unsigned char code SinWave[] = { //正弦波波表
127, 152, 176, 198, 217, 233, 245, 252,
255, 252, 245, 233, 217, 198, 176, 152,
127, 102, 78, 56, 37, 21, 9, 2,
0, 2, 9, 21, 37, 56, 78, 102
};
unsigned char code TriWave[] = { //三角波波表
0, 16, 32, 48, 64, 80, 96, 112,
128, 144, 160, 176, 192, 208, 224, 240,
255, 240, 224, 208, 192, 176, 160, 144,
128, 112, 96, 80, 64, 48, 32, 16
};
unsigned char code SawWave[] = { //锯齿波表
0, 8, 16, 24, 32, 40, 48, 56,
64, 72, 80, 88, 96, 104, 112, 120,
128, 136, 144, 152, 160, 168, 176, 184,
192, 200, 208, 216, 224, 232, 240, 248
};
unsigned char code *pWave; //波表指针
unsigned char T0RH = 0; //T0 重载值的高字节
unsigned char T0RL = 0; //T0 重载值的低字节
unsigned char T1RH = 1; //T1 重载值的高字节
unsigned char T1RL = 1; //T1 重载值的低字节
void ConfigTimer0(unsigned int ms);
void SetWaveFreq(unsigned char freq);
extern void KeyScan();
extern void KeyDriver();
extern void I2CStart();
extern void I2CStop();
extern bit I2CWrite(unsigned char dat);
void main(){
EA = 1; //开总中断
ConfigTimer0(1); //配置 T0 定时 1ms
pWave = SinWave; //默认正弦波
SetWaveFreq(10); //默认频率 10Hz
while (1){
KeyDriver(); //调用按键驱动
}
}
/* 按键动作函数，根据键码执行相应的操作，keycode-按键键码 */
void KeyAction(unsigned char keycode){
static unsigned char i = 0;
if (keycode == 0x26){ //向上键，切换波形
//在 3 种波形间循环切换
if (i == 0){
i = 1;
pWave = TriWave;
}else if (i == 1){
i = 2;
pWave = SawWave;
}else{
i = 0;
pWave = SinWave;
}
}
}
/* 设置 DAC 输出值，val-设定值 */
void SetDACOut(unsigned char val){
I2CStart();
if (!I2CWrite(0x48<<1)){ //寻址 PCF8591，如未应答，则停止操作并返回
I2CStop();
return;
}
I2CWrite(0x40); //写入控制字节
I2CWrite(val); //写入 DA 值
I2CStop();
}
/* 设置输出波形的频率，freq-设定频率 */
void SetWaveFreq(unsigned char freq){
unsigned long tmp;
tmp = (11059200/12) / (freq*32); //定时器计数频率，是波形频率的 32 倍
tmp = 65536 - tmp; //计算定时器重载值
tmp = tmp + 33; //修正中断响应延时造成的误差
T1RH = (unsigned char)(tmp>>8); //定时器重载值拆分为高低字节
T1RL = (unsigned char)tmp;
TMOD &= 0x0F; //清零 T1 的控制位
TMOD |= 0x10; //配置 T1 为模式 1
TH1 = T1RH; //加载 T1 重载值
TL1 = T1RL;
ET1 = 1; //使能 T1 中断
PT1 = 1; //设置为高优先级
TR1 = 1; //启动 T1
}
/* 配置并启动 T0，ms-T0 定时时间 */
void ConfigTimer0(unsigned int ms){
unsigned long tmp; //临时变量
tmp = 11059200 / 12; //定时器计数频率
tmp = (tmp * ms) / 1000; //计算所需的计数值
tmp = 65536 - tmp; //计算定时器重载值
tmp = tmp + 28;//补偿中断响应延时造成的误差
T0RH = (unsigned char)(tmp>>8); //定时器重载值拆分为高低字节
T0RL = (unsigned char)tmp;
TMOD &= 0xF0; //清零 T0 的控制位
TMOD |= 0x01; //配置 T0 为模式 1
TH0 = T0RH; //加载 T0 重载值
TL0 = T0RL;
ET0 = 1; //使能 T0 中断
TR0 = 1; //启动 T0
}
/* T0 中断服务函数，执行按键扫描 */
void InterruptTimer0() interrupt 1{
TH0 = T0RH; //重新加载重载值
TL0 = T0RL;
KeyScan(); //按键扫描
}
/* T1 中断服务函数，执行波形输出 */
void InterruptTimer1() interrupt 3{
static unsigned char i = 0;
TH1 = T1RH; //重新加载重载值
TL1 = T1RL;
//循环输出波表中的数据
SetDACOut(pWave[i]);
i++;
if (i >= 32){
i = 0;
}
}
