User's Manual Part 1

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MC75 Hardware Interface Description

Strictly confidential / Draft

MC75_V00.190a Page 47 of 91 15.02.2005

3.11 SD Memory Card Interface

The SD card interface is compliant with the “SD Memory Card Specifications / Part 1

Physical Layer Specification, Version 1.01”.

The interface supports the following features:

• Data rates up to 3250 kByte/s.

• The read/write data rate depends on the clock rate.

• SD card insertion detection (at SD_D3-line) or via SD_DET line as option (CD switch in

SD card holder required)

• Write protect detection via SD_WP line is optional (WP switch in SD card holder required)

• Maximum capacity of SD cards compliant with the above SD Memory Card Specification

is 4 GByte.

The SD memory card interface can be powered from an external supply or via the VEXT line

of MC75. If connected to the VEXT line the SD memory card interface will be properly shut

down when the module enters the Power-down mode. If you prefer to connect the SD card

interface to an external power supply, take care that the interface is shut down when the

PWR_IND signal goes high. See also Section 7 and Figure 39.

Note: No guarantee can be given, nor any liability accepted, if loss of data is encountered

after removing the SD memory card during operation.

Table 8: SD card interface

Signal I/O Description Remark

SD_D0 I/O ---

SD_D1 I/O ---

SD_D2 I/O ---

SD_D3 I/O

4 bit data bus

Card detect at power on:

0 or open = Card removed

1 or 50k pullup = Card inserted

Note: This is no removal detection during card

operation!

SD_CMD O Command / Response

SD_CLK O Clock 25.4kHz …13MHz

Clock rise and fall time: max. 10ns

SD_WP I Write protect detection 0= unlocked

1= locked

(External pull-up resistor required)

SD_DET I Card detection

(optional)

0= card inserted

1= card removed

Power supply from external source or from

VEXT line

Required power supply: min. 2.7V, max. 3.6V.

Note: Good care should be taken when creating the PCB layout of the host application: The

traces of SD_CLK, SD_CMD, and SD_D(0..3) should be equal in length and as short

as possible.