Motorola PowerQUICC II MPC8280 Series Reference Manual page 704

IDMA Commands
Table 19-10. IDMA BD Field Descriptions (continued)
Offset Bits Name
6 SDTB
7-15 —
0x04 0–31 Data Length Number of bytes the IDMA transfers. Should be programmed to a value greater than
0x08 0–31 Source
Buffer
Pointer
0x0C 0–31 Destination
Buffer
Pointer
19.9 IDMA Commands
The user has two commands to control each IDMA channel. These commands are executed
through the CP command register (CPCR); see Section 14.4, "Command Set."
19.9.1 _
START IDMA
The _ command is used to start a transfer on an IDMA channel. The user must
START IDMA
initialize all parameters relevant for the correct operation of the channel (IDMAx_BASE
and IDMA channel parameter table) before issuing this command.
To restart the channel operation, the
pause in channel activity. The user must ensure that parameters are correct for the channel
to continue operation correctly.
The parameter ISTATE of the IDMA parameter RAM should be cleared before every issue
of a _ command.
START IDMA
An IDMA pause may occur for one of the following reasons:
• The channel is out of buffers—IDSR[OB] event is set and an interrupt is generated
to the core, if enabled.
• DONE was asserted externally and DCM[DT] = 0 (see Table 19-5.). An
IDSR[EDN] event is set and an interrupt is generated to the core, if enabled.
• _ command was issued.
STOP IDMA
• The channel has finished a transfer of a BD with the last bit (L) set.
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Source data bus.
0 The source address lies within the 60x bus.
1 The source address lies within the local or PCI buses.
In fly-by mode, should be the same as DDTB.
Reserved, should be cleared.
zero.
Note: When operating with a peripheral that accepts only single bus transactions
(transfer size < 32), data length should be a multiple of the peripheral transfer size (STS
for S/D = 10, or DTS for S/D = 01). Also, there is no error notification if the data length
does not match the buffer sizes.
Holds the address of the associated buffer. Buffers may reside in internal or external
memory. Note that if the source/destination is a device, the pointer should contain the
device address.
In fly-by mode, the pointers should contain the memory address.
Command
START
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Description
_ command can be reissued after every
IDMA
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