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IDMA Channels
7-28
MC68360 USER’S MANUAL
ue should be less than the SDMA arbitration ID so that the
SDMA channels have priority over the IDMA channels. User
must program this field to 7 when the QUICC is configured in
slave mode.
7.6.2.2 CHANNEL MODE REGISTER (CMR). Each IDMA channel contains a 16-bit CMR
that is reset to $0000. It is used to configure most of the IDMA options.
ECO — External Control Option
Dual Address Mode: this bit defines which device is connected to the control signals.
0 = The control signals (DREQx, DACKx, and DONEx) are associated with the desti-
nation (write) portion of the transfer.
1 = The control signals (DREQx, DACKx, and DONEx) are associated with the source
(read) portion of the transfer.
Single Address Mode: this bit defines the direction of the transfer.
0 = The device writes to memory, and the control signals (DREQx, DACKx, and DON-
Ex) are used by the device to provide data during the destination (write) portion of
the transfer.
1 = The device reads from memory, and the control signals (DREQx, DACKx, and
DONEx) are used by the device to write data during the source (read) portion of
the transfer.
NOTE
If REQG is programmed to be internal (REQG = 0X), DREQx is
ignored.
SRM — Synchronous Request Mode
This bit controls how external devices may use the DREQx pin for IDMA service. This bit
is only relevant for applications that use external request mode or use the external DONEx
pin to terminate the IDMA operation.
0 = Asynchronous request mode is selected. The DREQx and DONEx input signals
are internally synchronized to the IDMA clock before they are used by the IDMA.
1 = Synchronous request mode is selected. The DREQx and DONEx input signals are
used by the IDMA without first being internally synchronized. This results in faster
operation, but should only be used if setup and hold times can be met.
S/D — Single/Dual Address Transfer
0 = The IDMA channel runs standard dual address transfers. Each transfer requires at
least two bus cycles. Data packing is performed using the DHR.
1 = The IDMA channel runs single address transfers from a peripheral to memory or
from memory to a peripheral. The transfer requires one bus cycle. The DHR is not
used for these transfers because the data is transferred directly into the destination
location.
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9876543210
ECO
SRM
S/D
RCI
REQG
SAPI
DAPI
SSIZE
DSIZE
BT
RST
STR
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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