I.MX27 Datasheet, PDF (19/148 Pages) Freescale Semiconductor, Inc – Multimedia Applications Processor

Functional Description and Application Information
schemes supported are fixed, programmable fixed, programmable default input port parking, and a round
robin arbitration scheme.
The Crossbar Switch also monitors the ccm_br input (clock control module bus request), which requests
a bus grant from all four slave ports. The priority of ccm_br is programmable and defaults to the highest
priority. Upon receiving bus grants for all four output ports, the ccm_bg output will assert. At this point,
the clock control and reset module (CRM) can turn off hclk and be assured there are no outstanding AHB
transactions in progress. Once the CRM is granted a port, no other master will receive a grant on that port
until the CRM bus request (ccm_br) negates.
2.3.23 Memory Stick Host Controller (MSHC)
The Memory Stick Host Controller (MSHC) is located between the AIPI and the Sony Memory Stick and
provides support for data transfers between the i.MX27 processor and the Memory Stick (MS). The MSHC
consists of two sub-modules; the MSHC gasket and the Sony Memory Stick Host Controller (SMSC). The
SMSC module, which is the actual memory stick host controller, is compatible with Sony Memory Stick
Ver 1.x and Memory Stick PRO. The gasket connects the AIPI IP bus to the SMSC interface to allow
communication and data transfers via the IP Bus.
NOTE
The i.MX27L does not include the MSHC feature.
The MSHC gasket uses a reduced IP Bus interface that supports the IP bus read/write transfers that include
a back-to-back read or write. DMA transfers also take place via the IP Bus interface.
A transfer can be initiated by the DMA or the host (through the AIPI) response to an MSHC DMA request
or interrupt. The SMSC has two DMA address modes—a single address mode and a dual address mode.
The MSHC is set to dual-address mode for transfers with the DMA. In dual-address mode, when the
MSHC requests a transfer with the DMA request (XDRQ), the DMA will initiate a transfer to the MSHC.
NOTE
Details regarding the operation of the MSHC module can be found
separately in Memory Stick/Memory Stick PRO Host Controller IP
Specification 1.3.
2.3.24 NAND Flash Controller (NFC)
NAND Flash Controller (NFC) interfaces standard NAND Flash devices to the i.MX27/MX27L
processors and hides the complexities of accessing the NAND Flash. It provides a glueless interface to
both 8-bit and 16-bit NAND Flash parts with page sizes of 512 Bytes or 2 Kbytes. Its addressing scheme
enables it to access flash devices of almost limitless capacity. The 2-Kbyte RAM buffer of the NAND
Flash is used as the boot RAM during a cold reset (if the i.MX27/MX27L device is configured for a boot
to be carried out from the NAND Flash device). After the boot procedure completes, the RAM is available
as buffer RAM. In addition, the NAND Flash controller provides an X16-bit and X32-bit interface to the
AHB bus on the chip side, and an X8/X16 interface to the NAND Flash device on the external side.
i.MX27 and i.MX27L Data Sheet, Rev. 1.5
Freescale Semiconductor
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