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Architecture
1542
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Universal Parallel Port (uPP)
32.2.4.2 Data Interleave Mode
The data interleave mode is a special configuration that maps both DMA channels to a single interface
channel. Since there are only two DMA channels in the uPP peripheral, data interleave mode can only be
used when the uPP peripheral is operated in single-channel mode. There are two variants on data
interleave mode, each with special conditions:
•
Single Data Rate (SDR) Interleave – Transmit Only
–
UPCTL.CHN = 0 (single-channel mode)
–
UPCTL.DRA = 0 (single data rate)
–
UPCTL.MODE = 1 (transmit mode)
–
UPCTL.SDRTXIL = 1 (enable SDR transmit interleave)
–
UPCTL.DDRDEMUX = 0 (disable DDR interleave)
•
Double Data Rate (DDR) Interleave – Transmit or Receive
–
UPCTL.CHN = 0 (single-channel mode)
–
UPCTL.DRA = 1 (double data rate)
–
UPCTL.MODE = 0 or 1 (receive or transmit mode; not duplex)
–
UPCTL.SDRTXIL = 0 (disable SDR transmit interleave)
–
UPCTL.DDRDEMUX = 1 (enable DDR interleave)
describes the differences between single data rate (SDR) and double data rate (DDR).
In data interleave mode, only I/O Channel A is used. This single channel is associated with two data
buffers, each serviced by its own DMA channel (I and Q). In SDR interleave mode, the START signal is
used as a buffer selection line: START = 1 indicates that the current word comes from DMA Channel I;
START = 0 indicates that the current word comes from DMA Channel Q. In DDR Interleave mode, the
data buffers alternate every word beginning with Channel I: Channel I Word 0, Channel Q Word 0,
Channel I Word 1, Channel Q Word 1, etc.
shows signal diagrams for both data interleave
modes.
32.2.4.3 Interface and DMA Channel Mapping
Typically, DMA Channels I and Q are mapped to interface Channels A and B, respectively. Data interleave
mode is the exception, since it allocates both DMA channels to service interface Channel A.
summarizes DMA channel mapping for various modes of operation.
Table 32-4. Interface and DMA Channel Mapping for Various Operating Modes
I/O Channel Serviced
Operating Mode
DMA I
DMA Q
1-Channel Receive
A
—
1-Channel Transmit
A
—
2-Channel Receive
A
B
2-Channel Transmit
A
B
2-Channel Duplex
A
B
1-Channel Transmit (Interleave)
A
A
1-Channel Receive (Interleave)
A
A