最近在学McBSP和DMA，TI的官方例程中，有一个例程是
McBSP工作在数字回环模式下，同步接收DMA通道2的数据，在这个例程中有个问题不明白
/* Wait for DMA transfer to be complete */
while (!DMA_FGETH(mhDma,DMACSR,FRAME)) {
;
}//为什么这条语句结束才表明数据收发完成?
这里的“同步”是什么意思？是McBSP模块内部进行数据传输的同时，还可以接收来自DMA的数据，如果是这样的话，接收的DMA数据是
作为写入到DXR中的数据还是其他的？
*************************************************************************************************************************
/*
* Copyright (C) 2003 Texas Instruments Incorporated
* All Rights Reserved
*/
/*
*---------main_dma3.c---------
* This example places the MCBSP in digital loopback mode and
* syncs MCBSP receive with DMA channel 2.
* The example uses predefined CSL macros and symbolic
* constants to create the initialization values needed for
* the MCBSP and DMA control registers to effect the transfer
*/
/*************************************************************************
*实验说明：将MCBSP置于数字回环模式，并且同步接收DMA通道2的数据，实验中仍然
*使用预先定义的CSL宏和符号常量来进行相关控制寄存器的初始化
*************************************************************************/
#include <stdio.h>
#include <csl_mcbsp.h>
#include <csl_dma.h>
#include <csl_irq.h>
//---------Global constants---------
#define N 128
//---------Global data definition---------
/* Define transmit and receive buffers */
#pragma DATA_SECTION(rcv,"dmaMem")
Uint16 xmt[N], rcv[N];
MCBSP_Config ConfigLoopBack16= {
MCBSP_SPCR1_RMK(
MCBSP_SPCR1_DLB_ON, /* DLB = 1 */
MCBSP_SPCR1_RJUST_RZF, /* RJUST = 0 */
MCBSP_SPCR1_CLKSTP_DISABLE, /* CLKSTP = 0 */
MCBSP_SPCR1_DXENA_NA, /* DXENA = 0 */
MCBSP_SPCR1_ABIS_DISABLE, /* ABIS = 0 */
MCBSP_SPCR1_RINTM_RRDY, /* RINTM = 0 */
0, /* RSYNCER = 0 */
MCBSP_SPCR1_RRST_DISABLE /* RRST = 0 */
),
MCBSP_SPCR2_RMK(
MCBSP_SPCR2_FREE_NO, /* FREE = 0 */
MCBSP_SPCR2_SOFT_NO, /* SOFT = 0 */
MCBSP_SPCR2_FRST_RESET, /* FRST = 0 帧同步*/
MCBSP_SPCR2_GRST_RESET, /* GRST = 0 */
MCBSP_SPCR2_XINTM_XRDY, /* XINTM = 0 */
0, /* XSYNCER = N/A */
MCBSP_SPCR2_XRST_DISABLE /* XRST = 0 */
),
MCBSP_RCR1_RMK(
MCBSP_RCR1_RFRLEN1_OF(0), /* RFRLEN1 = 0 */
MCBSP_RCR1_RWDLEN1_16BIT /* RWDLEN1 = 5 */
),
MCBSP_RCR2_RMK(
MCBSP_RCR2_RPHASE_SINGLE, /* RPHASE = 0 */
MCBSP_RCR2_RFRLEN2_OF(0), /* RFRLEN2 = 0 */
MCBSP_RCR2_RWDLEN2_8BIT, /* RWDLEN2 = 0 */
MCBSP_RCR2_RCOMPAND_MSB, /* RCOMPAND = 0 */
MCBSP_RCR2_RFIG_YES, /* RFIG = 0 */
MCBSP_RCR2_RDATDLY_0BIT /* RDATDLY = 0 数据接收延时*/
),
MCBSP_XCR1_RMK(
MCBSP_XCR1_XFRLEN1_OF(0), /* XFRLEN1 = 0 */
MCBSP_XCR1_XWDLEN1_16BIT /* XWDLEN1 = 5 发送阶段1的字长为16位*/
),
MCBSP_XCR2_RMK(
MCBSP_XCR2_XPHASE_SINGLE, /* XPHASE = 0 */
MCBSP_XCR2_XFRLEN2_OF(0), /* XFRLEN2 = 0 */
MCBSP_XCR2_XWDLEN2_8BIT, /* XWDLEN2 = 0 */
MCBSP_XCR2_XCOMPAND_MSB, /* XCOMPAND = 0 */
MCBSP_XCR2_XFIG_YES, /* XFIG = 0 */
MCBSP_XCR2_XDATDLY_0BIT /* XDATDLY = 0 */
),
MCBSP_SRGR1_RMK(
MCBSP_SRGR1_FWID_OF(1), /* FWID = 1 */
MCBSP_SRGR1_CLKGDV_OF(1) /* CLKGDV = 1 */
),
MCBSP_SRGR2_RMK(
MCBSP_SRGR2_GSYNC_FREE, /* FREE = 0 */
MCBSP_SRGR2_CLKSP_RISING, /* CLKSP = 0 */
MCBSP_SRGR2_CLKSM_INTERNAL, /* CLKSM = 1 */
MCBSP_SRGR2_FSGM_DXR2XSR, /* FSGM = 0 */
MCBSP_SRGR2_FPER_OF(15) /* FPER = 0 */
),
MCBSP_MCR1_DEFAULT,
MCBSP_MCR2_DEFAULT,
MCBSP_PCR_RMK(
MCBSP_PCR_IDLEEN_RESET, /* IDLEEN = 0 */
MCBSP_PCR_XIOEN_SP, /* XIOEN = 0 */
MCBSP_PCR_RIOEN_SP, /* RIOEN = 0 */
MCBSP_PCR_FSXM_INTERNAL, /* FSXM = 1 */
MCBSP_PCR_FSRM_EXTERNAL, /* FSRM = 0 */
MCBSP_PCR_CLKXM_OUTPUT, /* CLKXM = 1 */
MCBSP_PCR_CLKRM_INPUT, /* CLKRM = 0 */
MCBSP_PCR_SCLKME_NO, /* SCLKME = 0 */
0, /* DXSTAT = N/A */
MCBSP_PCR_FSXP_ACTIVEHIGH, /* FSXP = 0 */
MCBSP_PCR_FSRP_ACTIVEHIGH, /* FSRP = 0 */
MCBSP_PCR_CLKXP_RISING, /* CLKXP = 0 */
MCBSP_PCR_CLKRP_FALLING /* CLKRP = 0 */
),
MCBSP_RCERA_DEFAULT,
MCBSP_RCERB_DEFAULT,
MCBSP_RCERC_DEFAULT,
MCBSP_RCERD_DEFAULT,
MCBSP_RCERE_DEFAULT,
MCBSP_RCERF_DEFAULT,
MCBSP_RCERG_DEFAULT,
MCBSP_RCERH_DEFAULT,
MCBSP_XCERA_DEFAULT,
MCBSP_XCERB_DEFAULT,
MCBSP_XCERC_DEFAULT,
MCBSP_XCERD_DEFAULT,
MCBSP_XCERE_DEFAULT,
MCBSP_XCERF_DEFAULT,
MCBSP_XCERG_DEFAULT,
MCBSP_XCERH_DEFAULT
};
/* Create DMA Receive Side Configuration */
DMA_Config dmaConfig = {
DMA_DMACSDP_RMK(
DMA_DMACSDP_DSTBEN_NOBURST,
DMA_DMACSDP_DSTPACK_OFF,
DMA_DMACSDP_DST_DARAM, /*目的端口为DARAM*/
DMA_DMACSDP_SRCBEN_NOBURST,
DMA_DMACSDP_SRCPACK_OFF,
DMA_DMACSDP_SRC_PERIPH, /*源端口为 外设*/
DMA_DMACSDP_DATATYPE_16BIT
), /* DMACSDP */
DMA_DMACCR_RMK(
DMA_DMACCR_DSTAMODE_POSTINC,
DMA_DMACCR_SRCAMODE_CONST,
DMA_DMACCR_ENDPROG_ON, /*传输过程可以对配置寄存器进行编程*/
DMA_DMACCR_REPEAT_OFF,
DMA_DMACCR_AUTOINIT_OFF,
DMA_DMACCR_EN_STOP,
DMA_DMACCR_PRIO_LOW, /*通道优先级低*/
DMA_DMACCR_FS_DISABLE, /*帧同步禁止*/
DMA_DMACCR_SYNC_REVT1 /*DMA同步事件*/
), /* DMACCR */
DMA_DMACICR_RMK(
DMA_DMACICR_BLOCKIE_OFF,
DMA_DMACICR_LASTIE_OFF,
DMA_DMACICR_FRAMEIE_ON, /*半帧中断使能*/
DMA_DMACICR_FIRSTHALFIE_OFF,
DMA_DMACICR_DROPIE_OFF, /*同步事件旁落使能关闭*/
DMA_DMACICR_TIMEOUTIE_OFF /*超时中断使能关闭*/
), /* DMACICR */
(DMA_AdrPtr)(MCBSP_ADDR(DRR11)), /* DMACSSAL */
0, /* DMACSSAU */
(DMA_AdrPtr)&rcv, /* DMACDSAL */
0, /* DMACDSAU */
N, /* DMACEN */
1, /* DMACFN */
0, /* DMACFI */
0 /* DMACEI */
};
/* Define a DMA_Handle object to be used with DMA_open function */
DMA_Handle mhDma;
/* Define a MCBSP_Handle object to be used with MCBSP_open function */
MCBSP_Handle mhMcbsp;
volatile Uint16 xfrCnt = 0;
Uint16 err = 0;
Uint16 old_intm;
Uint16 xmtEventId;
//---------Function prototypes---------
/* Protoype for MCBSP transmit interrupt function */
interrupt void mcbspIsr(void);
void taskFxn(void);
//---------main routine---------
void main(void)
{
Uint16 i;
/* Initialize CSL library - This is REQUIRED !!! */
CSL_init();
/* Initialize data for transfer */
for (i = 0; i <= N - 1; i++) {
xmt[i] = i + 1;
rcv[i] = 0;
}
/* Call function to effect transfer */
taskFxn();
}
void taskFxn(void)
{
Uint16 srcAddrHi, srcAddrLo;
Uint16 dstAddrHi, dstAddrLo;
Uint16 i;
/* By default, the TMS320C55xx compiler assigns all data symbols word */
/* addresses. The DMA however, expects all addresses to be byte */
/* addresses. Therefore, we must shift the address by 2 in order to */
/* change the word address to a byte address for the DMA transfer. */
srcAddrHi = (Uint16)(((Uint32)(MCBSP_ADDR(DRR11))) >> 15) & 0xFFFFu;
srcAddrLo = (Uint16)(((Uint32)(MCBSP_ADDR(DRR11))) << 1) & 0xFFFFu;
dstAddrHi = (Uint16)(((Uint32)(&rcv)) >> 15) & 0xFFFFu;
dstAddrLo = (Uint16)(((Uint32)(&rcv)) << 1) & 0xFFFFu;
dmaConfig.dmacssal = (DMA_AdrPtr)srcAddrLo;
dmaConfig.dmacssau = srcAddrHi;
dmaConfig.dmacdsal = (DMA_AdrPtr)dstAddrLo;
dmaConfig.dmacdsau = dstAddrHi;
/* Open MCBSP Port 1 and set registers to their power on defaults */
mhMcbsp = MCBSP_open(MCBSP_PORT1, MCBSP_OPEN_RESET);
/* Get interrupt event assoicated MCBSP transmit */
xmtEventId = MCBSP_getXmtEventId(mhMcbsp);
/* Temporarily disable interrupts and clear any pending */
/* interrupts for MCBSP transmit */
old_intm = IRQ_globalDisable();
IRQ_clear(xmtEventId);
/* Enable MCBSP transmit interrupt in IER register */
IRQ_enable(xmtEventId);
/* Set Start Of Interrupt Vector Table */
IRQ_setVecs(0x10000);
/* Place address for MCBSP transmit interrupt service routine */
/* in associated vector location */
IRQ_plug(xmtEventId,&mcbspIsr);
/* Open DMA Channel 2 and set registers to their power on defaults */
mhDma = DMA_open(DMA_CHA2,DMA_OPEN_RESET);
/* Write values from configuration structure to MCBSP control regs */
MCBSP_config(mhMcbsp, &ConfigLoopBack16);
/* Write values from configuration structure to DMA control regs */
DMA_config(mhDma,&dmaConfig);
/* Enable all maskable interrupts */
IRQ_globalEnable();
/* Start MCBSP */
MCBSP_start(mhMcbsp,
MCBSP_SRGR_START|MCBSP_SRGR_FRAMESYNC,0x300u);
/* Enable DMA */
DMA_start(mhDma);
/* Take MCBSP transmit annd receive out of reset 发送和接收复位*/
MCBSP_start(mhMcbsp,
MCBSP_XMIT_START| MCBSP_RCV_START,
0);
/* Wait for DMA transfer to be complete */
while (!DMA_FGETH(mhDma,DMACSR,FRAME)) {
;
}//为什么这条语句结束才表明数据收发完成?
/*------------------------------------------*\
* Compare values 所有数据发送和接收都完毕之后，
检测数据收发有没有错误
\*------------------------------------------*/
for(i = 0; i <= N - 1; i++){
if (rcv[i] != xmt[i]){
++err;
break;
}
}
printf ("%s\n",err?"TEST FAILED" : "TEST PASSED");
/* Restore status of global interrupt enable flag */
IRQ_globalRestore(old_intm);
/* We're done with MCBSP and DMA , so close them */
MCBSP_close(mhMcbsp);
DMA_close(mhDma);
}
/* MCBSP transmit interrupt service routine */
/*MCBSP发送中断服务子程序*/
interrupt void mcbspIsr(void) {
if (xfrCnt < N) {
MCBSP_write16(mhMcbsp,xmt[xfrCnt]); /*当发送准备好后，进入中断写数据*/
++xfrCnt;
}
else {
MCBSP_FSETH(mhMcbsp,SPCR2,XRST,0);
}
}
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