Pic single-chip multi-channel ad switching program introduction

The PIC microcontroller is an integrated circuit (IC) used to develop and control peripheral devices. A CPU with decentralized (multitasking) capabilities. Compared with humans, the brain is the CPU, and the part shared by PIC is equivalent to the human nervous system. The PIC microcontroller is a small computer. PIC microcontrollers have computational functions and memory memory like CPU and are controlled by software. However, processing power is generally limited, and memory capacity is limited, depending on the type of PIC. However, their maximum operating frequency is about 20MHz, and the memory capacity is about 1K-4K bytes for writing programs. The clock frequency is related to the time of the scanner and the time the program instructions are executed. However, the program processing capability cannot be judged only by the clock frequency, and it also changes with the architecture of the processing device. If it is the same architecture, the processing power of the clock frequency will be stronger.

Understanding of AD conversion

The so-called analog quantity is well understood. The analog quantity refers to the quantity that the variable changes continuously within a certain range; that is, it can take any value (within the value range) within a certain range (defined domain). The digital quantity is a discrete quantity, not a continuous change quantity. It can only take a few discrete values. For example, a three-digit numeric variable can only take seven integer values ​​of 0.1.2.3.4.5.6.7.

Instead of passing through the AD channel, after passing through the ordinary IO port, the analog signal will only have two digital results on the pin, one is 1 and the other is 0, and the analog value cannot be accurately described. The quantity signal is a variable signal. If the signal is 0V--10V, or 50MA to 100MA, the switching signal is an on-off signal, such as a light switch at home, the digital signal is a continuous switching signal or a high-low level signal. For example, 1101----high, low, high. A series of signals represent digital signals.

Pic single-chip multi-channel ad switching program introduction

Let's continue to talk about the AD accuracy problem. If the 8-bit AD precision is used, the full voltage value is divided into 2^8=256 copies. For example, the voltage range collected by 51 MCU is 0-5v, then 0v corresponds to 0 5v. 255.

Pic single-chip multi-channel ad switching program

Void ad_init (void)

{ ADIF=0X00;

ADCON1=0x80;//

ADCON0=0X81; //The ten-digit result must be 8 bits high

TRISA=0X0FF; / / default is AD input

PORTA=0X00;

TRISE0=1;

TRISE1=1;

TRISE2=1;

ADON=1;

}

Void delay(unsigned int x)

{

Unsigned int a,b;

a=(2*x/8);

For(a;a)0;a--);

For(b=5;b》0;b--);

}

Unsigned int read_ADresult(unsigned char channel)

{

Channel &= 0x07; // The syntax here is equivalent to channel=channel&0x07.

ADCON0 &= 0x85; // Clear current channel

ADCON0 |= (channel "3"; //10 xxx 001

Delay(30);

ADGO=1;

While(ADGO) conTInue;

Return (ADRESH "8) + (ADRESL);

// return ADRESL;

}

Unsigned int ad_res[8];//Store AD conversion value

For(j=0;j"8;j++)

{

Ad_res[j]=read_ADresult(j);

}

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