This page is for developers about logging to MMC
it takes complex and CPU-eating software to talk the MMC protocol (bidirectional data line, CRC ...). However most MMC cards support the SPI protocol, (which we also use for the knock-chip and MCP3208) so that is a logical choice. SD ... I don't know, but I'm sure it's no simpler than MMC. I hope most SD cards also support the SPI protocol.
TODO: describe these in a bit more detail:
Old thoughts:
For onboard logging (GenBoard/VerThree) we considered the SPI atmel flashes that appear MMC SPI-mode compatible:
- [ http://www.atmel.com/dyn/products/product_card.asp?family_id=616&family_name=DataFlash%AE&part_id=2471 At45DB161B 16Mbit]
- [At45DB321B 32Mbit]
- [At45DB642 is dual interface, big]
- [At45DB1282 is 128Mb version of the above.]
Real MMC is basically the same electrical interface and protocol, but more available and can be removed if a socket is used.
Some links
Working system with MMC and ATmega161:
- http://www.myplace.nu/mp3/ under hardware - yampp-7
Basic tech info about hw & sw interface system
Hitachi 16MB MMC-DataSheet as Sample
- http://www.squirrelpf.com/msavr/files/Hitachi16.pdf
- [SPI codee]
- [http://www.vems.hu/files/mmc/mmcsys-version_3-1.pdf
libraries:
- http://www.squirrelpf.com/msavr/files/mmc_eagle_lib_20040112.zip
- http://www.squirrelpf.com/msavr/files/MMCSocket20040111.zip
- http://www.squirrelpf.com/msavr/files/mmpack.zip
Tech sheets
- http://www.conwin.com.tw/multi.htm
- http://homepage.ntlworld.com/seanellis/mmcserial.htm
- http://www.singatron.com/MCC.asp
MMC and SD sources
Can someone check these Toshiba SD flash and comment on them? The question is if we can talk to it via SPI.
- SD-M3203B3
- SD-M6404B3 (1.5 *price of SD-M3203B3)
We would host in WebShop if suitable. Other type is OK, but we want to make sure to be fully compatible with our firmware and HW.
That aside, they are drivable through SPI (sure?)
Official doco appears to need licensed, but there's some limited info here - http://www.sandisk.com/oem/sd.asp
MMC sockets
also digikey has some sockets from HRC
hr845ct-nd $3.80
hr846ct-nd $3.80
Note that the MMC and SD have 7 pins with standard 2.54mm centerline so any card-edge connector should work. Your old 286 ISA motherboard comes to mind with a hammer in the background :-)
See also