I.MX27 Datasheet(PDF) 11 Page - Freescale Semiconductor, Inc
FREESCALE [Freescale Semiconductor, Inc]
i.MX27 and i.MX27L Data Sheet, Rev. 1.5
Functional Description and Application Information
The ARM926EJ-S processor is a fully synthesizable macrocell, with a configurable memory system. Both
instruction and data caches will be 16 kbytes on the platform. The cache is virtually accessed and virtually
tagged. The data cached has physical tags as well. The MMU provides virtual memory facilities which are
required to support various platform operating systems such as Symbian OS, Windows CE, and Linux. The
MMU contains eight fully associative TLB entries for lockdown and 64 set associative entries. Refer to
the ARM926EJ-S Technical Reference Manual for more information.
Advanced Technology Attachment (ATA)
The Advanced Technology Attachment (ATA) host controller complies with the ATA/ATAPI-6
specification. The primary use of the ATA host controller is to interface with IDE hard disc drives and
Advanced Technology Attachment Packet Interface (ATAPI) optical disc drives. It interfaces with the ATA
device over a number of ATA signals.
This host controller supports interface protocols as specified in ATA/ATAPI-6 standard, as follows:
PIO mode 0, 1, 2, 3, and 4
Multiword DMA mode 0, 1, and 2
Ultra DMA modes 0, 1, 2, 3, and 4 with bus clock of 50 MHz or higher
Ultra DMA mode 5 with bus clock of 80 MHz or higher
Before accessing the ATA bus, the host must program the timing parameters to be used on the ATA bus.
The timing parameters control the timing on the ATA bus. Most timing parameters are programmable as a
number of clock cycles (1 to 255). Some are implied. All of the ATA device-internal registers are visible
to users, and they are defined as mirror registers in ATA host controller. As specified in ATA/ATAPI-6
standard, all the features/functions are implemented by reading/writing to the deviceâ€™s internal registers.
There are basically two protocols that can be active at the same time on the ATA bus, as follows:
The first and simplest protocol (PIO mode access) can be started at any time by the ARM926 to
the ATA bus. The PIO mode is a slow protocol, mainly intended to be used to program an ATA disc
drive, but also can be used to transfer data to/from the disc drive.
The second protocol is the DMA mode access. DMA mode is started by the ATA interface after
receiving a DMA request from the drive, and only if the ATA interface has been programmed to
accept the DMA request. In DMA mode, either multiword-DMA or ultra-DMA protocol is used
on the ATA bus. All transfers between FIFO and the host IP or DMA IP bus are zero wait states
transfer, so a high-speed transfer between FIFO and DMA/host bus is possible.
Digital Audio MUX (AUDMUX)
The Digital Audio MUX (AUDMUX) provides programmable interconnecting for voice, audio, and
synchronous data routing between host serial interfacesâ€”for example, SSI, SAP, and peripheral serial
interfacesâ€”such as, audio and voice codecs. The AUDMUX allows audio system connectivity to be
modified through programming, as opposed to altering the design of the system into which the chip is
designed. The design of the AUDMUX allows multiple simultaneous audio/voice/data flows between the
ports in point-to-point or point-to-multipoint configurations.
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