sd卡-mmc卡-CPU說(shuō)明資料:sd卡-mmc卡-CPU說(shuō)明資料SD Memory Card (Secure Digital Memory Card) is a memory card that is specifically designed to eet the security, capacity, performance and environment requirements inherent in newly emerging
audio and video consumer electronic devices. The SD Memory Card will include a copyright protection
mechanism that complies with the security of the SDMI standard and will be faster and capable
for higher Memory capacity. The SD Memory Card security system uses mutual authentication and
a "new cipher algorithm" to protect from illegal usage of the card content. A none secured access to
the user‘s own content is also available. The physical form factor, pin assignment and data transfer
protocol are forward compatible with the MultiMediaCard with some additions.
The SD Memory Card communication is based on an advanced 9-pin interface (Clock, Command,
4xData and 3xPower lines) designed to operate in at maximum operating frequency of 25MHz of
and low voltage range. The communication protocol is defined as a part of this specification. The SD
Memory Card host interface supports regular MultiMediaCard operation as well. In other words,
MultiMediaCard forward compatibility was kept. Actually the main difference between SD Memory
Card and MultiMediaCard is the initialization process.The SD Memory Card Specifications were divided to several documents. The SD Memory Card ocumentation structure is given in Figure 1.