Texas Instruments TMS320C3x - Manual (Page 454)

DMA Controller
12-75 Peripherals
Example 12–8. Array Initialization With DMA
* TITLE: ARRAY INITIALIZATION WITH DMA
*
.GLOBAL START
.DATA
DMA .WORD 808000H
; DMA GLOBAL-CONTROL REG ADDRESS
RESET .WORD 0C40H ; DMA GLOBAL-CONTROL REG RESET VALUE
CONTROL .WORD 0C43H ; DMA GLOBAL-CONTROL REG INITIALIZATION
SOURCE .WORD ZERO ; DATA SOURCE ADDRESS
DESTIN .WORD _ARRAY ; DATA DESTINATION ADDRESS
COUNT .WORD 128 ; NUMBER OF WORDS TO TRANSFER
ZERO .FLOAT 0.0 ; ARRAY INITIALIZATION VALUE 0.0 = 0x80000000
.BSS _ARRAY,128 ; DATA ARRAY LOCATED IN .BSS SECTION
.TEXT
START LDP DMA ; LOAD DATA PAGE POINTER
LDI @DMA,AR0 ; POINT TO DMA GLOBAL CONTROL REGISTER
LDI @RESET,R0 ; RESET DMA
STI R0,*AR0
LDI @SOURCE,R0
; INITIALIZE DMA SOURCE-ADDRESS REGISTER
STI R0,*+AR0(4)
LDI @DESTIN,R0
; INITIALIZE DMA DESTINATION-ADDRESS REGISTER
STI R0,*+AR0(6)
LDI @COUNT,R0
; INITIALIZE DMA TRANSFER COUNTER REGISTER
STI R0,*+AR0(8)
OR 400H,IE
; ENABLE INTERRUPT FROM DMA TO CPU
OR 2000H,ST ; ENABLE CPU INTERRUPTS GLOBALLY
LDI @CONTROL,R0 ; INITIALIZE DMA GLOBAL CONTROL REGISTER
STI R0,*AR0 ; START DMA TRANSFER
BU $
.END
Example 12–9 sets up the DMA to transfer data (128 words) from the serial
port 0 input register to an array buffer with serial port receive interrupt (RINT0).
The DMA sends an interrupt to the CPU when the data transfer completes.
Serial port 0 is initialized to receive 32-bit data words with an internally generated
receive-bit clock and a bit-transfer rate of 8H1 cycles/bit.
This program assumes previous initialization of the CPU interrupt vector table
(specifically the DMA-to-CPU interrupt). The serial port interrupt directly affects
only the DMA; no CPU serial-port interrupt-vector setting is required.