Joystick and STM32

Today in this tutorial, I am going to interface Joystick module with STM32F103 controller. This module can be use for various purposes for eg- controlling a bot, or controlling the camera direction etc. As we know, the module gives analog output so it can be used for feeding the analog input based on direction or movement.

Joystick-Module

CubeMX Setup

As the output from the Joystick pins is analogue, we will use ADC to read these Pins. And also I am going to use 4 LEDs to demonstrate the working. Below is the setup of cube mx

Cubemx_setup_joystick

The ADC setup is shown below. I am using 2 channels i.e. channel 1 and channel 2 of the ADC1 to connect the 2 pins from the Joystick.

ADC_setting-joystick


Some Insight into the CODE

To store the 12 bit ADC values, output from the joystick PINs, I have created an array of 2 variables.

uint32_t VR[2];

As we are going to read Multiple channels of the ADC1, we have to use DMA to do so. In the above code, DMA is being used to read 2 channels of ADC1.

HAL_ADC_Start_DMA(&hadc1, VR, 2);

ADC in STM32 is 12 bit by default, So the input values from the joystick are going to vary between 0 to 4095 (2^12). You can see that in the picture below

ADC output

if ((VR[0]>=2000) && (VR[0]<=3000))
 {
  HAL_GPIO_WritePin(xmin_GPIO_Port, xmin_Pin, GPIO_PIN_RESET);
  HAL_GPIO_WritePin(xplus_GPIO_Port, xplus_Pin, GPIO_PIN_RESET);
 }

 if ((VR[1]>=2000) && (VR[1]<=3000))
 {
  HAL_GPIO_WritePin(ymin_GPIO_Port, ymin_Pin, GPIO_PIN_RESET);
  HAL_GPIO_WritePin(yplus_GPIO_Port, yplus_Pin, GPIO_PIN_RESET);
 }

 if ((VR[0]>=4000))
 {
  HAL_GPIO_WritePin(xmin_GPIO_Port, xmin_Pin, GPIO_PIN_RESET);
  HAL_GPIO_WritePin(xplus_GPIO_Port, xplus_Pin, GPIO_PIN_SET);
 }

 if ((VR[0]<=800))
 {
  HAL_GPIO_WritePin(xmin_GPIO_Port, xmin_Pin, GPIO_PIN_SET);
  HAL_GPIO_WritePin(xplus_GPIO_Port, xplus_Pin, GPIO_PIN_RESET);
 }

 if ((VR[1]>=4000))
 {
  HAL_GPIO_WritePin(ymin_GPIO_Port, ymin_Pin, GPIO_PIN_RESET);
  HAL_GPIO_WritePin(yplus_GPIO_Port, yplus_Pin, GPIO_PIN_SET);
 }

 if ((VR[1]<=800))
 {
  HAL_GPIO_WritePin(ymin_GPIO_Port, ymin_Pin, GPIO_PIN_SET);
  HAL_GPIO_WritePin(yplus_GPIO_Port, yplus_Pin, GPIO_PIN_RESET);
 }
  • The above code is to toggle LEDs based on the orientation of the Joystick.
  • If it is to the extreme left, the VR[0] = 0, and BLUE LED (xmin) will turn on.
  • Similarly, wherever the joystick is moved, corresponding LED turns on. You can check the entire operation in the video below.


Result




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