{"id":16275,"date":"2024-05-27T11:38:11","date_gmt":"2024-05-27T06:08:11","guid":{"rendered":"https:\/\/fastbitlab.com\/?p=16275"},"modified":"2024-05-27T11:48:40","modified_gmt":"2024-05-27T06:18:40","slug":"stm32-ltdc-lcd-tft-lvgl-mcu3-about-touch-screen-controller","status":"publish","type":"post","link":"https:\/\/fastbitlab.com\/blog\/stm32-ltdc-lcd-tft-lvgl-mcu3-about-touch-screen-controller\/","title":{"rendered":"STM32-LTDC, LCD-TFT, LVGL(MCU3) Lecture 64| About touch screen controller"},"content":{"rendered":"
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About touch screen controller<\/strong><\/span><\/h1>\n
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In this article, we will delve into the interfacing of touch screen controllers on three distinct boards: the STM32F429 DISC board, the STM32F746 DISC board, and the STM32F407 DISC-1 board, as well as explore the interfacing of an external RGB display.<\/span><\/p>\n

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STM32F429 DISC board touch functionality<\/b><\/span><\/h2>\n
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Figure 1. STM32F429 DISC board touch functionality<\/span><\/figcaption><\/figure>\n

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The STM32F429 Discovery (DISC) board features a built-in touch screen controller, namely the STMPE811, an integrated circuit (IC) already present on the board. <\/span><\/p>\n

The STMPE811 controller incorporates an analog-to-digital converter (ADC) for processing touch input. <\/span><\/p>\n

The touch panel on the board utilizes a 4-wire resistive touch panel, and its analog signals are seamlessly connected to the STMPE811 controller.<\/span><\/p>\n

When the touch panel is interacted with using a stylus or touch, it induces a resistance change on the touch panel. Consequently, this resistance variation results in corresponding voltage changes along the connected lines. <\/span><\/p>\n

The STMPE811 controller digitizes these analog signals, effectively converting them into a digital format. These digitized values are subsequently transmitted via the I2C interface to the microcontroller. <\/span><\/p>\n

Notably, the microcontroller employs the I2C3 peripheral for this purpose, and the necessary hardware connections are already established on the board, obviating the need for additional configuration.<\/span><\/p>\n

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The STM32F429 DISC board schematic is shown in Figure 2. <\/span><\/p>\n

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Figure 2.STM32F429 DISC board Schematics<\/span><\/figcaption><\/figure>\n

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The schematic illustrates the connections between the touchscreen controller (STMPE811QTR) and the microcontroller. Key signals, including I2C3_SCL, I2C3_SDA, and TP_INT1, are conveyed from the STMPE811QTR controller to the microcontroller. <\/span><\/p>\n

There is also one more line: touch panel interrupt(TP_INT1), which indicates touch panel activity by being asserted or de-asserted when the touch panel is touched.<\/span><\/p>\n

Please refer to its datasheet for more comprehensive information about the STMPE811QTR IC and its functionalities. This detailed document will provide a deeper understanding of the IC’s capabilities and usage.<\/span><\/p>\n

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STM32F746 disc board touch functionality<\/b><\/span><\/h2>\n
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Figure 3. STM32F746 disc board<\/span><\/figcaption><\/figure>\n

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On this board, there is a capacitive touch panel, and there is a capacitive touch panel controller. <\/span><\/p>\n

FT5336GQQ is a chipset name. The FT5336GQQ chipset serves as the controller for the capacitive touch panel. It manages touch input processing and communication with the microcontroller.<\/span><\/p>\n

This is also I2C-based communication, and the I2C3 peripheral is being used. <\/span><\/p>\n

I2C Communication:<\/b><\/span><\/h3>\n