LCD controller and Driver

This time I'll talk about how the control flow from the MCU to the LCD is how our bitmap data is displayed on the LCD. Before we learned that the LCD display is implemented by dynamic scanning, each time a full line is displayed, each line in a frame is scanned once, so that there is a circuit to control the output voltage on the row and column, this circuit is the LCD driver, and the output of the driver and the image and the LCD is related to the mode of operation, The driver needs to accept the control signal from the image conversion, thus changing the output voltage on the row/column, the circuit that converts the working mode and image bitmap into the control signal is the controller. The controller receives the bitmap data from the MCU and converts it into a control signal to the driver. For small-resolution LCDs, drivers and controllers are usually directly integrated into an IC, while large-size LCDs, drivers and controllers are separate, and generally the drive and row drivers are separate. So what exactly is the connection between the controller and the drive? Let's take a look at:

The relevant pictures of this topic are as follows:

YD is a frame synchronization signal, LP is a line synchronization signal, data is a column-driven bus to transmit the output data on the column (0 or 1), the XCLK is a shift clock, each time the data is transmitted once per jump, doff# is the output signal off. In the case of 640x480 monochrome screens, 640 columns output, 640 bits of output, 80 bytes, that is, each row of scans, the data required on the column is 80 bytes. Assuming that the column drive uses a 8-bit data cable, 80 bytes requires 80 xclk clocks. These signals, all driven by the controller, still in 640x480 monochrome display as an example, the drive is a 8-bit bus, each frame starts with the controller continuously output 80 XCLK, and the first row of data output, the column controller at each XCLK when the data is latched, and then the controller on the YD output a pulse, row driver complex bit, ready to output from the first line, the controller outputs a pulse on the LP, the column drive resets, the data output just latched, and the row drive is output from the first line, then the first line is displayed, then the controller outputs the second line of data, then the output of a LP, then the second line is displayed, and so on, until the first 480 lines and then output a YD back to the first line, that is, the start of the second frame of the scan. Thus, the output of the drive is determined entirely by the timing and data of the controller. For the controller and drive separation system, the drive is not aware of the current display characteristics, such as monochrome or grayscale or color, color depth is how much, so on such a system, gray/color can only be implemented in FRC way, so generally separate universal controller, the operating frequency is quite high. Reach dozens of trillion, for a large size like a computer display, even up to hundreds of trillion.

LCD controller and Driver