Texas Instruments TMS320C3x 사용자 설명서

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.