TE Signal of TFT Display Module

The background of TFT display module

TFT displays with MCU interface generally have an interface with the "TE" signal. The TE signal is an output interface that can provide normal display even without being connected to the MCU.

The TE (Tearing Effect Signal) is a feedback signal from the TFT controller to the MCU. Its function is similar to the FLM (First Line Marker) signal of the past liquid crystal module of monochrome style.

The TE signal is sent from the TFT controller to tell the MCU that it is "starting" to read RAM from the first line and display it. The goal is to avoid conflicts caused by the TFT controller reading RAM data while the MCU is writing data to the same location, which often results in a garbled display.

The application of TFT display module

Situation 1:

For high-speed MCUs with a frame rate of about 1/60 second, the MCU updates the display content of the entire frame faster than the display controller scans (reads) a frame. When the MCU sees the T signal, it starts updating (writing) the display content, and the relevant updates will not conflict with the display controller scanning (reading) RAM. Therefore, there will be no garbled display due to RAM read-write conflicts.

Note that the relevant update (writing) action starts just after the display controller scanning (reading) has just completed.

Situation 2:

For slower MCUs with a frame rate of about 1/60 second, the MCU updates the display content of the entire frame slower than the display controller scans (reads) a frame. When the MCU sees the TE signal, it starts updating the display content. As long as the MCU's updating speed does not exceed two frame times, it will not conflict with the display controller scanning (reading) RAM. Therefore, there will be no garbled display due to RAM read-write conflicts.

Note that the relevant update (writing) action starts just after the display controller scanning (reading) has just begun.

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