S3C2440 Mini 2440 DMA方法完成Uart串口通讯

DMA service mode：single service＆Whole service。前一形式下，一次DMA恳求完结一项原子操作，而且transfer count的值减1。后一形式下，一次DMA恳求完结一批原子操作，直到transfer count等于0一共完结一次全体服务。详细对应DCON[27]。

DMA DREQ/DACK PROTOCOL：DMA恳求和应对的协议有两种，Demond mode 和 Handshake mode。两者对Request和Ack的时序界说有所不同：

在Demond形式下，假如DMA完结一次恳求后假如Request依然有用，那么DMA就以为这是下一次DMA恳求，并当即开端下一次的传输；

在Handshake形式下，DMA完结一次恳求后等候Request信号无效，假如Request无效，DMA会无效ACK两个时钟周期，再等候下一次Request。

/*

功用：用DMA方法完结串口传输，
将字符串数据经过DMA0通道传递给UTXH0，然后在终端
显现。数据传输完后，DMA0发生中止，LED1亮。

Mini2440 调试经过
2012-08-05
*/
#include “2440addr.h”
#define MDIV 92
#define SDIV 1
#define PDIV 1
#define HDIVN 2
#define PDIVN 1
#define PCLK_ 50000000
#define Led1_on() {rGPBDAT&=(~(1<<5)); }
char *SendBuffer = “Hello world!” ; //source data

/*LED 初始化/
void Led_init()
{
rGPBCON &=~((3<<10) | (3<<12) | (3<<14) | (3<<16)|(3<<0));
rGPBCON |=((1<<10) | (1<<12) | (1<<14) | (1<<16)|(1<<0));
rGPBUP &=~((1<<5) | (1<<6) | (1<<7) | (1<<8)|(1<<0));
rGPBDAT =0xfffe;
}

/*UART0 io口初始化/
void Uart0_io_init() //uart io port
{
rGPHCON =0xa0; //gph2,gph3 used for txd0,rxd0.
rGPHUP=0x0; //enable the pull up function
}

/*UART0装备/
void Uart0_init(int bandrate)
{
rULCON0 |=0x3; //8-bit data ,1bit stop
rUCON0 |=((1<<0) | (1<<3) | (2<<10) ); //used pclk as the clock, transmit use DMA mode , receive use polling mode
rUBRDIV0=(int)(PCLK_/(bandrate*16))-1 ; //bandrate is 115200

}

/*时钟装备/
void Clk_init( )
{
rCLKCON |=(1<<10); //enable uart0 used pclk
rLOCKTIME=0xffff; //locktime
rCLKCON |=(1<<13); //gpio enable pclk
rCLKDIVN =((PDIVN<<0) | (HDIVN<<1)); //1:4:8
rMPLLCON |=((MDIV<<12) | (PDIV<<4) | (SDIV<<0)); // f_out=400MHZ
//__asm{
// mrc p15, 0, r1, c1, c0, 0
// orr r1, r1, #0xc0000000
//mcr p15, 0, r1, c1, c0, 0
// }
}

/*DMA初始化*/
void Dma_init()
{
rGPBCON |=((1<<19)|(1<<21)); //GPB9,10 used for nXDACK0,nXDREQ0
rDISRC0=(U32)SendBuffer; //source data address
rDISRCC0 |=((0<<1)|(0<<0)); //address increment , the source is in the AHB
rDIDST0=(U32)UTXH0; //destination is UTXH0
rDIDSTC0 |=((0<<2)|(1<<1)|(1<<0)); //address not change , APB , enable interrupt

rDCON0 |=(1<<31)|(0<<30)|(1<<29)|(0<<28)|(0<<27)|(1<<24)|(1<<23)|(1<<22)|(0<<20)|(12);
//Handshake mode, PCLK synchronization ,enable dma interrupt , unit transfer , single service ,
//UART0 is the request source, H/W request mode ,disable auto reload , Byte transmit ,12 Byte data
rDMASKTRIG0=(0<<2)|(1<<1)|(0<<0); //start dma transmit
}

/DMA中止初始化*/
void Dma_eint()
{
rINTMSK &=~(1<<17); //open the dma0 interrupt
}

/DMA中止服务函数*/
void __irq Dma_isr()
{
rSRCPND|=(1<<17); //clear the srcpnd
rINTPND |=(1<<17); //clear the int pnd
Led1_on();
}

int Main()
{
Clk_init();
Led_init();
Uart0_io_init();
Uart0_init(115200);
Dma_eint();
pISR_DMA0=(U32) Dma_isr;
Dma_init();
while(1)
{
;
}
return 0;
}