Servicing A Peripheral - Motorola DSP56600 Manual

Using the DMA

Servicing a Peripheral

4-6 Optimizing DSP56300/DSP56600 Applications
;DAM[5:3]101
;DAM[2:0]000
;DS[3:2]01
;DS[1:0]01
movep
;============ main program
...
bset
...
;============ interrupt definition
org
jsr
4.4 SERVICING A PERIPHERAL
DMA transfers can be triggered by peripherals and can transfer data
to and from them, thus giving the user a powerful alternative for
driving peripherals. Examples for interrupt-driven core handling
were given earlier in Section 3. Using the DMA to handle
peripheral requests has the following advantages:
1. Saves core MIPS because the DMA is triggered
independently and transfers the data in parallel to the core
2. Frees core address registers that previously had to be
reserved as pointers to the data buffers to keep them
available for processing a fast interrupt
3. Decreases the latency between peripheral triggering and
actual handling by using the DMA (under the same
circumstances, i.e., no other triggers/interrupts with higher
priorities)
destination address post-increment
source address: 2D with offset register 0
transfer destination: y memory.
transfer source: y memory.
#$580285,x:M_DCR0;load control register.
#23,x:M_DCR0
p:I_DMA0
<USE_COMPACT_DATA
;trigger transfer
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