Motorola MPC8260 User Manual
MOTOROLA
Chapter 18. SDMA Channels and IDMA Emulation
18-29
Part IV. Communications Processor Module
Table 18-14 describes parallel I/O register programming for port D (optional).
18.12 IDMA Programming Examples
These programming examples demonstrate the use of most of the different modes and
conÞgurations of the IDMA channels.
conÞgurations of the IDMA channels.
18.12.1 Peripheral-to-Memory Mode (60x Bus to Local Bus)ÑIDMA2
In the example in Table 18-15, the IDMA2 channel reads 8 bytes per DREQ assertion from
a Þxed address peripheral located on the 60x bus into the internal buffer. When there is
enough data in the internal buffer, it writes one burst to the memory located on the local
bus. The internal buffer size is set to 64 bytes to handle maximum transfer of a single burst.
The IDMA2 channel asserts DONE on the last read transfer of the last BD to notify the
peripheral that there is no data left to transfer.
a Þxed address peripheral located on the 60x bus into the internal buffer. When there is
enough data in the internal buffer, it writes one burst to the memory located on the local
bus. The internal buffer size is set to 64 bytes to handle maximum transfer of a single burst.
The IDMA2 channel asserts DONE on the last read transfer of the last BD to notify the
peripheral that there is no data left to transfer.
Table 18-14. Parallel I/O Register ProgrammingÑPort D
Channel
Signal
Pin
PPARD
PDIRD
PODRD
PSORD
Default
IDMA1
DACK1 (O)
PD[6]
1
1
0
1
Ñ
DONE1 (I/O)
PD[5]
1
0
1
1
VDD
Table 18-15. Example: Peripheral-to-Memory ModeÑIDMA2
Important Init Values
Description
DCM(FB) = 0
Not in ßy-by mode.
DCM(LP) = 0
Transfers to memory have middle CPM request priority. The destination bus is not overloaded.
DCM(DMA_WRAP) =
000
000
The internal buffer is 64 bytes long to support 32-byte transfers to memory on the destination
bus (one 60x burst) on steady-state of work.
bus (one 60x burst) on steady-state of work.
DCM(ERM) = 1
Transfers from peripheral are initiated by DREQ. DONE assertion is supported.
DCM(DT) = 0
Assertion of DONE by the peripheral causes the transfer to be terminated, after writing all the
data in the internal buffer to memory, interrupt EDN is set to the core, IDMA channel is
stopped. additional DREQ assertions are ignored, until
data in the internal buffer to memory, interrupt EDN is set to the core, IDMA channel is
stopped. additional DREQ assertions are ignored, until
START
_
IDMA
command is issued.
DCM(S/D) = 10
Peripheral-to-memory mode. DONE DREQ and DACK are connected to the peripheral.
DCM(SINC) = 0
The peripheral address are not incremented after transfers, Þxed location.
DCM(DINC) = 1
The memory address is incremented after every transfer.
DPR_BUF = 0x0DC0
Initiated to address aligned to 64 (bit[5Ð0]= 00000).
IBASE = IBDPTR =
0x0030
0x0030
The current BD pointer is set to the BD table base address (aligned 16 -bits[3Ð0] = 0).
STS = 8 (0x0008)
Transfers from peripheral are always single 8-byte accesses.
DTS = 32 (0x0020)
Transfers to memory are 32 bytes long (60x bursts) on steady-state of work.
Every BD(SDTB) = 1
Peripheral is on the 60x bus.
Every BD(DDTB) = 0
Memory is on the local bus.