Figure 4-1 Dma Addressing Modes For Sci; Transmitters - Motorola DSP56600 Manual

Using the DMA
Servicing a Peripheral
4-10 Optimizing DSP56300/DSP56600 Applications
Destination
SRXL
SRXM
SRXH
X I/O Space
Figure 4-1 DMA Addressing Modes for SCI Transmitters
The following assembler code is needed for this configuration.
;================= initialize DMA channel 0
TX_BUF equ
BUF_SIZEequ
COUNT0 equ
movep
movep
movep
movep
movep
$200 ;base address of buffer with data to
;transmit
16 ;number of words in TX_BUF
((BUF_SIZE-1)<<12)+(2<<6)+0
;set the counter value for 3D mode:
;BUFF_SIZE-1 in DCOH (bits 23:12),
;(3-1=2) in DCOM (bits 11:6),
;0 in DCOL (bits 5:0).
#M_STXL,x:M_DDR0;destination base address:
;SCI Transmit Low register.
#TX_BUF,x:M_DSR0;source base address:
;address of memory transmit
;data area.
#COUNT0,x:M_DCO0;load number of transfers
before core is interrupted.
#0,x:M_DOR0 ;offset register 0,
;added every word
;(DCOL) to source address.
#1,x:M_DOR1 ;offset register 1,
;added every 3 words
;(DCOM) to source address.
Source
TX_BUF
TX_BUF + 1
TX_BUF + 2
.
.
.
TX_BUF + SIZE – 1
Y Space
AA0834
MOTOROLA