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JESD84-A44% d6 C" p5 M8 \5 H0 S
DAT0-DAT7: These are bidirectional data channels. The DAT signals operate in push-pull mode. Only
) r2 x) B" w/ o& J( J$ `the card or the host is driving these signals at a time. By default, after power up or reset, only DAT0 is3 C( T; }! l) M
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.
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发表于 2015-5-18 16:51
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反对！
发表于 2015-5-26 11:41