UART/Autobaud Functional Description
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12.5.4 FIFO Polled Mode
In FIFO polled mode (FCR [0] = 0, relevant interrupts disabled via IER) the
status of the receiver and transmitter can be checked by polling the line status
register (LSR). This mode is an alternative to the FIFO interrupt mode of
operation where the status of the receiver and transmitter is automatically
known by means of interrupts sent to the host (MPU or DSP).
12.5.5 FIFO DMA Mode
12.5.5.1 DMA Signalling
There are four modes of DMA operation: DMA mode 0, DMA mode 1, DMA
mode 2, and DMA mode 3. They can be selected as follows.
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When SCR[0] = 0:
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Setting FCR[3] to 0 enables DMA mode 0.
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Setting FCR[3] to 1 enables DMA mode 1.
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When SCR[0] = 1, SCR[2:1] determine DMA mode 0 to 3 according to
SCR register description.
So, for instance:
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If no DMA operation is desired, set SCR[0] to 1 and SCR[2:1] to 00 (FCR[3]
is disregarded).
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If DMA mode 1 is desired, either set SCR[0] to 0 and FCR[3] to 1 or set
SCR[0] to 1 SCR[2:1] to 01 (FCR[3] is disregarded).
If the FIFOs are disabled (FCR [0] = 0), DMA occurs in single character trans-
fers. When DMA mode 0 has been programmed, the signals
associated with DMA operation are not active.