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PXA300 Processor and PXA310 Processor
Vol. I: System and Timer Configuration Developers Manual
Doc. No. MV-TBD-00 Rev. A
CONFIDENTIAL
Copyright © 2006 Marvell
Page 100
Document Classification: Proprietary Information
December 13, 2006, Preliminary
Not approved by Document Control. For review only.
unpredictable order, non-obvious re-ordering of completion being possible. A completion can be checked only
by performing a read operation. Software should not assume that pins are programmed in exactly the order of
issue.
Each register is assumed to be 32 bits wide and with word-aligned access.
Each multi-function pin has a physical address in the overall processor-address map.
A single multi-function pin can have up to eight alternate functions and a low-power mode (during D1, D2, and
D3 states) value.
A multi-function pin always acts as an input (although the value may be ignored), which means that as long as
power is applied to the multi-function pin it must have a good logic value present on the board. This output can,
of course, be sourced from an external device or via the device driving itself.
A multi-function pin can be programmed to take one of five outputs values: resistive pullup (nominal 100K),
resistive pulldown (nominal 100K), driven high, driven low or high-impedance. Use three-state carefully to
ensure that no floating node remains on the board at any time. These states can be used to form multiple output
types (for example open collector, three-state drive etc.).
Note:
The mechanism differs considerably from previous versions of this function (for example, on the
Marvell PXA270 processor) where a control was provided to ignore the input of the pad (the
RDH control).
4.6.1
Checking for Completion of a Multi-Function Pin
Operation
A significant amount of queueing of operations is possible between software and the actual write of the
multi-function register. It is important that the software be programmed to detect when the last operation has
completed and taken effect. This detection is performed by a read operation to the address of the last operation
that was performed. No further pad-ring operation can be performed until that read response has returned (which
may be a significant amount of time). The returned data is meaningless and undefined.
4.6.2
Access to Nonexistent Registers or Pins
A write access to a register within the multi-function pin control region that does not exist is not aborted and
simply occurs with no effect. A read access to such a register proceeds in an identical manner to an access to an
existing register; however, the data returned is unpredictable.
4.6.3
Pin Control Unit Address Map
The address region for the multi-function pins is 0x40E1 0000–0x40E1 FFFF. Each location accessed is 32 bits
in size and is 32-bit-aligned in memory. Accesses to other sizes and alignments in this region are not permitted
and are undefined in effect.