MOTOROLA
MC68341 USER’S MANUAL
2- 13
The assertion level in external burst mode is level sensitive; in external cycle steal mode,
it is falling-edge sensitive.
2.8.2 DMA Acknowledge
(DACK2, DACK1)
DACK≈ is asserted by the DMA to signal to a peripheral that an operand is being
transferred in response to a previous transfer request. A delayed version of DACK≈ is
provided to allow operation with differing speed memories. The delayed form of DACK2
and DACK1 can be selected by setting bits 4 and 5 in the PPARC (See Section 6 DMA
Controller Module).
2.8.3 DMA Done (
DONE2, DONE1 )
This active-low output signal is asserted by the DMA or a peripheral device during any
DMA bus cycle to indicate that the last data transfer is being performed. DONE≈ is an
active input in any mode. As an output, it is only active in external request mode. An
external pullup resistor is required even during operation in the internal request mode.
2.8.4 Data Transfer Complete (
DTC)
This active-low bidirectional signal is asserted on all bus cycles (DMA and CPU initiated)
as an extra signal in standard bus timing. DTC is multiplexed with FC3, and is selected by
setting PPARC bit 3.
2.8.5 DMA Ready (
RDY2 , RDY1)
These active-low bidirectional signal is only asserted on DMA single-address transfers to
indicate that the device has supplied data or is ready to receive data from memory. RDY2
is multiplexed with TIN, and RDY1 is multiplexed with TGATE. RDY2 is selected by setting
PPARC bit 0, and RDY1 is selected by setting PPARC bit 1.
2.9 SERIAL MODULE SIGNALS
The following signals are used by the serial module for data and clock signals. See
Section 7 Serial Module for more information on these signals.
2.9.1 Serial Crystal Oscillator (X2, X1)
These pins furnish the connection to a crystal or external clock, which must be supplied
when using the baud rate generator. An external clock can be connected to the X1 pin; X2
is left floating in this case.
2.9.2 Serial External Clock Input (SCLK)
This input can be used as the external clock input for channel A or channel B, bypassing
the baud rate generator.
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