Intel PXA26X User Manual Page 597

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Intel® PXA26x Processor Family Developer’s Manual 17-13
Hardware UART
17.5.4 Interrupt Enable Register (IER)
The IER enables the five types of interrupts that set a value in the Interrupt Identification Register
(IIR). To disable an interrupt, software must clear the appropriate bit in the IER. Software can
enable some interrupts by setting the appropriate bit.
The Character Timeout Indication interrupt is separated from the received data available interrupt
to ensure that the processor and the DMA controller do not service the receive FIFO at the same
time. When a Character Timeout Indication interrupt occurs, the processor must handle the data in
the receive FIFO through programmed I/O.
Enabling DMA requests also enables a separate error interrupt. For additional information see
Section 17.4.2.5.
Bit 7 of the IER is used to enable DMA requests. The IER also contains the unit enable and NRZ
coding enable control bits. Bits 7 through 4 are used differently from the standard 16550A register
definition.
The IER bit definitions are shown in Table 17-6.
Note: MCR[OUT2] is a global interrupt enable, and must be set to enable UART interrupts.
Table 17-6.
IER Bit Definitions (Sheet 1 of 2)
Physical Address
0x4160_0004
Interrupt Enable Reg. (IER)
PXA26x Processor Family Hardware
UART
User
Settings
Bit 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reserved
DMAE
UUE
NRZE
RTOIE
MIE
RLSE
TIE
RAVIE
Reset ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 0 0 0 0 0 0 0 0
Bits Access Name Description
31:8 N/A Reserved – Read as unknown and must be written as zero.
7R/WDMAE
DMA REQUESTS ENABLE:
0 – DMA requests are disabled
1 – DMA requests are enabled
6R/WUUE
UART UNIT ENABLE:
0 – the unit is disabled
1 – the unit is enabled
5R/WNRZE
NRZ CODING ENABLE:
NRZ encoding/decoding is only used in UART mode, not in infrared mode.
If the slow infrared receiver or transmitter is enabled, NRZ coding is
disabled.
0 – NRZ coding disabled
1 – NRZ coding enabled
4R/WRTOIE
RECEIVER TIME OUT INTERRUPT ENABLE (Source IIR[TOD]):
0 – Receiver data Time out Interrupt disabled
1 – Receiver data Time out Interrupt enabled
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