Recently, I like to play "Need for Speed", so I bought a game steering wheel.
After the courier arrival, I can't wait to open it. I have played for a while. I wanted to throw it away. I feel a little bad. I don't have a point in my hand. I don't want to play a little more suddenly like a swivel direction. It is better to be cool than the keyboard. Throwing the trash cartridge is a bit unfortunately, thinking about it, I feel that I can spend some thought to transform, build a good game controller.
At home, you can talk to "speed and passion", just 1st floor has already abandoned 10 years of simple treadmill, and a very broken bicycle sent by a neighbor.
I chose a bicycle. I personally feel that the rear round frame of the bike is actually natural. There is another reason, I move the treadmill.
The basic design is as follows:
Bicycle head ----. 1882. Racing steering wheel
Bicycle pedal ----. 1882. Racing throttle
Bicycle left brake ----. 1882. Racing feet
Bicycle right brake ----. 1882. Racing handbrake or nitrogen acceleration
2, design ideas
The general game steering wheel is installed on the steering wheel and the throttle brake. When the player hits the steering wheel or the throttle brake, the value of the potentiometer changes, and the voltage of the resistor is applied to the resistor, thus knowing the steering wheel. Or change in the throttle brake, and communicate with the computer via the MCU or USB chip.
Since I don't quite understand the knowledge of USB communication, I will use "brought-in-the-way" and obtain the main board of the steering wheel.
Simply, as long as you enter a corresponding resistor to the main board of the steering wheel, you can "deceive" it work, send the corresponding data to the host computer (computer "Need for Speed"), and what we have to do is to use some sensors. To measure some parameters of the bicycle (speed, head steering, whether to brake), after the MCU is processed, the digital potentiometer is changed, and it is access to the main circuit board of the steering wheel.
Please see the details:
3, tool
One bicycle, a bicycle cycle.
Hall sensor module, micro switch, LPC2013 minimum system module, electronic compass module, acceleration sensor module
ULINK debugger, one computer, MDK Keil4 development environment, multimeter
Essential tools for playing electronics: electric iron, tin wire, absorbers, screw pen, tweezers, waterproof tape, table drill, tie, etc., anyway, the welding circuit board should have, no fine detailed NS.
4, steering wheel disassembly
Unpack the steering wheel and measure some parameters:
The maximum resistance value of the directional disc linear potentiometer, the winding direction of the steering wheel is exhausted, and the resistance of the direction in the direction.
The resistance of the brake is not stepped on, and the resistance of the brake is turned on.
The resistance when the throttle is not stepped on, and the resistance of the throttle is turned on.
A linear potentiometer is shared by measurement finding, braking and throttle.
For the steering wheel, when the steering wheel is hiented, the potentiometer resistance is just half the maximum resistance value. In this way, there is no need to pay too much attention to its resistance value.
Even so, the selected potentiometer does not exceed one order level.
5, circuit design and welding
1. Since the ARM7 2103 module that is bought is already the smallest system, all pins are directly drawn, so it only needs to be slightly extended by the feet plate, which is convenient to install. The pins used through the entire MCU module have - SPI0 pin, I2C0 pin, 2 external interrupts, some GPIO ports indicate LED, touch switch (no available), UART0 pin (debug output data, There is no), etc.
The circuit diagram does not need to be given, if you basically understand or have learned ARM, then you know how to pick up, I just painted a sketch, start welding, the welded plate is as follows.
2. Take out the main board and transfer plates of the steering wheel, weld to a multi-purpose panel, weld the terminal, which is convenient to install.
In order to facilitate installation, I also give two Hall sensors and acceleration sensors, and the electronic compass welded several boards, coupled with the wiring. Family blessing.
6, module detailed introduction
1. Hall sensor (measurement of bicycle)
The Hall sensor module works like this, 3 pin, VCC foot, GND feet, DATA feet, default status DATA foot output low, if there is magnet, generate magnetic field cut, will output a high level, When the magnet is away from the sensor and restores the low level.
So put a magnet on the foot of the bicycle, put the two Hall sensor modules to the two positions passing through the pedal, when stepping on the bicycle, by calculating the time difference between the two Hall sensors, to obtain a rider step on The speed of bicycle, thereby corresponds to the depth of the racing throttle.
2. Electronic compass, acceleration sensor module (measurement of bicycle corners)
The chip model I use is HMC5883L, I2C interface, 75Hz data reading frequency, not too much, power-on reset, set the work parameters and working mode through the I2C interface, you can read data. . The pattern of data is the component of the geomagnetic XYZ axis, but also don't understand. The benchmark of the XYZ axis is related to the location of the chip. However, the detail data can be calculated according to the chip manual, and the angle between the geomagnetic can be measured.
There is also an ADXL345 acceleration sensor on the module, which is the I2C interface, mainly because the bicycle's head rotation plane is not completely horizontal, because the bicycle's head shaft (I don't know if it is said to be called), there is a angle of the ground plane, so The entire module cannot operate in the horizontal plane, that is, the plane of the XY axis of the electronic compass, is not parallel to the horizontal plane, and the z-axis's geomagnetic component is certainly less than 0, at least most of the time is not 0.
Said that so many ADXL345 acceleration sensors are used to measure horizontal inclination, correct data for electronic compass.
In fact, I also bought a module, which integrates an acceleration sensor and a angular velocity sensor. It was originally afraid that an acceleration sensor had an error, and the average value can be corrected, and it is not used.
In the United States, it is necessary to calibrate because of the use of electronic compass, so every time you start playing, you need to calibrate, because the location of the bicycle has caused the car head to be in the middle of the head, so it needs to be initialized. Even when playing, play too much, the movement is too large, causing the bicycle displacement, but also constantly correct.
The best way, or to install a rotating potentiometer on the car to replace the electronic compass, but considering the installation of the potentiometer requires a suitable gear, it is very troublesome, and there is no mold, so it will be.
3. Small motion switch (brake, nitrogen acceleration)
In the bicycle brakes, the starting scheme is the pressure sensor. In this way, the brake parameters are analog quantity, but the installation problem is too trouble, so the switch is taken.
The micro switch is directly connected to the circuit board of the steering wheel, and does not pass the ARM7 LPC2103 circuit board.
4. Digital potentiometer MCP42050.
Maximum range 50K ohm, SPI communication interface, 2 potentiometers, accuracy is 50k Euro / 256, is already very sufficient. In the initial setting, the throttle depth (ie the speed) is 10 levels, and the steering wheel is set to a level every 5 degrees, and the left and right is 32 levels. More than enough.
5.lpc2103 module.
Nothing to say, handle data.
7, programming, debugging
1. I use a small operating system UCOS to divide 4 tasks.
Task 1: The indicator is off. Task 2: Electronic compass data read, acceleration sensor data read, data processing is performed to get the corner and written in the OR variable. Task 3: The data processing of the Hall sensor, writes the time interval (speed) into the ELC variable. Task 4: Write the corresponding resistance value into the digital potentiometer based on the data of the speed and the two global variables.
Original link: https://www.eeboard.com/news/blie/
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