Skip to content

MHS4001

6 GPIOs are required to drive the SPI display. One additional GPIO is needed for the XPT2046 touch sensor. Including the Vcc and Gnd pins, a total of 12 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 LED Backlight PWM 5V TFT_BCKL 5V
5-10 Not connected NC
11 Touch Interrupt NC TP_IRQ
12-13 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

By default, pin 4 is normally connected to 5V. This turns the display backlight LED on all time. In order to control the backlight you can drive pin 4 of the display using a PNP transistor. The electronics circuit needed is not part of this diagram.

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

LCD Configuration~

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

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
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:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
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
    -D TOUCH_CS=22
Last update: 2023-12-09