PIC12 ADC Converter using PIC12C671 with Proteus Simulation

Introduction

The PIC12 ADC Converter project demonstrates how the built-in analog-to-digital converter (ADC) of the PIC12C671 microcontroller works in a practical setup.
An analog input signal is repeatedly sampled, converted into digital form, and then sent out serially for visual representation.
This project is ideal for learning ADC fundamentals using a microcontroller project simulated in Proteus simulation.
It clearly shows how reference voltage selection affects conversion results.
The design is compact, educational, and well-suited for embedded systems and DIY electronics learning.

How the Project Works (Overview)

The PIC12C671 samples an analog voltage applied to its input pin and converts it into an 8-bit digital value using its internal ADC.
The converted result is then shifted out bit-by-bit through GPIO pins and displayed externally using a latch and 7-segment displays.
The ADC can operate with either VDD or an external VREF, selectable during runtime using a control signal.
All signal activity and conversion behavior are visible in Proteus through transient analysis graphs.

Block Diagram / Workflow Explanation

1. Analog Input Signal is applied to the ADC input pin

2. ADC Module (PIC12C671) samples and converts the signal

3. Reference Voltage Selection switches between VDD and external VREF

4. ADC Result Register (ADRES) stores the conversion value

5. Serial Output Logic shifts data bit-by-bit via GPIO

6. External Latch & Displays show the converted value

7. Proteus Graph visualizes voltage and conversion results

Key Features

• Uses internal ADC of PIC12C671 microcontroller

• Runtime selection of voltage reference (VDD or external VREF)

• Serial output of ADC result without dedicated UART

• Interrupt-driven ADC completion handling

• Visual display using 7-segment outputs

• Fully simulated using Proteus VSM

Components Used

• PIC12C671 microcontroller

• External voltage reference source

• Serial latch IC

• Dual 7-segment displays

• Clock and sample control signals

• Proteus VSM environment

Applications

• Learning ADC working principle in microcontrollers

• Embedded systems education and training

• Sensor interfacing experiments

• Low-pin-count microcontroller projects

• ADC reference voltage comparison studies

• Firmware testing using Proteus simulation

Explanation of Code (High-Level)

The firmware initializes the ADC module and GPIO configuration.
An external interrupt wakes the MCU from sleep to begin sampling.
The ADC reference source is selected dynamically based on input state.
After acquisition delay, conversion starts and completion triggers an interrupt.
The ADC result is read from ADRES and serialized bit-by-bit using GPIO pins.
Clock pulses are generated manually to shift data to the external display logic.

Source Code

Download

       LIST    p=12C671 ; 
	#include "P12C671.INC" ; Include header file

; Macro to generate a MOVLW instruction that also causes a model break:
break   MACRO arg
        DW    0x3100 | (arg & H'FF')
        ENDM

bank0   MACRO 
	bcf STATUS,RP0
	ENDM
	
bank1   MACRO
	bsf STATUS,RP0
	ENDM	

⬇ Download file

Complete Source Code

Proteus Simulation

In Proteus, the analog input ramps smoothly while ADC sampling occurs periodically.
The converted digital values update in real time and appear on the 7-segment displays.
Switching the reference voltage clearly changes the conversion scale.
The transient graph shows ADC response aligned with input voltage changes.

Complete File

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PIC12 ADC Converter using PIC12C671 with Proteus Simulation