pic单片机io口怎么设置(PIC单片机PIC16F1786编程之ADC)(1)

PIC16F1786

初始化:

void ADC_Init(void)

{

ANSELA = 0b00000001; //AN0 for AD

ANSELB = 0b00000000; //数字IO

ADCON2 = 0b00001111; //反向输入端为ADNREF

ADCON1 = 0b10010000; //右对齐 VDD VSS FRC

ADCON0 = 0b00000001; //ADON = 1 12bit

}

ANSELA:PORTA ANALOG SELECT REGISTER 0x18C

pic单片机io口怎么设置(PIC单片机PIC16F1786编程之ADC)(2)

0=Digital I/O;

1=Analog Input;

如果设置一个pin为Analog Input,其相应的TRIS控制位必须先设为Input mode

ANSELA = 0b00000001;

该语句设置AN0,即管脚2(RA0)为Analog Input

在main()函数中调用ADC_Init(void) 之前,有:

TRISA = 0b11000011;即是RA0、RA1、RA6、RA7为Input Mode

RA2、RA3、RA4、RA5为Output Mode

ANSELB:PORTB ANALOG SELECT REGISTER 0x18D

R/W-1/1 U-0 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1 R/W-1/1
-ANSB6ANSB5ANSB4ANSB3ANSB2ANSB1ANSB0
bit7 bit0
说明:

R=Readable bit, W=Writable bit, U=Unimplemented bit,read as "0",

u=Bit is unchanged, x=Bit is unknown, -n/n=Value at POR and BOR/value at all other resets,

'1'=Bit is set, '0=Bit is cleaed.

RB<6:0>:

0=Digital I/O;

1=Analog Input;

ADCON2:ADC Control REGISTER 2 0X09F

R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0
TRIGSEL<3:0>CHSN<3:0>
bit7 bit0
说明:

R=Readable bit, W=Writable bit, U=Unimplemented bit,read as "0",

u=Bit is unchanged, x=Bit is unknown, -n/n=Value at POR and BOR/value at all other resets,

'1'=Bit is set, '0=Bit is cleaed.

bit7-4 TRIGSEL<3:0> :Auto-conversion Trigger Source Selection Bits:

1111 = Reserved,Auto-conversion Trigger disabled;

1110 = Reserved,Auto-conversion Trigger disabled;

1101 = Reserved,Auto-conversion Trigger disabled;

1100 = Reserved;

1011 = Reserved;

1010 = Reserved;

1001 = PSMC2 falling edge event;(Programmable Switch Mode Control)

1000 = PSMC2 rising edge event;

0111 = PSMC2 period match event;

0110 = PSMC1 falling edge event;

0101 = PSMC1 rising edge event;

0100 = PSMC1 period match event;

0011 = Reserved,Auto-conversion Trigger disabled;

0010 = CCP2,Auto-conversion Trigger;

0001 = CCP1,Auto-conversion Trigger;

0000 = Disabled;

bit3-0 CHSN<3:0>:Negative Differential Input Channel Select Bits;

When ADON =0,all multiplexer inputs are disconnected。

1111 = ADC Negative reference,selected by ADNREF;

1110 = No Channel Connected;

1101 = AN13;

1100 = AN12;

1011 = AN11;

1010 = AN10;

1001 = AN9;

1000 = AN8;

0111 = Reserved;

0110 = Reserved;

0101 = Reserved;

0100 = AN4;

0011 = AN3;

0010 = AN2;

0001 = AN1;

0000 = AN0;

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

ADCON2 = 0b00001111;

该语句设置ADC Control Register 2,即AD 变换控制寄存器2。

TRIGSEL<3:0> = 0000:禁止自动触发。

CHSN<3:0> = 1111:反向输入端为ADNREF。

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

ADCON1:ADC Control REGISTER 1 0x09E

R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 U-0 R/W-0/0 R/W-0/0 R/W-0/0
ADFMADCS<2:0>ADNREFADPREF<1:0>
bit7 bit0
说明:

R=Readable bit, W=Writable bit, U=Unimplemented bit,read as "0",

u=Bit is unchanged, x=Bit is unknown, -n/n=Value at POR and BOR/value at all other resets,

'1'=Bit is set, '0=Bit is cleaed.

bit7 ADFM :ADC Result Format Select Bit(ADC 结果格式设置)

1 = 2‘s complement format(补码格式2进制);

0 = Sign-magnitude result format(符号数格式);

bit6-4 ADCS<2:0>:ADC Conversion Clock Select Bits:

111 = FRC(clock supplied from a dadicated FRC Oscillator);//专业快速RC振荡器

110 = FOSC/64;

101 = FOSC/16;

100 = FOSC/4;

011 = FRC(clock supplied from a dadicated FRC Oscillator);//专业快速RC振荡器

010 = FOSC/32;

001 = FOSC/8;

000 = FOSC/2;

bit3 Unimplemented:Read as ’0‘;

bit2 ADNREF : ADC Negative Voltage Reference Configuration bit:(ADC 负项参考电压配置)

1 = Vref- is connected to external Vref- pin;

0 = Vref- is connected to Vss;

bit1-0 ADPREF<1:0>:ADC Positive Voltage Reference Configuration bit:

11 = Vref is connected internally to FVR buffer 1;

10 = Reserved;

01=Vref is connected to Vref pin;

00 = Vref is connected to VDD;

ADCON0:ADC Control REGISTER 0 0x09D

R/W-0/0 R/W-0/0 R/W-0/0 R/W-0/0 U-0 R/W-0/0 R/W-0/0 R/W-0/0
ADRMDCHS<4:0>GO/nDONEADON
bit7 bit0
说明:

R=Readable bit, W=Writable bit, U=Unimplemented bit,read as "0",

u=Bit is unchanged, x=Bit is unknown, -n/n=Value at POR and BOR/value at all other resets,

'1'=Bit is set, '0=Bit is cleaed.

bit7 ADRMD :ADC Result Mode Bit(ADC 结果模式)

1 = ADRESL and ADRESH provide data formatted for a 10-bit result;

0 = ADRESL and ADRESH provide data formatted for a 12-bit result;

bit6-2 CHS<6:2>:PositiveDifferential Input Channel Select Bits;(正的差分输入通道选择)

11111 = FVR(Fixed Voltage Reference) Buffer 1 Output;

11110 = DAC_Output;

。。。

01110 = Reserved,No Channel connected;

01101 = AN13;

01100 = AN12;

01011 = AN11;

01010 = AN10;

01001 = AN9;

01000 = AN8;

。。。

00100 = AN4;

00011 = AN3;

00010 = AN2;

00001 = AN1;

00000 = AN0;

bit1 GO/nDONE : ADC Conversion status bit;

1 = ADC Conversion cycle in progress,Setting this bit starts an ADC conversion cysle

.this bit is automatically cleared by hardware when the ADC conversion

has completed;

0 = ADC conversion completed;

bit0 ADON:ADC Enable bit;

1 = ADC is enabled;

0 = ADC is disabled;

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

ADCON1 = 0b10010000;

该语句设置ADC Control Register 1,即AD 变换控制寄存器1。

ADFM=1:ADC输出格式位2进制补码;

ADCS<2:0>=0b001:ADC变换时钟为FOSC/8;

ADNREF=0:Vss为参考电压;

ADPREF<1:0>=0b00:ADC正向参考电压为VDD

ADCON0 = 0b00000001;

ADRMD = 0:ADC结果为12位;

CHS<6:2>=0b00000:正向差分输入通道位AN0;

GO/nDONE=0:ADC变换完成;

ADON = 1:ADC is enabled。

AD Conversion 步骤:以AIN0为例:

1、端口配置

TRISAbits.TRISA0 = 1;//input

ANSELAbits.ANSA0 = 1;//INPUT

2、配置ADC模块

ADCON1bits.ADCS

//VREF- is connected to Vss

ADCON1bits.ADNREF = 0;

//VREF is connected to VDD

ADCON1bits.ADPREF = 0b00;

3、配置ADC interrupt(可选)

4、延时

5、开始变换,ADGO=1

6、两种等待变换结束:

7、读取ADC转换结果

8、清除ADIF

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