CAN Bus Based Automatic Water-Level Gate Control System

Overview

The CAN Bus Based Automatic Water-Level Gate Control System is a distributed embedded system developed using three LPC2129 ARM7 microcontroller nodes.

The system automatically senses the water level, communicates the measured value through a CAN bus, displays the corresponding level and status, and controls a gate using a servo motor.

Objective

To design and implement a distributed embedded system using three LPC2129 microcontroller nodes communicating over a CAN bus to automatically sense the water level, display the corresponding status, and control a gate through a servo motor without manual intervention.

System Architecture

The system consists of three independent LPC2129 nodes connected through a shared CAN bus.

Node 1 - Sensing Node

• Uses an MCP3204 12-bit SPI ADC.
• A potentiometer is used as the water-level sensor stand-in.
• Reads the analog input through SPI.
• Transmits the raw ADC value through CAN2.

Node 2 - Display Node

• Receives the ADC value through CAN.
• Classifies the value into Level 1, Level 2, or Level 3.
• Displays the water-level and gate status on a 16x2 LCD.
• Indicates the current level using three LEDs.

Node 3 - Actuation Node

• Receives the same CAN data independently.
• Determines the corresponding water-level.
• Controls a servo motor according to the detected level.

Working Principle

1. The potentiometer provides a variable analog signal representing the water level.
2. MCP3204 converts the analog signal into a 12-bit digital value.
3. Node 1 reads the ADC value through SPI.
4. Node 1 transmits the value through CAN2.
5. Node 2 and Node 3 receive the CAN data independently.
6. Node 2 displays the level and gate status on the LCD and indicates the level using LEDs.
7. Node 3 controls the servo motor according to the detected level.

The ADC produces values from 0 to 4095.

Level Control

Level	Status	Servo Position
Level 1	Low level / Gate Closed	0°
Level 2	Medium level	90°
Level 3	High level / Gate Fully Open	180°

Block Diagram

                 Water-Level Input
                  Potentiometer
                        |
                        v
                +---------------+
                |   MCP3204     |
                |   12-bit ADC  |
                +-------+-------+
                        |
                       SPI
                        |
                        v
                +---------------+
                |    NODE 1     |
                |    LPC2129    |
                | CAN Transmitter|
                +-------+-------+
                        |
                    CAN BUS
                  CAN-H / CAN-L
                   /         \
                  /           \
                 v             v
        +---------------+  +---------------+
        |    NODE 2     |  |    NODE 3     |
        |    LPC2129    |  |    LPC2129    |
        | CAN Receiver  |  | CAN Receiver  |
        +-------+-------+  +-------+-------+
                |                 |
             LCD + LEDs        Servo Motor
                                  |
                                  v
                              Gate Control

Hardware Components

• LPC2129 ARM7 Microcontroller - 3 boards
• MCP3204 12-bit SPI ADC
• Potentiometer
• 16x2 LCD
• LED Indicators - 3
• Servo Motor
• CAN Transceivers
• 120Ω CAN Termination
• Regulated Power Supplies

Software Components

• Embedded C
• Keil µVision IDE
• Flash Magic / ISP Utility
• Proteus 8 Professional
• SPI
• CAN2
• PWM
• GPIO

Communication

SPI

SPI is used for communication between Node 1 and the MCP3204 ADC.

CAN

CAN is used for communication between the three LPC2129 nodes. Node 1 broadcasts the ADC reading, while Node 2 and Node 3 independently receive and process the same data.

ADC Conversion

MCP3204 is a 12-bit ADC with an output range of 0 to 4095.

For a 3.3 V reference:

Voltage = ADC Value × 3.3 / 4096

Project Features

• Automatic water-level monitoring
• CAN-based multi-node communication
• 12-bit ADC measurement
• SPI-based ADC interfacing
• LCD status display
• Three-level LED indication
• Servo-based gate control
• Distributed embedded architecture
• Expandable CAN network

Advantages

• Reduces manual intervention
• Provides automatic gate control
• Supports reliable multi-node communication
• Separates sensing, display, and actuation functions
• Easy to extend by adding additional CAN nodes
• Provides real-time level indication

Applications

• Water reservoir management
• Irrigation canal gate control
• Check dam control
• Water storage tank monitoring
• Flood-control gate systems
• Industrial water-level monitoring
• CAN-based distributed automation

Future Scope

• Replace the potentiometer with a calibrated ultrasonic or pressure-based water-level sensor.
• Add GSM or IoT connectivity for remote monitoring and alerts.
• Add data logging for water-level history.
• Implement interrupt-driven CAN reception.
• Add gate-position feedback for closed-loop control.
• Extend the system to control multiple gates using additional CAN nodes.