//-----------------------------------------------------------------
//  名稱: 用帶SPI接口的數(shù)模轉(zhuǎn)換芯片MCP4921生成正弦波形
//-----------------------------------------------------------------
//  說明: 本例運(yùn)行時,經(jīng)MCP4921進(jìn)行數(shù)/模轉(zhuǎn)換后的輸出信號經(jīng)調(diào)理后的輸出
//        為周期為2ms,幅值為2.5V(+/-)正弦交流信號.
//
//-----------------------------------------------------------------
#include <pic.h>
#define INT8U   unsigned char
#define INT16U  unsigned int
#define _XTAL_FREQ 20000000UL  //20MHZ
//SPI使能與禁用,鎖存使能與禁用
#define SPI_EN()   RC6 = 0
#define SPI_DI()   RC6 = 1
//當(dāng)LDAC引腳直接連接低電平時下面的定義取消
//#define LDAC_EN()  RC7 = 0
//#define LDAC_DI()  RC7 = 1
//正弦波100個采樣點(diǎn)電壓對應(yīng)的數(shù)字值
//幅值為(+/-)1.25V,上移2.5V,輸出正弦電壓區(qū)間為: +3.75 ~ +1.25V
//中心點(diǎn)為+2.5V,這三個點(diǎn)(3.75,2.5,1.25)對應(yīng)的DA值為(3072,2048,1024)
const INT16U SIN_DATA[100] = 
{
    2048, 2112, 2176, 2239, 2302, 2364, 2424, 2483, 2541, 2596, 
    2649, 2700, 2748, 2794, 2837, 2876, 2912, 2945, 2974, 3000, 
    3021, 3039, 3053, 3063, 3069, 3072, 3069, 3063, 3053, 3039, 
    3021, 3000, 2974, 2945, 2912, 2876, 2837, 2794, 2748, 2700, 
    2649, 2596, 2541, 2483, 2424, 2364, 2302, 2239, 2176, 2112, 
    2048, 1984, 1920, 1857, 1794, 1732, 1672, 1613, 1555, 1500, 
    1447, 1396, 1348, 1302, 1259, 1220, 1184, 1151, 1122, 1096, 
    1075, 1057, 1043, 1033, 1027, 1024, 1027, 1033, 1043, 1057, 
    1075, 1096, 1122, 1151, 1184, 1220, 1259, 1302, 1348, 1396, 
    1447, 1500, 1555, 1613, 1672, 1732, 1794, 1857, 1920, 1984
};
INT8U d;
//SPI數(shù)據(jù)傳輸(啟動數(shù)據(jù)傳輸,然后等待傳輸結(jié)束,最后返回SSPBUF)
#define SPI_Transmit(x) { SSPBUF = x; while(!BF); d = SSPBUF; }
//-----------------------------------------------------------------
// SPI主機(jī)初始化
//-----------------------------------------------------------------
void SPI_MasterInit()
{



}
//-----------------------------------------------------------------
// 主程序
//-----------------------------------------------------------------
void main()
{ 




}

//-----------------------------------------------------------------
// 定時器中斷程序
//-----------------------------------------------------------------
void interrupt INT_ISR()
{    
    static INT8U idx = 0;          //待發(fā)送的D/A傳輸數(shù)字索引
    if (TMR2IF == 1)
    {   




    }
}