I understand that the high speed 4 bit mode for SD cards is some sort of proprietary protocol that you have to pay money in order to use, and you can get in trouble for distributing the documentation. My question is, is it possible for Netduino to pay for it and implement the 4 bit high-speed mode without negative consequences? I would love to see it implemented even if it's somehow a closed sourced portion of the open source firmware.
The LPC family of chips seems to implement this mode in hardware to avoid this problem, but GHI (who makes the USBizi used in FEZ) do not open-source their firmware, which is annoying since I need to put in some native code.
SD card 4 bit mode
Started by Frank26080115, Dec 03 2010 05:21 AM
2 replies to this topic
#2
Chris Walker
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Posted 03 December 2010 - 05:52 AM
Hi Frank26080115,
It might be possible to implement 1-bit mode for MicroSD cards on the Netduino Plus (since all the required wires are connected) via bit-banging. 4-bit SPI requires an additional connection to the MCU and is perhaps best done in the microcontroller hardware itself.
Most low-end microcontrollers tend to use SD cards in SPI mode, and that seems to fit well with Netduino Plus (plus it offers consistency with Netduinos using SD card SPI adapter boards). And we'd really hate to make part of the Netduino closed-source...that's just not in the Netduino DNA.
Thank you very much for your interest, and welcome to the Netduino community!
Chris
#3
Frank26080115
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Posted 03 December 2010 - 07:11 AM
Ah ok, my application doesn't need that much performance but it would have been nice. It looks like the SAM9 series has built-in SD card hardware, but those chips are overkill with 300+ pins.
Right now Netduino has won the war between SAM7 vs LPC for me, but it'll be awesome if Netduino firmware was ported over to LPC though
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