Intel PXA27 Series Design Manual page 261

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D.9 I C Bus Interface Unit
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The I C controllers in the PXA27x processor and PXA25x processor are similar with these
exceptions:
•
PXA27x processor contains a second I
IC.
•
For the PWR_I
— PWR_I
Kbps. When used with voltage change sequencer, PWR_I
When used outside of the voltage change sequencer, there are no restrictions to the use of
the I
— When the Voltage Change Sequencer is operating, (see Section 3.5.1.14 of the Intel
PXA27x Processor Family Developers Manual), the PWR_I
and reads unknown values. When Voltage Change Sequencer is operating, writing to
PCMDx and PVCR results in unpredictable operation.
•
When the PWR_I
— The sequencer only allows master-transmitter operations to a single, predefined slave.
— The sequencer does not send interrupts to the CPU, so interrupts other than "IDBR
Transmit Empty" are ignored and causes failure of the transmission.
— Fast mode of operation is not possible.
D.10 UARTs
The UART controllers in the PXA27x processor and the PXA25x processor are similar with these
exceptions:
•
The UARTs in the PXA27x processor is selected to use all 32 bits of the Peripheral Bus.
•
There is an option in the PXA27x processor that is enabled where the DMA removes any
trailing bytes in the receive FIFO. The PXA25x processor did not have this option and the
processor performed this task.
•
An autoflow mode has been added for the PXA27x processor.
•
Auto-baud functionality has been added for the PXA27x processor.
•
Registers FFFOR, BTFOR, and STFOR are new for FIFO occupancy information.
•
Registers FFABR, FFACR, BTABR, BTACR, STABR, and STACR are new to support auto-
baud functionality.
•
Registers RBR, THR, IIR, FCR, and MCR have new bits.
®
Intel PXA27x Processor Family Design Guide
®
Intel PXA27x Processor and Intel
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C controller only, these restrictions apply:
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C supports standard-mode operation of 40 Kbps and fast-mode operation of 100
2
C.
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C is used by the Voltage Change Sequencer, these restrictions apply:
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PXA25x Processor Differences
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C controller targeted for use with a power management
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C operates in standard-mode.
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C registers are not writable
D-7