msp430工作笔记3
(一),频率计的设计
本文引用地址://m.amcfsurvey.com/article/201611/316300.htm2,测周法:
(1)可以使用定时器的输入捕获功能,捕获上升沿或下降沿,然后就可以计算出信号的周期,从而得出频率。
(2)也可以把待测信号接到IO上,然后用无限循环不停的查询电平的高低,从而得出信号的周期。丁老师建议:以丁老师的经验,这种方法测量的精度比用捕获中断的精度要高,因为中断的进入和退出都要占用时间。
(3)但这种侧周法适用于低频信号频率的测量,对于高频信号精度不好。
3,测频法:
4,等精度测频:
(2) 如果Timer0_A用于其他用途的话,也可以接一个计数器,然后把计数值在输入给单片机(如小车上测速所采用的方法)。
(3) 目前这个方案还在完善中,但初步试验表示,精度可以达到很高(10的-4以上)
(二),DAC0832的使用
电路如下:
其中0832工作于单缓冲模式,输入寄存器受控,DAC寄存器直通
一个基本的0832控制程序如下:
#include <msp430g2553.h>
#define uint unsigned int
#define uchar unsigned char
//dac0832pin define
#define CS_SET P2OUT |= BIT6
#define CS_CLR P2OUT &= ~BIT6
#define WR_SET P2OUT |= BIT7
#define WR_CLR P2OUT &= ~BIT7
#define DI P1OUT
//1延时
//#define CPU_F ((double)16000000)//cpu frequency16000000
#define CPU_F ((double)1000000)//cpu frequency1000000
#define delay_us(x) __delay_cycles((long)(CPU_F*(double)x/1000000.0))
#define delay_ms(x) __delay_cycles((long)(CPU_F*(double)x/1000.0))
void write_dac(uint data)
{
CS_CLR;
DI = data;
WR_CLR;
delay_us(1);
WR_SET;
CS_SET;
}
void IO_init()
{
P1DIR = 0xff;
}
void DCO_init()
{
}
void main(void)
{
// uintadc_data=0;
WDTCTL = WDTPW + WDTHOLD;
IO_init();
DCO_init();
write_dac(0xff);
for(;;)
{
write_dac(0xff);
delay_ms(1);
write_dac(0xc0);
delay_ms(1);
write_dac(0x7f);
delay_ms(1);
write_dac(0x3f);
delay_ms(1);
write_dac(0x00);
delay_ms(1);
}
}
#include
#include "ser_12864.h"
//dac0832 pin define
#define CS_SET P2OUT |= BIT6
#define CS_CLR P2OUT &= ~BIT6
#define WR_SET P2OUT |= BIT7
#define WR_CLR P2OUT &= ~BIT7
#define DI P1OUT
uint key=0;
uchar s_step[]=
uchar s_sin[] =
uchar s_square[]=
uchar s_saw[]=
uchar s_triangular[]={"triangular"};
const uchar sin_a[256]={0x80,0x83,0x86,0x89,0x8c,0x8f,0x92,0x95,0x98,0x9c,
0x9f,0xa2,0xa5,0xa8,0xab,0xae,0xb0,0xb3,0xb6,0xb9,0xbc,0xbf,0xc1,0xc4,0xc7,
0xc9,0xcc,0xce,0xd1,0xd3,0xd5,0xd8,0xda,0xdc,0xde,0xe0,0xe2,0xe4,0xe6,0xe8,0xea,
0xec,0xed,0xef,0xf0,0xf2,0xf3,0xf4,0xf6,0xf7,0xf8,0xf9,0xfa,0xfb,0xfc,0xfc,0xfd,
0xfe,0xfe,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xfe,0xfe,0xfd,
0xfc,0xfc,0xfb,0xfa,0xf9,0xf8,0xf7,0xf6,0xf5,0xf3,0xf2,0xf0,0xef,0xed,0xec,0xea,
0xe8,0xe6,0xe4,0xe3,0xe1,0xde,0xdc,0xda,0xd8,0xd6,0xd3,0xd1,0xce,0xcc,0xc9,0xc7,
0xc4,0xc1,0xbf,0xbc,0xb9,0xb6,0xb4,0xb1,0xae,0xab,0xa8,0xa5,0xa2,0x9f,0x9c,0x99,
0x96,0x92,0x8f,0x8c,0x89,0x86,0x83,0x80,0x7d,0x79,0x76,0x73,0x70,0x6d,0x6a,0x67,
0x64,0x61,0x5e,0x5b,0x58,0x55,0x52,0x4f,0x4c,0x49,0x46,0x43,0x41,0x3e,0x3b,0x39,
0x36,0x33,0x31,0x2e,0x2c,0x2a,0x27,0x25,0x23,0x21,0x1f,0x1d,0x1b,0x19,0x17,0x15,0x14,
0x12,0x10,0xf,0xd,0xc,0xb,0x9,0x8,0x7,0x6,0x5,0x4,0x3,0x3,0x2,0x1,0x1,0x0,0x0,0x0,0x0,
0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x1,0x1,0x2,0x3,0x3,0x4,0x5,0x6,0x7,0x8,0x9,0xa,0xc,0xd,
0xe,0x10,0x12,0x13,0x15,0x17,0x18,0x1a,0x1c,0x1e,0x20,0x23,0x25,0x27,0x29,0x2c,0x2e,
0x30,0x33,0x35,0x38,0x3b,0x3d,0x40,0x43,0x46,0x48,0x4b,0x4e,0x51,0x54,0x57,0x5a,0x5d,
0x60,0x63,0x66,0x69,0x6c,0x6f,0x73,0x76,0x79,0x7c};
void IO_interrupt_init()
{
}
void write_dac(uchar data)
{
CS_CLR;
DI = data;
WR_CLR;
delay_us(1);
WR_SET;
CS_SET;
}
void saw()
{
uchar i=0;
for(i=0;i<255;i++)
{
write_dac(i);
}
}
void triangular()
{
uchar i=0;
for(i=0;i<255;i++)
{
write_dac(i);
}
for(i=255;i>0;i--)
{
write_dac(i);
}
}
void square()
{
write_dac(0xff);
delay_us(500);
write_dac(0x00);
delay_us(500);
}
void sin()
{
uchar i;
for(i=0;i<255;i++)
{
write_dac(sin_a[i]);
}
}
void step()
{
write_dac(0xff);
delay_us(500);
write_dac(0xc0);
delay_us(500);
write_dac(0x7f);
delay_us(500);
write_dac(0x3f);
delay_us(500);
write_dac(0x00);
delay_us(500);
}
void main(void)
WDTCTL = WDTPW + WDTHOLD;
uchar s1[] ={"
//
}
// Port 2 interrupt service routine
#pragma vector=PORT2_VECTOR
__interrupt void Port_1(void)
{
}
//由于按键较少,所以这里各种波形的各个参数都是提前设定好的,不能再设定,
//应该可以在IO中断里利用中断嵌套,再次检测按键来设置参数,频率,占空比....,还没有完善
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