Guðjóns site

Last modified: 3.4.2025

Started: 29.9.2023

A smart pet feeder with scheduling, remote management, and an LCD display.

The project is hosted on GitLab under the repository food-dispenser. For development details, see the development document.

The project is transitioning from an ESP32 microcontroller to an ESP32-S3-DevKitC-1-N8R2 or N8R8. The N8 variant, with its 3.3V SPI voltage, was selected to streamline PCB design. The original ESP32 implementation encountered memory constraints, hindering the implementation of all intended features. The ESP32-S3's enhanced memory and processing capabilities should enable the full feature set.

Challenges & Next Steps

Testing the ESP32-S3 for memory capacity and compatibility with the current touch display
- Wire a display to ESP32-S3, display something on the display and detect touch events. See research that started 2025-03-13 Display & Touch below.
- Working on Reading and writing from SD-card to test better multiple SPI on same bus. See research that started 2025-03-14 Display & Touch & SD-card below.
Check if it's better to use LVGL library on top of TFT_eSPI library in PlatformIO
- Make a hello world example with LVGL. See research that started 2025-03-22 LVGL library world using Display with Touch
- Create some pages with the LVGL widgets to find out memory usage is better or easier using the LVGL library. 2025-03-28
- Learn which widgets exists, how to use and style them and which one is probably needed for the project. Finisied 2025-03-30
Create a new project hunifood-s3 setup the display and check if display and esp32-s3 works with the old pcb
- Figured out how best to create and structure the new hunifood-s3 project, add pages and widgets and added display pagesRssiWidget to check if the project structure works and is testable with unity Finisied 2025-04-02.
- Figure out how to create my own widgets, where to place them in a way they can be tested with unity Finisied 2025-04-03.
  - Created a RssiWidget to show the RSSI value of the ESP32-S3 and added it to the main page, and added that widget to MainMenuPage and WifiPage. Finisied 2025-04-03.
  - Plug the new display to the old PCB and Remove the old esp32 from the two seats on the PCB and wire the new esp32-s3 to the seats where the old esp32 was using dupont wires.
  - Test if the current hunifood-s3 project (the software) works with the old PCB and the new ESP32-S3, and the new ST8896 display.
  - Add gradually, the old software components, to the new project, test if they work and if they communincate correctly with the hardware components connected to the old PCB.
Re-issue milestone deadlines
Continue with Milestone 5 of project on GitLab, find out how we get back on track
Rewiring and integrating the new microcontroller with components
Redesigning the PCB for the ESP32-S3

Project Progress & Milestones

First Prototype: Display, Portioning, and Servo Motors with Load Cell

Initial wiring and software development. Integration and testing of display, portioning mechanism, and load cell.

PCB Design & Assembly: Custom PCB designed for the ESP32, with power LED confirmed functional

Custom PCB designed for the ESP32. Power LED confirmed functional, but no components installed yet. Transitioning to ESP32-S3 requires PCB modification.

Software & Hardware Integration: Testing communication between software and physical components, with motor, sensor, and display functionality verified

Testing communication between software and physical components. Verifying motor, sensor, and display functionality. Load cell readings still require tuning.

Research

2025-03-13 Display & Touch

Purpose: Test if I can get a display and touch working on the ESP32-S3 because the ESP32-S3 has a lot more memory than the ESP32. This was pretty hard to get working. The library always crashed on init() and it took me a while to figure out what was wrong.

Using a 4.0 inch 480*320px SPI Module ST7796 with an ESP32-S3-DevKitC-1-N8R2.

To be able to use the Display with 3.3V I needed to short J1 on the board, circumventing the 5V voltage regulator on the display.

In order to be able to chain more devices to the SPI bus this display uses to show Graphics and detect touch events I needed to remove a diode marked D1 from the display and short the remaining connections. See TFT_eSPI issue 898

I wired the display to the ESP32-S3 like this:

ESP32-S3 Pin	TFT Connection	Touch Connection
3	-	T_IRQ
12	TFT MISO	T_DO
6	TFT MOSI	T_DIN
10	-	T_CS
5	TFT SCLK	T_CLK
7	TFT RST	-
8	TFT DC	-
15	TFT CS	-

I do not use the User_Setup.h file to define pins for the display, instead I use the platformio.ini which I think is a much clear and better way to define all important project Settings which allows us for example to have all pin definitions in one place.

// Coming soon

Result 1 - 2025-03-14

I consider this test as a Success because using the TFT_eSPI library examples the I was able to show something on the display and detect touch events.

2025-03-15 Display & Touch & SD-card

Purpose: Test if I can put more devices on the SPI bus, the test will be adding an SD-card using the same display and same controller as in the previous test

I wired the display to the ESP32-S3 like this:

ESP32-S3 Pin	ST7796 Display Connection	XPT2046 Touch Connection	SD Card (SPI)	Function
GPIO 3	-	T_IRQ	-	Touch Interrupt Request
GPIO 12	TFT MISO	T_DO	SD_MISO	SPI MISO
GPIO 6	TFT MOSI	T_DIN	SD_MOSI	SPI MOSI
GPIO 10	-	T_CS	-	Touch Chip Select
GPIO 5	-	-	SD_CS	SD Card Chip Select(SPI)
GPIO 7	TFT RST	-	-	Reset
GPIO 8	TFT DC	-	-	Data/Command Select
GPIO 15	TFT CS	-	-	Display Chip Select
GPIO 4	TFT SCLK	T_CLK	SD_SCK	SPI SCLK
3.3V	VCC	VCC	VCC	Power Supply
GND	GND	GND	GND	Ground

Added the following capacitors to the circuit to stop SD-card failure:

0.1µF capacitors between the TFT VCC and GND pins close to the display.
10µF capacitors between the TFT VCC and GND pins close to the display.
0.1µF capacitors between the 3V3 and GND pins close to the MCU.
1000µF capacitors between the 3V3 and GND pins close to the MCU.

I put the definitions for all pins in the platformio.ini including SD-card pins.

// Coming soon

And some code using the display, touch and reading files from SD-card

// Coming soon

Some Serial output from the device after running the code and pressing the screen a few times

// Coming soon

Result 2 - 2025-03-16

I am not sure about the result, could be a possible success, because I was able to read from the sd card, display images on the display and detect touch events. But sometimes mounting the sd-card failed, possibly because of the loose wiring and bad connections in the bread-board.

Result 3 - 2025-03-17

SD-card failure has stopped, the result is a success. I added 0.1µF and 10µF capacitor between the TFT VCC and GND pins close to the display. I added also 0.1µF and 1000µF capacitors between the 3V3 and GND close to the MCU.

2025-03-22 hello LVGL library world using Display with Touch

Purpose: Learn how to create basic display pages using the LVGL library with the ESP32-S3 and ST7796 display.

This test includes two parts: displaying content on the screen, and displaying content with touch detection. I will demonstrate this with two main.cpp files: main-display.cpp for basic display output, and main-touch.cpp for display output with touch input handling.

Both main-*.cpp files use the same configuration files: platformio.ini and include/lv_conf.h.

Same as in the above example, I put the definitions for all pins in the platformio.ini and the wiring is the same.

The shared files

// Coming soon

// Coming soon

Displaying a label from the LVGL library

// Coming soon

Serial output from the main-display.cpp code

// Coming soon

Displaying a button and detecting touch event when button is clicked using the LVGL library

// Coming soon

// Coming soon