Which ARM Microcontrollers are embedded in current SD Cards? The Motorola 8051 tends to get mentioned in this connection, with occasional, vague references to ARM. So, which specific ARM technologies are used for this purpose, and what kind of embedded OS do they use? Linux has been mentioned in this connection; do ARM SD implementations use it? If so, which disto(s)?
For controller on SD cards, normally it would be an faster-8051 with some hardware support for SD requirement. One example: 摰 蝘 - 脣 鋆 蔭閫 捱 寞 > SD Card Controller > AU7310T
If ARM core is used, it could be an application of "Bridge chip" for flash memory, or SSD controller. One example is using ARM9 http://www.jmicron.com/PDF/brief/jmf667.pdf . I guessed a simple OS would be sufficient.
Of course there is SD card with Wifi product on the market. This would require an ARM core and a better embedded OS, such as Linux.
Thank you, JEREMY, for your extremely helpful reply; the JMicron reference was particularly interesting. I was wondering, though, given the explosive growth in shipments of Cortex -M based products, particularly in the last year or so, whether some of those had found their way into SD Cards? Has anyone got any news on that front? Any comment, Saint Alban?
Not sure I have been canonised, yet. And I read the process can only start at least 5 years after your death...
It depends on what you want to offer. For a dumb SD Card, you want lowest cost possible. You want USB, an LED just because it's always better with a blinking LED, and interfacing the memory. The speed you want to achieve on the USB will most likely dictate which MCU you can use. Most likely some DMA would be desired...
An ARM Cortex-M0+ MCU should be able to achieve all that nicely with headroom.
I don't believe the OS matters much and I also agree with Jeremy that any responsive RTOS should do the job.
On top of the interesting links from Jeremy, I can recommend an article HCC-Embedded CEO wrote: Using NAND Flash with ARM Cortex Microcontrollers - Embedded Software Store - 210
Thank you, Alban, for your, as usual, omniscient response. One mystery solved. I note with interest that, whilst you cite the Cortex -M0+ as a microcontroller candidate (what a fascinating little beastie that is!), Dave Hughes mentions the -M4. Heavy metal, or what? So, that's the hardware sorted, now to nail down the OS issue...
From the paragraph, it looks like Dave Hughes recommended an ARM Cortex-M4 for enhanced ECC made on the MCU.
The ARM Cortex-M4 has additional DSP instructions (not a "secondary DSP core"). Some ECC algorithm might benefit from these additional instructions. These additional instructions take die area, so production cost is higher. I don't think this matters for a single home-made one, but I think any cent/penny has a major impact to the bottom line when you churn millions of them.
Also, at the time of the article, I don't believe the ARM Cortex-M0+ existed.
Here is attached an old table showing which instructions are supported by which core.
That's quite some little sketch, Alban! It does show the capabilities of the -M4 in this context, and it's tempting to think of it as a bit of a steamroller. The thing is, though, that the SD wallnuts are getting bigger and tougher all the time. The latest, high-quality 128GB versions retail at up to £90-plus hereabouts; that's SSD territoty, and the cost of an -M4 chip can easily be absorbed in those numbers. And, if Dave Hughes and his people are using them, then there's obviously a market out there. Here's a terrifying thought; the theoretical maximum capacity for an SD Card is 2TB......
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