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Section 22. Basic 8-bit A/D Converter

Tham khảo tài liệu 'section 22. basic 8-bit a/d converter', kỹ thuật - công nghệ, điện - điện tử phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Microchip Section 22. Basic 8-bit A D Converter HIGHLIGHTS This section of the manual contains the following major topics 22 22.1 Introduction.22-2 22.2 Control Registers.22-3 22.3 A D Acquisition Requirements.22-6 22.4 Selecting the A D Conversion Clock.22-8 22.5 Configuring Analog Port Pins.22-10 22.6 A D Conversions.22-11 22.7 A D Operation During Sleep.22-14 22.8 A D Accuracy Error.22-15 22.9 Effects of a RESET.22-16 22.10 Connection Considerations. 22-16 22.11 Transfer Function . 22-16 22.12 Initialization.22-17 22.13 Design Tips.22-18 22.14 Related Application Notes.22-19 22.15 Revision History . 22-20 Basic 8-bit A D Converter Note Please refer to Appendix C.2 or the device Data Sheet to determine which devices use this module. 1997 Microchip Technology Inc. DS31022A page 22-1 PICmicro MID-RANGE MCU FAMILY 22.1 Introduction This Analog-to-Digital A D converter module has four analog inputs. The A D allows conversion of an analog input signal to a corresponding 8-bit digital number. The output of the sample and hold is the input into the converter which generates the result via successive approximation. The analog reference voltage is software selectable to either the device s positive supply voltage Vdd or the voltage level on the AN3 VREF pin. The A D converter has a unique feature of being able to operate while the device is in SLEEP mode. The A D module has three registers. These registers are A D Result Register ADRES A D Control Register0 ADCON0 A D Control Register1 ADCON1 The ADCON0 register shown in Figure 22-1 controls the operation of the A D module. The ADCON1 register shown in Figure 22-2 configures the functions of the port pins. The port pins can be configured as analog inputs or a voltage reference or as digital I O. Figure 22-1 Basic 8-bit A D Block Diagram CHS1 CHS0 AN3 VREF AN2 AN1 AN0 PCFG1 PCFG0 DS31022A-page 22-2 1997 Microchip Technology Inc. Section 22. Basic 8-bit A D Converter 22.2 Control Registers Register 22-1 ADCON0 Register R .