====== SDHC Internal Buffer ======

{{template>meta:template:pageinfo#tpl
|desc=Introduce the internal buffer of SD host controller.}}

SD has an internal data buffer for data transfer. This buffer can only be accessed indirectly 
by the host driver through the ''32-bit'' <wrap reg>Buffer Data Port</wrap>. 

==== Buffer Size ====

=== Non UHS-II ===
The host controller shall have at least ''512'' bytes buffer. The size of the data buffer is 
determined by the setting of the <wrap reg>Block Size</wrap>.

=== UHS-II ===
The host controller shall have at least ''512'' * ''N_FCU'' bytes buffer. The size of the data buffer
is determined by the setting of the <wrap reg>Block Size</wrap> and ''N_FCU'' field in 
the <wrap reg>UHS-II Setting</wrap>.
<callout type="info">
''UHS-II Buffer Size'' = ''UHS-II Block Size'' * ''N_FCU''.
</callout>

==== Buffer Access ====