins of this parallax device.
the resisters are on the bottom of the board so it will be difficult to remove them after the fact, if they interfere.

:) any assistance would be great. :)

waltermixxx
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Re: MMC card interface

Postby waltermixxx » Sun Apr 24, 2016 4:57 am

Hi Duikkie, thanks for your reply but I am having trouble understanding it...
I know the BBC puts out 5 volt levels, and the SD card needs 3.3 levels. :) the schematic for the User port interface takes care of the level conversion, I was just wondering if I need to remove the pull up resisters on the parallax card or just leave them there.

Cheers. :)

duikkie
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Re: MMC card interface

Postby duikkie » Sun Apr 24, 2016 5:23 am

leave them. the 5 volt from the userport can harm your sd card because it can only handle 3.3 volt .
the 3.3 volt from the sd card can not harm the userport. therefore there are resistors to the sd card. there are other shematics to convert to 3.3 volt , but i am terrible in searching things

the idea is 10k---5k together 15k=5volt so over about 5k=3.3volt V=R*I and P=V*I .

[url]:)l]quote="waltermixxx"]Hi Duikkie, thanks for your reply but I am having trouble understanding it...
I know the BBC puts out 5 volt levels, and the SD card needs 3.3 levels. :) the schematic for the User port interface takes care of the level conversion, I was just wondering if I need to remove the pull up resisters on the parallax card or just leave them there.

Cheers. :)[/quote]

duikkie
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Re: MMC card interface

Postby duikkie » Sun Apr 24, 2016 5:58 am

i think all 10 k resistors have a main 3.3 volt line , cut that line and the resistors are not there anymore, maybe the input line have troubles with 3.3 volt (is a 1 , but i think it is always high if nothing is connected)

waltermixxx wrote:Hi Duikkie, thanks for your reply but I am having trouble understanding it...
I know the BBC puts out 5 volt levels, and the SD card needs 3.3 levels. :) the schematic for the User port interface takes care of the level conversion, I was just wondering if I need to remove the pull up resisters on the parallax card or just leave them there.

Cheers. :)

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DutchAcorn
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Re: MMC card interface

Postby DutchAcorn » Sun Apr 24, 2016 6:15 am

waltermixxx wrote:...this time i have a few of these Parallax Micro SD Card Adapters ( 32312 ).
schematic attached...

Out of curiosity; why not use one of these: http://m.ebay.co.uk/itm/Storage-Board-TF-Trans-flash-Card-Memory-Shield-Module-SPI-For-Arduino-GU-/351532338538

They are cheaper and include level conversion so can be connected directly to the user port.
Paul

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hoglet
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Re: MMC card interface

Postby hoglet » Sun Apr 24, 2016 6:42 am

I also would recommend an SD Card adapter with a level shifter chip.

But if you do roll your own, please be aware that I don't think the resistors on the schematic you posted are correctly connected as potential dividers for level shifting.

Dave

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CMcDougall
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Re: MMC card interface

Postby CMcDougall » Sun Apr 24, 2016 8:09 am

No need for them anyways, got 5x 40p China boards, still running at 5v and SD cards are still perfect....
The 99p board linked to above also works fine as got 2 of those also 8)
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fuzzel
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Re: MMC card interface

Postby fuzzel » Sun Apr 24, 2016 8:21 am

Apologies if I'm going over old ground here but this seems to be the perfect thread for my query.
I have an old BBC B and disc drive and plenty of old 5 1/4" discs and I'd like to get them copied over to my pc as ssd or dsd files.
What's the most straightforward way of doing this in terms of hardware and software? I don't mind spending a few quid on some hardware but I don't want to cannibalise my old beeb hardware and I'm useless with soldering irons.

duikkie
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Re: MMC card interface

Postby duikkie » Sun Apr 24, 2016 8:35 am

Open an other item you can use a mmc board.
fuzzel wrote:Apologies if I'm going over old ground here but this seems to be the perfect thread for my query.
I have an old BBC B and disc drive and plenty of old 5 1/4" discs and I'd like to get them copied over to my pc as ssd or dsd files.
What's the most straightforward way of doing this in terms of hardware and software? I don't mind spending a few quid on some hardware but I don't want to cannibalise my old beeb hardware and I'm useless with soldering irons.

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sydney
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Re: MMC card interface

Postby sydney » Sun Apr 24, 2016 9:00 am

fuzzel wrote:Apologies if I'm going over old ground here but this seems to be the perfect thread for my query.
I have an old BBC B and disc drive and plenty of old 5 1/4" discs and I'd like to get them copied over to my pc as ssd or dsd files.
What's the most straightforward way of doing this in terms of hardware and software? I don't mind spending a few quid on some hardware but I don't want to cannibalise my old beeb hardware and I'm useless with soldering irons.


UPURS is what you need. Use the forum search and you'll find it soon enough.

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CMcDougall
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Re: MMC card interface

Postby CMcDougall » Sun Apr 24, 2016 9:37 am

Or use the copy Disc >MMC program in the MMFS support thread, as can confirm works perfectly
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waltermixxx
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Re: MMC card interface

Postby waltermixxx » Sun Apr 24, 2016 11:43 am

I have a few of these eBay items already on order, slow boat from China. I happen to also have 4 of the Parallax devices already in my spare parts box, so I was hoping to utilize one in the mean time. I'm going to remove the 10k pull up resisters from the parallax device as the original Mmc schematic was designed to connect directly to an Mmc card.

Thanks folks for you input. :0). I'll report back when done.





DutchAcorn wrote:
waltermixxx wrote:...this time i have a few of these Parallax Micro SD Card Adapters ( 32312 ).
schematic attached...

Out of curiosity; why not use one of these: http://m.ebay.co.uk/itm/Storage-Board-TF-Trans-flash-Card-Memory-Shield-Module-SPI-For-Arduino-GU-/351532338538

They are cheaper and include level conversion so can be connected directly to the user port.

waltermixxx
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Re: MMC card interface

Postby waltermixxx » Sun Apr 24, 2016 10:35 pm

hoglet wrote:I also would recommend an SD Card adapter with a level shifter chip.

But if you do roll your own, please be aware that I don't think the resistors on the schematic you posted are correctly connected as potential dividers for level shifting.

Dave


the schematic posted is the original one from here:

http://swhs.home.xs4all.nl/bbc/mmbeeb/# ... cesoftware

The schematic from Parallax on page 4 of the PDF file attached to my post, does not use the resisters as voltage dividers, but just as pull ups, ( I removed them ).

The previous one i built (on page 14 of this thread worked great) but I leant it to a buddy who just acquired a BBC Model B. :)
so I was sharing the love to speak... (ok overboard...) at any rate I built the schematic as shown in the link and I am going to try it after dinner
and post pictures...

Wondering which line would be the best to add an "activity l.e.d." powered by a transistor, so I can get some "blink'n lights" with this :)

Cheers. :)

here is the unit completed, with just a power led. ( I want to add an activity led). :)

Image

Image

now i just have to desing a little 3d printed enclosure for it :)

Cheers. :)

waltermixxx
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Re: MMC card interface

Postby waltermixxx » Mon Apr 25, 2016 4:23 am

Printed the case for the BBC MMC. Thicker than before. Just need to print a lid for it. ( Tomorrow ). I left a small hole for an activity LED. He he.

Image

Image

derek
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Re: MMC card interface

Postby derek » Mon Apr 25, 2016 7:33 am

Hi,

What sort of 3D Printer did you use, I am looking to buy one in the future...
Regards,

Derek

duikkie
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Re: MMC card interface

Postby duikkie » Mon Apr 25, 2016 8:01 am

the beeb.mmb looks one of mine :P :D :shock:

waltermixxx
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Re: MMC card interface

Postby waltermixxx » Mon Apr 25, 2016 10:24 am

derek wrote:Hi,

What sort of 3D Printer did you use, I am looking to buy one in the future...


Makerbot Replicator 2 ( the previous generation ).

waltermixxx
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Re: MMC card interface

Postby waltermixxx » Wed Apr 27, 2016 12:44 pm

I'm going to tweek the design a bit of the case, so less of the board is exposed where the ribbon cable is attached. Also I'm wondering if Martin M might be able to chime in on something, As the creator of the device,
I'm wondering if and where I might connect an L.E.D. as an activity led?

I tried using an PNP transistor with 1.1K resister from the CB1 pin to the base, Emitter to +5volts, and then a 220 ohm resister to an L.E.D. to ground, although the interface still works, the L.E.D. remains on and does not appear to flash at all to indicate activity. I know the activity l.e.d. is not necessary, but it would be kinda cool to have. I'm wondering what might work better? I'm open to suggestions.

things i tried but also did not work:

CB2 did not work always on.
PB0 also did not work, always on.

LED-driver.gif


this sort of thing...

:) help?

duikkie
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Re: MMC card interface

Postby duikkie » Wed Apr 27, 2016 1:41 pm

maybe pnp broken ? goes the led off if base to high and on to gnd ? the low/high signal to fast for led and eye ?

waltermixxx
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Re: MMC card interface

Postby waltermixxx » Wed Apr 27, 2016 2:26 pm

The L.E.D. and transister seem to work,
if I put a high on the base through the resister, the l.e.d. goes off. when i switch it to ground, it goes Hi. so that works, when I connect it to any of the used pins on the User port, (PB0, PB1, CB1 or CB2) the led remains on, and does not fliker.... maybe it is just too fast? I'm thinking maybe trying a 555 instead? I love to build electronic things, but I'm better with 1, 0's than i am with transistors... :) and as much as I like to build, designing with transistors usually does not work out well for me. :)

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danielj
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Re: MMC card interface

Postby danielj » Wed Apr 27, 2016 2:40 pm

It's 115200 bps - I suspect anything over about 50-100 is going to be hard to see the flicker on :D

d.

waltermixxx
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Re: MMC card interface

Postby waltermixxx » Wed Apr 27, 2016 3:13 pm

I guess part of the issue is, at least according to my logic prope,
the line from PB1 goes high, (which should switch off the LED), then flashes off and on during activity.
but the LED seems to stay on, no matter what, technically, it should turn off, then flash (ok very quickly),
then go off again, as the line is held hi after sd card access... but no matter what the l.e.d. stays on...
I'm definitely missing something :)

Cheers. :)


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