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PIC12F629IMF 参数 Datasheet PDF下载

PIC12F629IMF图片预览
型号: PIC12F629IMF
PDF下载: 下载PDF文件 查看货源
内容描述: 8引脚基于闪存的8位CMOS微控制器 [8-Pin FLASH-Based 8-Bit CMOS Microcontrollers]
分类和应用: 闪存微控制器
文件页数/大小: 132 页 / 4519 K
品牌: MICROCHIP [ MICROCHIP ]
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PIC12F629/675  
The output of the sample and hold is connected to the  
input of the converter. The converter generates a  
binary result via successive approximation and stores  
the result in a ±0-bit register. The voltage reference  
used in the conversion is software selectable to either  
VDD or a voltage applied by the VREF pin. Figure 7-±  
shows the block diagram of the A/D on the PIC±2F675.  
7.0  
ANALOG-TO-DIGITAL  
CONVERTER (A/D) MODULE  
(PIC12F675 ONLY)  
The analog-to-digital converter (A/D) allows conversion  
of an analog input signal to a ±0-bit binary representa-  
tion of that signal. The PIC±2F675 has four analog  
inputs, multiplexed into one sample and hold circuit.  
FIGURE 7-1:  
A/D BLOCK DIAGRAM  
VDD  
VCFG = 0  
VCFG = 1  
VREF  
GP0/AN0  
GP1/AN1/VREF  
GP2/AN2  
ADC  
10  
GO/DONE  
GP4/AN3  
ADFM  
CHS1:CHS0  
10  
ADON  
ADRESH ADRESL  
VSS  
controls the voltage reference selection. If VCFG is set,  
then the voltage on the VREF pin is the reference;  
otherwise, VDD is the reference.  
7.1  
A/D Configuration and Operation  
There are two registers available to control the  
functionality of the A/D module:  
7.1.4  
CONVERSION CLOCK  
±. ADCON0 (Register 7-±)  
2. ANSEL (Register 7-2)  
The A/D conversion cycle requires ±± TAD. The source  
of the conversion clock is software selectable via the  
ADCS bits (ANSEL<6:4>). There are seven possible  
clock options:  
7.1.1  
ANALOG PORT PINS  
The ANS3:ANS0 bits (ANSEL<3:0>) and the TRISIO  
bits control the operation of the A/D port pins. Set the  
corresponding TRISIO bits to set the pin output driver  
to its high impedance state. Likewise, set the  
corresponding ANS bit to disable the digital input  
buffer.  
• FOSC/2  
• FOSC/4  
• FOSC/8  
• FOSC/±6  
• FOSC/32  
Note: Analog voltages on any pin that is defined  
as a digital input may cause the input  
buffer to conduct excess current.  
• FOSC/64  
• FRC (dedicated internal RC oscillator)  
For correct conversion, the A/D conversion clock  
(±/TAD) must be selected to ensure a minimum TAD of  
±.6 µs. Table 7-± shows a few TAD calculations for  
selected frequencies.  
7.1.2  
CHANNEL SELECTION  
There are four analog channels on the PIC±2F675,  
AN0 through AN3. The CHS±:CHS0 bits  
(ADCON0<3:2>) control which channel is connected to  
the sample and hold circuit.  
7.1.3  
VOLTAGE REFERENCE  
There are two options for the voltage reference to the  
A/D converter: either VDD is used, or an analog voltage  
applied to VREF is used. The VCFG bit (ADCON0<6>)  
2003 Microchip Technology Inc.  
DS41190C-page 41