00. Table of Contents
Article Directory
01. Introduction to DAC
The DAC module (digital/analog conversion module) of STM32F4 is a 12-bit digital input, voltage output type DAC. The DAC can be configured in 8-bit or 12-bit mode, and it can also be used with a DMA controller. When the DAC works in 12-bit mode, the data can be set to left-justified or right-justified. The DAC module has 2 output channels, and each channel has a separate converter. In dual DAC mode, two channels can be converted independently, or they can be converted simultaneously and update the output of the two channels simultaneously. DAC can input reference voltage Vref+ (shared by ADC) through the pin to obtain more accurate conversion results.
The main features of STM32F4's DAC module are:
① 2 DAC converters: each converter corresponds to one output channel
② 8-bit or 12-bit monotonic output
③ Left-aligned or right-aligned data in 12-bit mode
④ Synchronous update function
⑤ Noise waveform Generate
⑥ Triangular waveform generation
⑦ Dual DAC channels can be converted simultaneously or separately
⑧ Each channel has DMA function
02. Hardware Module
The hardware resources used are:
1) LED indicator DS0
2) KEY_UP and KEY1 buttons
3) serial port
4) TFTLCD module
5) ADC
6) DAC
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03. Programming
dac.h file
#ifndef __DAC_H
#define __DAC_H
#include "sys.h"
void Dac1_Init(void); //DAC通道1初始化
void Dac1_Set_Vol(u16 vol); //设置通道1输出电压
#endif
dac.c file
#include "dac.h"
//DAC通道1输出初始化
void Dac1_Init(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
DAC_InitTypeDef DAC_InitType;
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);//使能GPIOA时钟
RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC, ENABLE);//使能DAC时钟
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;//模拟输入
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_DOWN;//下拉
GPIO_Init(GPIOA, &GPIO_InitStructure);//初始化
DAC_InitType.DAC_Trigger=DAC_Trigger_None; //不使用触发功能 TEN1=0
DAC_InitType.DAC_WaveGeneration=DAC_WaveGeneration_None;//不使用波形发生
DAC_InitType.DAC_LFSRUnmask_TriangleAmplitude=DAC_LFSRUnmask_Bit0;//屏蔽、幅值设置
DAC_InitType.DAC_OutputBuffer=DAC_OutputBuffer_Disable ; //DAC1输出缓存关闭 BOFF1=1
DAC_Init(DAC_Channel_1,&DAC_InitType); //初始化DAC通道1
DAC_Cmd(DAC_Channel_1, ENABLE); //使能DAC通道1
DAC_SetChannel1Data(DAC_Align_12b_R, 0); //12位右对齐数据格式设置DAC值
}
//设置通道1输出电压
//vol:0~3300,代表0~3.3V
void Dac1_Set_Vol(u16 vol)
{
double temp=vol;
temp/=1000;
temp=temp*4096/3.3;
DAC_SetChannel1Data(DAC_Align_12b_R,temp);//12位右对齐数据格式设置DAC值
}
main.c file
int main(void)
{
u16 adcx;
float temp;
u8 t=0;
u16 dacval=0;
u8 key;
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);//设置系统中断优先级分组2
delay_init(168); //初始化延时函数
uart_init(115200); //初始化串口波特率为115200
LED_Init(); //初始化LED
LCD_Init(); //LCD初始化
Adc_Init(); //adc初始化
KEY_Init(); //按键初始化
Dac1_Init(); //DAC通道1初始化
POINT_COLOR=RED;
LCD_ShowString(30,50,200,16,16,"Explorer STM32F4");
LCD_ShowString(30,70,200,16,16,"DAC TEST");
LCD_ShowString(30,90,200,16,16,"ATOM@ALIENTEK");
LCD_ShowString(30,110,200,16,16,"2014/5/6");
LCD_ShowString(30,130,200,16,16,"WK_UP:+ KEY1:-");
POINT_COLOR=BLUE;//设置字体为蓝色
LCD_ShowString(30,150,200,16,16,"DAC VAL:");
LCD_ShowString(30,170,200,16,16,"DAC VOL:0.000V");
LCD_ShowString(30,190,200,16,16,"ADC VOL:0.000V");
DAC_SetChannel1Data(DAC_Align_12b_R,dacval);//初始值为0
while(1)
{
t++;
key=KEY_Scan(0);
if(key==WKUP_PRES)
{
if(dacval<4000)dacval+=200;
DAC_SetChannel1Data(DAC_Align_12b_R, dacval);//设置DAC值
}else if(key==2)
{
if(dacval>200)dacval-=200;
else dacval=0;
DAC_SetChannel1Data(DAC_Align_12b_R, dacval);//设置DAC值
}
if(t==10||key==KEY1_PRES||key==WKUP_PRES) //WKUP/KEY1按下了,或者定时时间到了
{
adcx=DAC_GetDataOutputValue(DAC_Channel_1);//读取前面设置DAC的值
LCD_ShowxNum(94,150,adcx,4,16,0); //显示DAC寄存器值
temp=(float)adcx*(3.3/4096); //得到DAC电压值
adcx=temp;
LCD_ShowxNum(94,170,temp,1,16,0); //显示电压值整数部分
temp-=adcx;
temp*=1000;
LCD_ShowxNum(110,170,temp,3,16,0X80); //显示电压值的小数部分
adcx=Get_Adc_Average(ADC_Channel_5,10); //得到ADC转换值
temp=(float)adcx*(3.3/4096); //得到ADC电压值
adcx=temp;
LCD_ShowxNum(94,190,temp,1,16,0); //显示电压值整数部分
temp-=adcx;
temp*=1000;
LCD_ShowxNum(110,190,temp,3,16,0X80); //显示电压值的小数部分
LED0=!LED0;
t=0;
}
delay_ms(10);
}
}
04. Result verification
At the same time, the continuous flashing of DS0 indicates that the program is running. At this time, we can see that the output voltage increases by pressing the KEY_UP button, while pressing KEY1 will decrease.
05. Reserved
06. Appendix
6.1 [STM32] STM32 series tutorial summary
Website: [STM32] STM32 series tutorial summary
07. Statement
This tutorial refers to the "STM32 F4 Development Guide" of Punctual Atom