Abstract: This paper describes a system for obtaining liquid level by measuring the signal frequency of a sensor. The system comprises a microcontroller-based data processing module, an A/D data input module, a RS-485 communication module, and a liquid level control and alarm module. The liquid level is set via a keyboard, and the host machine can display and set the liquid level of the slave machine. The current liquid level is then transmitted to the controller via a sensor and A/D converter for comparison with the set value. The microcontroller controls a solenoid valve to adjust the liquid level. Finally, actual test results and data analysis are presented.
Keywords: ultrasonic sensor; ICL7135; liquid level control; OCM4X8C
0 Introduction
Currently, there is a lack of long-term reliable application examples in the field of automatic liquid level control in China, and there are no standardized products suitable for liquid level measurement and automatic control. Therefore, it is essential to carry out research on automatic liquid level control.
The system is a water level monitoring and control device. The liquid level in the bottle can be set via a keyboard (any value within 0-25cm), and a solenoid valve (or a similar device) is controlled to bring the liquid level to the set value. An alarm will sound if the liquid level exceeds 25cm or falls below 2cm. The display shows the current liquid level, the weight of the liquid in the bottle, and the valve status in real time.
1. System Function Overview and Block Diagram
This MCS-51 microcontroller, combined with digital chips and analog circuits, performs water level detection and automatic control. The basic workflow is as follows: the host controller sets its own and slave controller's water levels via a keyboard; an ultrasonic sensor measures the voltage value corresponding to the current water level, which is then converted to digital by an ICL7135 and sent to the controller for comparison with the set value; the microcontroller controls the solenoid valve to adjust the host controller's water level and displays the set value and current value on the LCD; the host controller transmits the set value to the slave controller via RS-485 communication; the slave controller can also control the water level like the host controller and display the host's set value and current water level value on the LCD; and it also uses RS-485 communication to transmit the slave controller's current water level back to the host controller for display.
For details, please click: Automatic Water Level Control System Based on Ultrasonic Sensors
