Hi Expert,
客戶有使用MMC1 來接 MMC FLASH IC 取代一般 NAND 當開機與放程式使用,
同時又有使用GPMC 來接CPLD 轉接一般低速DEVICE.
然後我在技術文件(AM335X Technical Reference Menual) 中有看到一段MMC1描述:
是否說MMC1使用時 就不能再使用GPMC 介面嗎? 還是說只有共用PIN的地方不能使用?
(MMC1有佔到AD8~AD15)
26.1.7.5.2 System Interconnection Each interface has booting restrictions on which type of memory it supports: -
• MMC0 supports booting from the MMC/SD card cage and also supports booting from eMMC/eSD/managed NAND memory devices with less than 4GB capacity.
• MMC1 supports booting from eMMC/eSD/managed NAND memory device with 4GB capacity or greater. The restriction is a result of many eMMC devices not being compliant with the eMMC v4.41 specification. If you have the need to boot from two different card cages, many MMC/SD cards will boot from MMC1, but for maximum compatibility only MMC0 should be used to boot from the card cage. Similarly for maximum compatibility, booting from eMMC/eSD/managed NAND should only be performed on MMC1. Note that the above restrictions only apply to booting from each port. Drivers can be written for either port to support any desired interface. Note:
• The ROM Code does not handle the card detection feature on card cage.
• If MMC1 is used the GPMC interface is not usable, due to pin muxing options.
• MMC1 supports sector mode without querying the card
Thanks
Daniel
