树莓派本身没有AD/DA功能，如果树莓派外接模拟传感器，则必须外接AD/DA功能扩展板才能用。Pioneer 600扩展带有AD/DA芯片PCF8591,pcf8591带1通道8位DA,4通道8位AD,通过I2C控制。
一、DAC
1、bcm2835程序
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 |
#include <bcm2835.h> #include <stdio.h> #include <unistd.h> int main(int argc, char **argv) { char Buf[]={0,0}; unsigned char value=0; if (!bcm2835_init())return 1; bcm2835_i2c_begin(); bcm2835_i2c_setSlaveAddress(0x48); bcm2835_i2c_set_baudrate(10000); printf("start..........\n"); while(1) { Buf[0] = 0x40; Buf[1] = value++; bcm2835_i2c_write(Buf,2); printf("AOUT: %d\n",value); bcm2835_delay(20); } bcm2835_i2c_end(); bcm2835_close(); return 0; } |
编译并执行
gcc –Wall pcf8591.c –o pcf8591 –lbcm2835
sudo ./ pcf8591
2、Python程序
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 |
#!/usr/bin/python # -*- coding:utf-8 -*- import smbus import time address = 0x48 cmd = 0x40 value = 0 bus = smbus.SMBus(1) while True: bus.write_byte_data(address,cmd,value) value += 1 if value == 256: value =0 print("AOUT:%3d" %value) time.sleep(0.01) |
执行程序
sudo python pcf8591
3、wiringPi程序
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 |
#include <wiringpi.h> #include <pcf8591.h> #include <stdio.h> #define Address 0x48 #define BASE 64 #define A0 BASE+0 #define A1 BASE+1 #define A2 BASE+2 #define A3 BASE+3 int main(void) { unsigned char value; wiringPiSetup(); pcf8591Setup(BASE,Address); while(1) { analogWrite(A0,value); printf("AOUT: %d\n",value++); delay(20); } } |
编译并执行程序
gcc –Wall pcf8591.c –o pcf8591 –lbcm2835 -lwiringPi
sudo ./ pcf8591
二、ADC
1、bcm2835程序
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 |
#include <bcm2835.h> #include <stdio.h> #include <unistd.h> int main(int argc, char **argv) { char Buf[]={0}; unsigned char i; if (!bcm2835_init())return 1; bcm2835_i2c_begin(); bcm2835_i2c_setSlaveAddress(0x48); bcm2835_i2c_set_baudrate(10000); printf("start..........\n"); while(1) { for(i = 0;i < 4;i++) { Buf[0] = i; bcm2835_i2c_write_read_rs(Buf,1,Buf,1); bcm2835_i2c_read (Buf,1); printf("AIN%d:%5.2f ",i,(double)Buf[0]*3.3/255); } printf("\n"); bcm2835_delay(100); } bcm2835_i2c_end(); bcm2835_close(); return 0; } |
编译并执行
gcc –Wall pcf8591.c –o pcf8591 –lbcm2835
sudo ./ pcf8591
2、Python程序
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 |
#!/usr/bin/python # -*- coding:utf-8 -*- import smbus import time address = 0x48 A0 = 0x40 A1 = 0x41 A2 = 0x42 A3 = 0x43 bus = smbus.SMBus(1) while True: bus.write_byte(address,A0) value = bus.read_byte(address) print("AOUT:%1.3f " %(value*3.3/255)) time.sleep(0.1) |
执行程序
sudo python pcf8591
3、wiringPi程序
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 |
#include <wiringpi.h> #include <pcf8591.h> #include <stdio.h> #define Address 0x48 #define BASE 64 #define A0 BASE+0 #define A1 BASE+1 #define A2 BASE+2 #define A3 BASE+3 int main(void) { int value; wiringPiSetup(); pcf8591Setup(BASE,Address); while(1) { value = analogRead(A0); printf("Analoge: %dmv\n",value*3300/255); delay(1000); } } |
编译并执行程序
gcc –Wall pcf8591.c –o pcf8591 -lwiringPi
sudo ./ pcf8591
