UM10562 Datasheet, PDF (436/942 Pages) NXP Semiconductors – LPC408x/407x User manual

NXP Semiconductors
UM10562
Chapter 16: LPC408x/407x SD card interface
POWER
SUPPLY
MULTIMEDIA
CARD
INTERFACE
MULTIMEDIA CARD BUS
CARD
CARD
CARD
MULTIMEDIA CARD STACK
Fig 62. Multimedia card system
Multimedia cards are grouped into three types according to their function:
• Read Only Memory (ROM) cards, containing pre-programmed data
• Read/Write (R/W) cards, used for mass storage
• Input/Output (I/O) cards, used for communication
The multimedia card system transfers commands and data using three signal lines:
• CLK: One bit is transferred on both command and data lines with each clock cycle.
The clock frequency varies between 0 MHz and 20 MHz (for a multimedia card) or
0 MHz and 25 MHz (for a secure digital memory card).
• CMD: Bidirectional command channel that initializes a card and transfers commands.
CMD has two operational modes:
– Open-drain for initialization
– Push-pull for command transfer
• DAT: Bidirectional data channel, operating in push-pull mode
16.6.3 SD card interface details
Figure 63 shows a simplified block diagram of the SD card interface.
UM10562
User manual
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 13 September 2012
© NXP B.V. 2012. All rights reserved.
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