MCU capacitive touch sensing technology principle detail

     MCU capacitive touch sensing technology is a common touch screen technology, widely used in smart phones, tablet computers, electronic game equipment and other electronic products. It detects and locates the touch operation by sensing the charge change on the touched object. The principle of MCU capacitive touch sensing technology is described in detail below.

     MCU capacitive touch sensing technology mainly consists of two parts: sensing circuit and control circuit. The sensing circuit is responsible for sensing the charge change on the object being touched, while the control circuit is responsible for converting the sensed charge change into a specific touch operation.

     The inductive circuit usually consists of a set of capacitive sensors, which are usually arranged on the edge of the touch screen. Each capacitive sensor consists of a capacitive electrode and a reference electrode separated by an insulating layer. When the touch screen is touched, the human body or other conductive objects will bring a certain charge, resulting in a change in the capacitance value between the capacitor electrode and the reference electrode. This change in capacitance value can be detected by measuring the voltage between the capacitor electrode and the reference electrode.

     The control circuit is responsible for converting the induced capacitance value change into a digital signal and processing it to achieve the detection and positioning of the touch operation. The control circuit usually consists of a microcontroller unit (MCU) and some peripheral circuits. The MCU is the core part that controls the entire touch screen, it can read the voltage value of the capacitor sensor, and through a series of algorithms and processing to determine whether the touch operation has occurred, and where the touch has occurred.

     Specifically, the control circuit first samples the capacitive sensor, that is, periodically measures the voltage between the capacitive electrode and the reference electrode. The MCU then calculates the corresponding capacitance value based on the sampled voltage value and compares it with the previous capacitance value. If the capacitance value exceeds a certain threshold, it is judged that a touch operation has occurred.

     After determining that the touch operation has occurred, the control circuit also needs to determine the position of the touch. This is usually done by dividing the touch screen into several areas. Each area corresponds to a capacitance sensor, and the MCU will determine the specific location of the touch based on the change in the capacitance value.

     Finally, the control circuit transmits the result of the touch operation through the interface to the host device, such as a smartphone or tablet, to achieve the corresponding function.

     In summary, MCU capacitive touch sensing technology realizes the detection and positioning of touch operations by sensing the charge change on the touched object. It uses a capacitance sensor to sense the change of capacitance value, converts it into a digital signal through a control circuit, and processes it to realize the detection and positioning of touch operation. This technology has the advantages of high sensitivity, fast response speed and strong reliability, so it is widely used in various electronic products.