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Waveshare RPi LCD (Rev C)

This screen comes in 3.5" and 4.0" sizes.

6 GPIOs are required to drive the SPI display. One additional GPIO is needed for the XPT2046 touch sensor and one extra GPIO for backlight dimming. Including the VCC and GND pins, a total of 13 connections need to be made to the MCU:

Pin Configuration~

Pin Function ESP32 Pin Config Name Display Pin
1 Module Power 3.3V 3.3V 3.3V
2 Module Power 5v 5V 5V
3 Not connected NC
4 5V
5-10 Not connected NC
11 Touch Interrupt NC TP_IRQ
12 (*) LED Backlight PWM TFT_BCKL LCD_LED
13 Not connected NC
14 Module Ground GND GND
15-16 Not connected NC
17 Module Power 3.3V 3.3V
18 Data Command control pin GPIO4 TFT_DC LCD_RS
19 SPI Master Out Slave In GPIO23 TFT_MOSI LCD/SI/TP_SI
20 Not connected NC
21 Touch Panel Slave Out GPIO19 TFT_MISO TP_SO
22 LCD Reset pin GPIO32 TFT_RST RST
23 SPI Clock GPIO18 TFT_SCLK LCD_SCK/TP_SCK
24 Chip select control pin GPIO15 TFT_CS LCD_CS
25 Module Ground GND GND
26 Touch Chip Select GPIO22 TOUCH_CS TP_CS

SPI MISO, MOSI and SCLK are shared between the touch controller and the LCD controller.

Attention (*)

Only the WaveShare 4.0" RPi LCD Revision C has a solder jumper on the back to enable PWM backlight dimming. Other revisions of this board do not have this feature.

LCD Configuration~

The lcd_config.ini file specifies the different properties of the display, except for the actual pin configuration:

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raspberrypi =
    -D RPI_DISPLAY_TYPE=1
    -D ST7796_DRIVER=1
    -D TFT_WIDTH=320
    -D TFT_HEIGHT=480
    -D TFT_ROTATION=0 ; 0=0, 1=90, 2=180 or 3=270 degree
    -D SPI_FREQUENCY=80000000
    -D SPI_TOUCH_FREQUENCY=2500000
    -D USER_SETUP_LOADED=1
    -D TOUCH_DRIVER=2046 ; XPT2046 Resistive touch panel driver
    -D SUPPORT_TRANSACTIONS

HASP build_flags~

Specify the LCD Configuration to use and define the 7 GPIOs in the environment build flags:

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build_flags =
    ${flags.esp32_flags}
; -- TFT_eSPI build options ------------------------
    ${lcd.raspberrypi}
    ${esp32.vspi}        ; Use VSPI hardware SPI bus
    -D TFT_CS=15
    -D TFT_DC=4
    -D TFT_RST=32
    -D TFT_BCKL=-1       ; None, configurable via web UI (e.g. 21)
    -D TOUCH_CS=22
Last update: 2022-06-04
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