Development and design of coffee machine control board

At present, coffee has become one of the three major beverages in the world, and coffee pots have gradually become one of the common electrical appliances used in our families. There are three main types of coffee pots on the market: siphon coffee pots, drip coffee pots and pump coffee pots. At present, various electrical appliance manufacturers have conducted research on coffee pots. For example, Panasonic invented a pump-type coffee pot, which can disperse coffee powder through gravity. Some domestic scholars have also designed a coffee pot that can achieve accurate temperature control.

However, currently existing coffee machines generally have disadvantages such as high cost and single function, which undoubtedly affects the use of users and the market of coffee machines. Therefore, we have designed a fully automatic multifunctional coffee machine system, which can realize the following functions: ①Temperature control function: After heating to a certain temperature, the heating system will automatically enter the heat preservation mode. ②Volume control function: the water outlet system can automatically control the water output, and the water will be cut off automatically when the specified water output is reached. ③Concentration control function: Through the mechanical device, the amount of coffee powder can be controlled, which can be connected with the flow control function to complete the concentration control function.

1. Coffee machine system design

The overall structure of the coffee machine in this system mainly includes: water tank, heating device, feeding device, water pump, funnel and filter screen, temperature sensor, pressure sensor, solenoid valve, key panel, etc. Wherein the water tank is used for storing water, the heating device is used for heating water, the feeding mechanism is used for storing and delivering coffee material, and the solenoid valve is used for controlling the amount of coffee.

When it is detected that the water pressure in the water tank is insufficient, the water is sent to the heating place through the water pump, heated by the heating wire at the bottom, and the temperature sensor detects in real time. When the amount and concentration of coffee is detected through the keyboard, the solenoid valve is opened to send the boiling water to the water delivery pipe, and the coffee is evenly sprinkled on the filter containing the coffee powder through the distribution plate, and the coffee can be obtained. The feeding device consists of three parts: a funnel for putting coffee in, a turntable for storing coffee, and a motor to drive it to rotate. Among them, the turntable for storing coffee is divided into several compartments. When the motor drives it to rotate, the coffee powder falls into the filter due to gravity, and the amount of coffee powder is controlled by the rotation of the motor.

2. The main module design of the coffee machine

In the whole system, the main realized functions include: temperature control, concentration control, and water output control. The signals that need to be detected include: the pressure signal of the water tank, the water temperature signal, and the buttons used for human-computer interaction; the equipment that needs to be controlled includes: the water pump from the water supply to the water tank, the relay that controls the heating of the heating wire, the solenoid valve that controls the hot water on and off, and A motor that controls the amount of coffee.

2.1 Main control chip

The microcontroller controller is mainly used for timing and generating relay control signals. AT89C51 microcontroller is a high-efficiency microcontroller with low voltage and high performance, which provides a flexible and cheap solution for many embedded control systems.

2.2 Temperature control module

The temperature control module is mainly used for the heating device. The temperature control module can measure the temperature in real time and display it on the display screen, which is convenient for the user to understand the heating situation. After the heating wire is energized, the water in the heating pot is heated, and the temperature sensor measures the water temperature in real time and displays it on the display. After reaching the temperature for brewing coffee, the microcontroller controls the heating belt to cut off the power.

DS18B20 is a commonly used temperature sensor with small size and strong anti-interference ability. Its use range is from -55°C to +125°C. The error of solid-state temperature measurement is 0.5°C. The working voltage is 3.0-5.5V/DC and does not require any peripheral element.

2.3 Flow Control Module

The flow control module is mainly used for the water outlet module. The main working principle is: the pressure sensor is placed at the bottom of the heating device, and the water volume in the heating device can be monitored in real time by measuring the pressure difference. The water outlet of the coffee machine is controlled by the solenoid valve. Finally, closing the solenoid valve can stop the water. The electromagnetic valve is opened and closed by the signal transmitted by the pressure sensor, which can control the weight of the hot water flowing out. Thereby, the function of controlling the flow is completed, and when the water level is lower than the set value, water is fed through the water pump.

The pressure sensor is HX711, the parameters can directly output the voltage signal, it is installed at the bottom of the heating chamber, it can mainly measure the water volume in the heating chamber in real time, and display the water level in real time.

2.4 Concentration control module

The feeding mechanism of the fully automatic coffee machine is designed as a divided disc, above which is a storage funnel, and a small hole for powder leakage at the bottom, and a motor is connected in the middle of the disc; the inside of the divided disc is divided into 12 equivalent Fan-shaped, wherein the volume of each fan-shaped is about the volume of half a bag of coffee powder. This structure uses gravity to control the coffee powder, and the motor drives the box to rotate, and the coffee powder will leak out from the small hole at the bottom. Rotating a fan-shaped volume can leak out the amount of coffee powder required for half a cup of coffee, and the function of controlling the concentration is completed under the adjustment of the amount of hot water.

3. Debugging of coffee machine

After conception, design and realization, the hardware of the coffee machine is assembled, combined with continuous debugging of the software, the prototype is now able to realize the expected functions. (1) Control the temperature. Press the heating button on the single-chip microcomputer, and the heating wire will be connected to the working voltage to heat the water in the heating pot. It can control the temperature at the desired temperature. After the required temperature, the microcontroller will de-energize the relay of the temperature control module, thus stopping the heating. (2) Control flow. Press the water outlet button on the single-chip microcomputer, the solenoid valve is energized to open the channel, and hot water flows out. After the specified amount of hot water flows out, the single-chip microcomputer will cut off the power of the relay of the quantity control module, thereby stopping the water output. (3) Control the concentration. Through the completed grid structure, after the coffee powder is loaded, the coffee powder leaks from the bottom through the disc, and is brewed with a certain amount of hot water, thereby completing the control of the concentration.

Summarize

This system designs the mechanical structure and control system of the three modules of temperature control, volume control and concentration control of the fully automatic coffee machine, as well as auxiliary alarm, display and other functions. Through the real-time detection of pressure and temperature by the single-chip microcomputer, and the use of keyboards for human-computer interaction, the on-off control of relays, solenoid valves, and water pumps, on the basis of continuous debugging, the three functions of temperature control, flow control, and concentration control can be realized. achieve the desired goal.

The above is an example of the design and development of a fully automatic coffee machine based on a single-chip microcomputer introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. If you have coffee machine solution development needs, you can trust us. We represent a variety of single-chip microcomputers, voice chips, dual-mode Bluetooth ICs, and wifi chips. Brands include Songhan MCU, Yingguang MCU, Jerry Bluetooth, Ankai Bluetooth, Allwinner, and Realtek. Our technical services include: PCB design, MCU development, Bluetooth solution, software and hardware custom development, APP development, small program development, WeChat official account development, etc. It can also undertake the design of intelligent electronic products, the development of living appliances, the research and development of beauty equipment, the application of Internet of things platform, the smart home control system, the development of TWS earphones, Bluetooth earphone speakers, the development of children's educational toys, the design of electronic education products, etc.