Inductive touch screen control system hardware and software design - Database & Sql Blog Articles

Photocoupler

The touch screen control circuit is designed to detect and process input signals from a stylus or finger. As shown in Figure 1, when the LCD screen is touched, the touch detection device senses the signal along the X and Y axes. This signal goes through an analog electronic switch, then undergoes two stages of amplification and filtering. After that, the signal is processed in two different ways: one for voltage rectification and the other for frequency detection. The microcontroller HT46RB70 processes the data to determine the touch position and the type of touch. Once identified, the MCU sends the corresponding signal to the computer, enabling touch input functionality.

Throughout the entire process, the timing and coordination of the touch screen control circuit are managed by the single-chip microcomputer. Detailed descriptions of the circuits for each module will be provided in the following sections.

Figure 9: MCU Circuit

5. Software Design

The software design for the inductive touch screen controller includes several key components such as I/O initialization, timer counter setup, touch pen interrupt service routines, communication with the computer, and the main program flow. The interrupt service routine handles both coordinate calculation and frequency detection of the touch signal. When the touch controller receives a touch event, the MCU triggers the interrupt service routine, captures the touch coordinates, and initiates communication with the computer to transmit the touch information, completing the input process effectively.