TX buffer
max
Zero byte
Programmable
threshold
8 spaces
Example: DMA disabled to
show the end of the
transfer
Time
DMA active periods;
this does not represent
the DMA signaling.
1 character transmitted
uart-028
TX buffer max
Zero byte
Programmable
threshold
Characters transmitted from
the UART
Example: DMA disabled to show the
end of the transfer and the TX buffer
emptying.
1 space
Time
DMA active periods; this
does not represent the
DMA signaling.
uart-029
Preliminary
Architecture
www.ti.com
shows an example with 8 spaces to show the buffer level crossing the space threshold.
Again, the Local Host DMA controller settings must correspond to that of the UART/IrDA/CIR module.
Figure 19-23. Transmit FIFO DMA Request Generation (8 Spaces)
The final example illustrates the setting of one space which uses the DMA for each transfer of one
character to the transmit buffer (see
).. The buffer is filled at a faster rate than the BAUD
rate transmits data to the TX pin. Eventually, the buffer is completely full and the DMA operations stop
transferring data to the transmit buffer. There are two occasions where the buffer holds the maximum
amount of data words, shortly after this, the DMA is disabled to illustrate the slower transmission of the
data words to the TX pin. Eventually, the buffer will be emptied at the rate specified by the BAUD Rate
Settings of the DLL and DLH registers. Again, the DMA settings should correspond to the system’s
Local Host DMA controller settings in order to ensure the correct operation of this logic.
Figure 19-24. Transmit FIFO DMA Request Generation (1 Space)
1704
UART/IrDA/CIR Module
SPRUGX9 – 15 April 2011
© 2011, Texas Instruments Incorporated
Содержание TMS320C6A816 Series
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