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JESD84-A44
% }9 Y, W8 Q+ ^; |& hDAT0-DAT7: These are bidirectional data channels. The DAT signals operate in push-pull mode. Only' K+ p8 Q! C+ |' E+ T
the card or the host is driving these signals at a time. By default, after power up or reset, only DAT0 is
8 o4 X5 I, ~' o( B$ \$ z9 {JEDEC Standard No. 84-A44 Page 15 used for data transfer. A wider data bus can be configured for data transfer, using either DAT0-DAT3 or DAT0-DAT7, by the MultiMediaCard controller. The MultiMediaCard includes internal pull-ups for data lines DAT1-DAT7. Immediately after entering the 4-bit mode, the card disconnects the internal pull ups of lines DAT1, DAT2, and DAT3. Correspondingly, immediately after entering to the 8-bit mode the card disconnects the internal pull-ups of lines DAT1–DAT7.4 V/ o& v- {) \& w
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发表于 2015-5-18 16:51
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支持！
反对！
发表于 2015-5-26 11:41