Parallel

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Parallel Interface



The parallel interface is used exclusively for graphics display and provides the fastest available communication method when operating in full hardware mode. When possible, displays with a 16-bit parallel interface are recommended for maximum performance.


In practice, however, not all microcontrollers have a free 16-bit port—or two available 8-bit ports. To accommodate this, the parallel interface can be configured in one of the following modes:


Hardware Mode

The data bus is implemented as a full 16-bit port on 16-bit MCUs, or as two 8-bit ports on 8-bit MCUs.


Mixed Mode

One byte (upper or lower) of the 16-bit data bus uses a full 8-bit hardware port or half 16-bit port (upper or lower), while the remaining 8 bits are assigned to individually configurable GPIO pins.


Software Mode

All 16 data bits are assigned to individually configurable GPIO pins. This mode is significantly slower than the hardware-based options and should be used only when no hardware ports are available.





Parallel Interface Signal Lines:

    • CS - Output - TFT chip select.
    • RS/DC - Output - Data/command control, indicating the type of data currently being transmitted.
    • WR - Output - Write strobe for display data.
    • RD - Output - Read strobe for display data.
    • RESET - Output - Hardware reset for the graphics display controller.
    • DB0–DB15 - Output - 16-bit data bus. For 8-bit commands, only the lower byte is used; for graphical data, both bytes are used. 

 


Additional Power and Control Lines (Non-SPI):

    • BL - Output - Digital control for the backlight LED. PWM can be used for brightness control. If the backlight is always on, connect to 3.3 V VCC through a pull-up resistor.
    • VCC - Power - Connect to a 3.7–5 V supply if the TFT module includes an onboard 3.3 V LDO or regulator; otherwise, connect directly to a 3.3 V supply. Some modules provide a bypass resistor for direct PCB VCC connection. Because TFT displays may draw significant current, using the onboard regulator is recommended when available.
    • GND - Power - Ground connection.
    • LED - Power - Backlight LED power. A current-limiting resistor may be required.


Optional Peripheral and Auxiliary Lines:

    • T_DIN/MOSI - Touch data input/SPI Master Out, Slave In
    • T_DO/MISO - Touch data output/SPI Master In, Slave Out
    • T_CLK/SCLK - Touch serial clock/SPI serial clock
    • T_CS - Touch chip select
    • T_IRQ/PEN - Touch interrupt request (microcontroller input, active on touch)
    • SD_CS - Output - Chip select for the SD card via SPI, if supported. Not all TFT modules include an SD card slot.
    • F_CS - Output - Chip select for the external flash memory via SPI. Some TFT modules provide flash memory pads without a populated IC, allowing a compatible device to be added manually.







 

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