SDRAM Controller
3-66 ADSP-21368 SHARC Processor Hardware Reference
However, if an access to another bank occurs, the SDC closes the current
page open and issues another bank activate command before executing the
read or write command to that bank. With this method, called single bank
operation, Only one page can be open at a time.
Multibank Activation (ADSP-2137x Processors)
Unlike this command for the ADSP-21367/8/9 processors, if any other
access to another bank occurs, the SDC leaves the current page open and
issues a bank activate command before executing the read or write com-
mand to that bank. With this method, called multibank operation, one
page per bank can be open at a time, which results in a maximum of four
pages. For more information, see “Multibank Operation (ADSP-2137x
Processors)” on page 3-60.
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Multibank activation is only supported for the external banks 0
and 1.
Single Precharge (ADSP-2137x Processors)
For a page miss during reads or writes in any specific internal SDRAM
bank, the SDC uses the single precharge command to close that bank. All
other internal banks are untouched.
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This command is only supported for the external banks 0 and 1.
Precharge All
The precharge all command is given to precharge all internal banks at the
same time before executing an auto-refresh. All open banks are automati-
cally closed. This is possible since the SDC uses a separate SDA10 pin
which is asserted high during this command. This command proceeds the
auto-refresh command. Also, for single bank operation, this command is
used to close any open bank after a page miss detection.
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