CLOCK(i)
START(i)
ENABLE(i)
WAIT(o)
DATA(i)
D1
D2
D3
D4
D5
Architecture
1544
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Universal Parallel Port (uPP)
When the channel is configured in transmit mode with data interleave enabled (SDRTXIL = 1 in UPCTL),
the START signal function changes completely. The START signal now asserts on every data word that is
provided by DMA Channel I. See
for this alternative behavior.
32.2.5.4 ENABLE Signal
The uPP transmitter asserts the ENABLE signal when it transfers a valid data word. The ENABLE signal is
active-high by default, but its polarity is controlled by the ENAPOLx bit in UPICR.
In transmit mode, ENABLE is an output signal and is always driven; in receive mode, ENABLE is an input
signal and may be disabled using the ENAx bit in UPICR.
32.2.5.5 WAIT Signal
The WAIT signal allows the receiver to request a temporary halt in data transmission. When the receiver
asserts WAIT, the transmitter responds by stopping transmission (starting with the next word) until WAIT
is released. The receiver ignores all incoming data until WAIT is released. Once WAIT is released, the
transmitter can resume transmission on the next word.
shows WAIT signal timing. The WAIT
signal is active-high by default, but its polarity is controlled by the WAITPOLx bit in UPICR.
In transmit mode, WAIT is an input signal and may be disabled using the WAITx bit in UPICR; in receive
mode, WAIT is an output signal.
32.2.5.6 CLOCK Signal
The uPP transmitter drives the CLOCK signal to align all other uPP signals. By default, other signals align
on the rising edge of CLOCK, but its polarity is controlled by the CLKINVx bit in UPICR. The active
edge(s) of CLOCK should always slightly precede transitions of other uPP signals.
In transmit mode, CLOCK is an output signal; in receive mode, CLOCK is an input signal. See
for more information on clock generation and allowed frequencies.
32.2.5.7 Signal Timing Diagrams
In the following diagrams, signals are marked (I) to indicate that they are inputs to the uPP peripheral and
(o) to indicate that they are outputs from the uPP peripheral. Data words from a single DMA channel are
designated Dx, while data words that must come from a specific DMA channel are designated Ix or Qx to
indicate DMA Channel I or Q, respectively. For more information on DMA channels and data interleave
mode, see
.
All signal diagrams are drawn with signal polarities in their default states. All signals except DATA are
independently configurable in the uPP interface configuration register (UPICR).
Figure 32-9. Signal Timing for uPP Channel in Receive Mode with Single Data Rate