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Colibri i.MX7 SD card interface

Disable SDIO​

The SD card interface can be disabled in Registry: Disable the SDCard driver.

Changing Card Detect Pin and Polarity​

The SD card detect pin and its polarity can be changed by adding the following values to the registry (<X> is the index of the SD controller you want to configure):


[HKEY_LOCAL_MACHINE\Drivers\BuiltIn\ESDHC]
"CardDetectPin" = dword:X   ; X = the SODIMM pin number of the CardDetect GPIO. 0xFFFFFFFF means no CardDetect pin ->fix inserted card.
"CardDetectPol" = dword:Y   ; Y = active polarity, 0: GPIO is low if card is available, 
                            ;                      1: pin is high if card is available.

Clock Speed and Misc Settings​

SD card clock frequency can be limited to a maximum value - this can be useful for debugging purposes to exclude hardware issues that may lead to bad signal quality at high frequency. The actual used frequency will be lower than MaximumClockFrequency.

ClockAlwaysOn has to be set to 0x1 if you want to prevent the clock being switched off if there is no communication going on. This is often used for SDIO WLAN adapters and similar devices.


[HKEY_LOCAL_MACHINE\Drivers\BuiltIn\ESDHC]
"MaximumClockFrequency" = dword:01298be0  ; Maximum SD card clock (Hz). Default 52MHz. 
"ClockAlwaysOn"         = dword:value     ; default value 0x0

Using WriteProtect GPIO​

Currently, the SDCard driver does not support WriteProtect feature.



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