Atmel ATEVK525 Betriebsanweisung PDF herunterladen (Seite 11)

Using the ATEVK525

ATEVK525 Mass Storage Board for AVR 2-11

7740B–AVR–03/08

2.3 SD/MMC Card

The ATEVK525 includes a receptacle compatible with SD and MMC memory cards.

Figure 2-6 . SD card pinout (contact view)

Note: 1. The MMC card defined by specification v3.31 and earlier have only the pins #1 to #7

2. The MMC card defined by specification v4.0 and later (MMC Plus, Extra..) has 13

pins (increasing parallel data bus width)

Regardless of their differences, all SD/MMC cards have the following common points :

 SPI mode: through a standard SPI bus, that method reduces the transfert speed, but

is easy to implement. The alternate access method is a parallel mode

 Command set: cards have numerous commands that are common enough to

completely control the memory. Only the initialization process is different (but a

standard procedure automatically enables card identification and initialization). Be

aware of the card specification version (information contained in the CSD structure of

the card) before using advanced features (password protect, etc.).

Table 2-5 . SD/MMC card pin assignment in SPI mode

Pin # SD/MMC Card Function in SPI Mode AVR MCU

1 CS# Chip Select (active low) PORTB,0

2 DI SPI Master Out Slave In PORTB,2 (MOSI)

3 VSS Ground Gnd

4 VDD Supply Voltage Vcc

5 SCK SPI Clock PORTB,1 (SCK)

6 VSS Ground Gnd

7 DO SPI Master In Slave Out PORTB,3 (MISO)

1 2 ... 6 7 8 9 10 11 12 13 14 15 16 ... 29 30

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Atmel ATEVK525 Betriebsanweisung Seite 11