RPi 3.5 inch Display with ESP32

References

• 3.5" RPi Display User Manual
• 3.5" RPi Display
• SKU: MPI3501
• Touch Chipset: XPT2046
• Driver IC: ILI9486

In My Project

• Library: TFT_eSPI
• TFT_eSPI User Setup: Setup11_RPi_touch_ILI9486.h

MPI3501 Pins

These took some working out. The above two reference documents each had some parts but neither was clear about what pin 22 was for. Plus a bit of trial and error, I managed to get it working.

Description	#	#	Description
Power Input 5v	2	1	Power Input 3.3v
Power Input 5v	4	3	SDA
GND	6	5	SCL
TX	8	7	P7
RX	10	9	GND
P1	12	11	P0
GND	14	13	P2
P4	16	15	P3
LCD Reset LCD_RST	18	17	Power Input 3.3v
GND	20	19	Touch Panel Input MOSI
Touch Panel Reset TP_RST	22	21	Touch Panel Output MISO
LCD Chip Select LCD_CS	24	23	Touch Panel Clock SCLK
Touch Panel Chip Select TP_CS	26	25	GND

ESP32 Connections

ESP32 Pin	Display Pin
D23	#19 Touch Panel Input MOSI
D22	#26 Touch Panel Touch Panel Chip Select TP_CS
D19	#21 Touch Panel Output MISO
D18	#23 Touch Panel Clock SCLK
D4	#22 Touch Panel Reset TP_RST
D2	#18 LCD Reset LCD_RST
D15	#24 LCD Chip Select LCD_CS
VIN	#2 5v
GND	#6 GND

Code

My code displays a simple button on the screen which, when clicked, sends a message to an MQTT broker which is attached to Home Assistant via the MQTT integration. I have an Automation set up on my Sonoff (eWeLink) switch to toggle the switch on receiving this message. Also set up in Home Automation is the StateStream integration which publishes the change of state of the switch, which my code listens to and changes the colour of the button appropriately.

My code contains examples of how to:

• Store credentials in Preferences
• Connect to WiFi
• Run a touch screen
• Set hostname via mDNS (not much use as there's nothing listening in my code)
• Connect to an MQTT broker
• Both publish and subscribe to the MQTT broker
• Calibrate a touchscreen and store the data in LittleFS

Entirely based on the examples from TFT_eSPI, PubSubClient and some others I don't remember.

• Within TFT_eSPI Arduino library, copy User_Setups/Setup11_RPi_touch_ILI9486.h over User_Setup.h
• My code
• State Stream setup in Home Assistant's configuration.yaml

mqtt_statestream:
  base_topic: homeassistant
  publish_attributes: true
  publish_timestamps: true
  include:
    domains:
        - switch
    entities:
        - switch.sonoff_1001ffea20_1