Microcontrollers are a type of microcontroller that are widely used in everyday life. Because of its comprehensiveness and practicality, involving more knowledge, this course has the ability to develop and train students' hardware and software using SCM technology, students' ability to analyze problems, solve problems, and occupational skills of higher vocational students. The ability to practice innovation has an important role in laying the foundation for automatic control and application of electronic product testing and design. This article comes from the 2011 National Electronic Design Contest title F, designed to achieve windsurfing control system. The system requires a preset angle through the keyboard, uses the wind power of the fan to control the angle of the windsurfing board, and displays it in real time. This question involves the angle detection, motor drive, PWM, closed-loop control, AD conversion and other SCM application technology, is an important part of the sailboard autonomous navigation system. According to requirements, the system consists of a single-chip minimum system, human-computer interaction module, fan control module, angle detection module, sound and light alarm module, and system power supply module. The specific block diagram is shown in Figure 1. Since the present method uses only a single axis and requires a gravity vector, the calculated tilt angle can be accurate only when the device has a specific direction and the x-axis always has a center plane. According to the basic trigonometric principle, the gravity vector projection on the x-axis produces an output acceleration equal to the sine of the angle between the accelerometer x-axis and the horizontal line. The horizontal line is usually a plane perpendicular to the gravity vector. At an ideal gravity of 1 g, the output acceleration is: Air Powered Stirrer,Vertical Air Mixer,Vertical Pneumatic Stirrer,Industrial Pneumatic Air Mixer RUDONG HONGXIN MACHINERY CO.,LTD , https://www.rdhxmfr.com
1.1 Microprocessor Module STC's STC12C5A60S2 microcontroller is used as a microprocessor.
The single-chip microcomputer is an enhanced 51 single-chip microcomputer, featuring high speed, low power consumption, and superior anti-jamming. Internally integrated MAX810 reset circuit, 2-way PWM, 8-channel high-speed 10-bit A/D converter (speed up to 250,000 times/ Seconds), very much in line with system requirements.
1.2 Angle Detection Module The MMA7361 acceleration angle sensor measures the angle. The acceleration angle sensor calculates the tilt angle of the device relative to a plane by measuring the acceleration due to gravity. The angle sensor is responsive, accurate, and affordable. Angle measurement using an acceleration sensor is divided into three types: single-axis inclination measurement, dual-axis inclination measurement, and three-axis inclination measurement. In this design, as long as the angle between the windsurfing board and the vertical direction is measured, single-axis tilt angle measurement is used. The principle of single-axis inclination measurement is shown in Figure 2. A single axis (ie, x-axis) rotates by gravity. 
AX. OUT[g]=lgxsin(φ)
In actual use, consult the technical manual of the sensor MMA7361 used and the principle of using the acceleration sensor to measure the angle, and the relationship between the output voltage and the measurement angle can be obtained as:
Among them, VOUT denotes the output voltage of the acceleration sensor, VOFFSET denotes the offset of the acceleration sensor with a gravitational acceleration of 0 g, represents the sensitivity of the acceleration sensor, 1 g denotes the gravitational acceleration on the earth, and θ denotes the deflection angle.
So, you can get the angle value: 