SD card data storage questions

Use a soldered in serial access Flash (Farnell have 1535453 16Mbytes for £9) and dump the data to the PC via a serial port. Cheap and easy. The serial port dump will be a bit slow (about half an hour for 16Mbytes @ 115.2kb) but that should be OK for the use you describe.

Michael Kellett

CF cards may be easier to use? Just an IDE interface I think. Not exactly "compact" by today's standards, of course...

Tim

-- Deep Friar: a very philosophical monk. Website:

or MMC, IIRC the interface is easily PICable.

Is selling a SD compatible device without joining the SD Card association really something you can get fined for?

What about a USB client port, and allow the use of USB thumb drives.

Or, do ye have to forcibly join the USB association for that ...

"Technically", I think so. (practically? )

IANAL.

I think at the very least they copyright the SD logo and your use of it in advertising your product would constitute an infringement. (I wonder if you could advertise as "uses those little postage stamp size memory cards commonly found in digital cameras" and get around this :> )

I believe their (stated) goal is to ensure the "quality" of compliant products is maintained so the market's image of that technology isn't tarnished. (Of course, I suspect they also have financial motives).

They could also want to protect IP as there are lots of other compact portable media that they are competing with for market share.

Personally, I'd use an inboard serial/data flash and a USB slave interface. "Look like a mass storage device" so you could just plug yourself into a PC "as a thumb drive".

Or, implement a USB host interface and expect the "data store" to be a mass storage device plugged *into* your device. Depending on the size/complexity of the product, this also opens other possibilities (e.g., you could attach a USB wireless device and use telemetry to deliver the data to a remote PC/collection device)

Huh? Do you mean a *host* port? I.e., to allow a thumb drive to be plugged *into* the DATAC system? Or, do you want the device to LOOK LIKE a "thumb drive"?

"Resistance is futile"

Er, Whoops - yeah, host.

Keyboard failure! :>

I think the problem there is the number of product (MCU) offerings with host support. :< Though I think it a much "slicker" way of approaching the problem (i.e., it might be diffcult to carry the logger *to* the PC if it was implemented as a "client/slave").

(see

IIRC, using an SD card in SPI (single-bit serial MMC-like) mode does not require a license. Only the 4-bit interface does.

Many PICs come with SPI controllers. The Microchip website has C code for using an SD card as a USB bulk storage device - you can scarf the SD control/read/write code from that.

-- Silvar Beitel

Am 13.04.2010 11:41, schrieb Richard Rasker:

No, it doesn't. An SD card is an MMC card plus some kind of copy procection (you are not going to use this) plus an additional 4 bit mode (you most probably won't need it).

And every single SD or MMC card I've come across had an SPI mode (although this seems to be optional). So it is basically an SPI storage medium.

There are also Atmel Dataflash devices in MMC package:

ee

I agree. This is my recollection as well on the last product we had that considered the use of SD Cards. The SPI mode did not require licensing or registration with SanDisk (or whomever).

In our project, we ended up using CompactFlash, which was trivial to implement.

The physical size difference between an SD Card and a CF Card doesn't seem like it would matter for this application. However, an SD Card might be the better choice from a vibration perspective as SD holders usually have a retention mechanism that CF holders do not. You wouldn't want the memory card falling out (vibrating out) during operation of the heavy machinery.

Someone else mentioned an EEPROM / Serial Comm port solution. This approach would also be cheap and easy, and quick to code/program. I'm just wondering if there's an easy (easier) way to transport (collect) the serial stream from equipment out in the field. Obviously a laptop, or netbook..., but anything else? Seems like that would have been beat to death by now. (?)

-mpm

Il Tue, 13 Apr 2010 11:41:32 +0200, Richard Rasker ha scritto:

Take a look at this:

If you need a good FAT library:

On a sunny day (Tue, 13 Apr 2010 12:49:29 -0700 (PDT)) it happened mpm wrote in :

It is called ethernet - internet. Implement an ethernet port. And then you do not have to go there.

I'm picture-ing a backhoe out in the mud. Are you suggesting an Ethernet connection on the data acquisition device mounted in the backhoe? To me, that seems like a worse idea than the serial port.

It also just occured to me that I don't know how to spell "picture- ing" :)

-mpm

Use a wireless interface. Depending on bandwidth, could be something as "slow" as low end zigbee. You can also buy radio modems in the 400MHz band.

On a sunny day (Tue, 13 Apr 2010 18:46:55 -0700 (PDT)) it happened mpm wrote in :

Had to look that up: '? n. a mechanical excavator that draws toward itself a bucket attached to a hinged boom.' mm WiFi. You still need the ethernet port. Can be done for under 100$ if you are clever:

Dictionary, google 'online dictionary', that is hoe I found 'backhoe'.

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You might look at the design of the PICkit 2 which has a usb interface = and=20 can store plenty of data in serial flash.