GenBoard/LoggerIntegration/MMC (2006-06-02 04:12:36)

This page is for developers about logging to MMC

it takes complex and CPU-eating software to talk the native MMC protocol (bidirectional data line, CRC ...).

Since we also use SPI for the knock-chip and MCP3208, it was an excellent choice to provide HW support SPI-based MMC on GenBoard/VerThree.


Old thoughts:

For onboard logging (GenBoard/VerThree) we considered the SPI atmel flashes that appear MMC SPI-mode compatible:

Real MMC is basically the same electrical interface and protocol, but more available and can be removed if a socket is used.


Links

Working system with MMC and ATmega161:

Flashfile C library for MMC/SD FAThttp://www.avrfreaks.net/index.php?module=FreaksTools&func=viewItem&item_type=tool&item_id=516

Procyon AVRlib with MMC, FAT, IP, graphic lcd support and lots more http://hubbard.engr.scu.edu/embedded/avr/avrlib/

Basic tech info about hw & sw interface system

Hitachi 16MB MMC-DataSheet as Sample

Detailed MMC spec: 130 pages]

libraries:

Tech sheets


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.

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 :-)


Steps to make it work in SPI mode

AVR side

PC app

Future options


See also