ESP32 CYD ST7796 3.5-inches resistive touch display

This is an ESP32 Dev. Board with assembled ST7796 3.5-inches TFT display with SPI interface that has a resolution of 320 x 480 pixels and resistive touch surface (driver chip XPT2046). It is known as Cheap Yellow Display (“CYD”) and comes in several variants, this is ESP32-3248S035. Additionally, a Micro-SD-Card reader and a (true) RGB LED is on the backside of the device. There is an LDR Light sensor assembled on the front side, but a lot of people marked them as not working or useless (I did not verify this).

Please note that there are no breadboard pins that expose GPIO pins, instead there are 3 JST 1.25 connectors available.

ESP32 CYD pin mapping overview

Please find the pin mapping overview here

Documentation

This board is well documentated by the manufacturer and third party persons:

• Developer website: this specific device has the “device number” “ESP32–3248S035”, that was developed by a Chinese company. Their website is difficult to find, here is a link to the folder (containing all models) and the specific product file. You will download a file of about 108 MB size!
• Probably the best website about the CYD is from a hobbyist, “witnessmenow” (Brian Lough), who maintains the GitHub repository “ESP32-Cheap-Yellow-Display” with a lot of FAQs and troubleshooting around CYD
• Another source for examples is “https://github.com/bitbank2/CYD_Projects”
• Sara and Rui Santos have a phantastic website around ESP32 topics, and they give a lot of information and examples, e.g. “Getting Started with ESP32 Cheap Yellow Display Board — CYD (ESP32–2432S028R)” and “ESP32 Cheap Yellow Display (CYD) Pinout (ESP32–2432S028R)”. Use their search for more tutorials on this device.
• Freenove ESP32 tutorial (19 different tutorials tested on ESP32 CYD)
• Hartmut Waller A lot of examples for the display, RGB LED and SD-Card reader
• Modifications to the original CYD (audio e.t.c): ESP32_TFT_PIO
• Macsbug ESP32-3248S035: a lot technical stuff, very helpfull

Own tutorials

I wrote some tutorials regarding this device:

• Create a colorful digital clock on an ESP32 Cheap Yellow Display (“CYD”)
• Create an Internet Weather Station with 3 days Forecast on an ESP32 Cheap Yellow Display (“CYD”)
• How to use Touch and SD Card at the same time on an ESP32 Cheap Yellow Display (“CYD”)
• Play iconic Arcade Games like Pac-Man or Donkey Kong on ESP32 Cheap Yellow Display (“CYD”) [full guide]
• Create a digital clock in a Domino style on an ESP32 Cheap Yellow Display (“CYD”)
• Playing Othello / Reversi on an ESP32 Cheap Yellow Display with Minimax intelligence for the AI opponent

Libraries

The following libraries and version numbers are tested with this board:

• TFT_eSPI by Bodmer, version 2.5.43, https://github.com/Bodmer/TFT_eSPI
• LovyanGFX by Lovyan03, version 1.2.7, https://github.com/lovyan03/LovyanGFX

Development board profile

Position	Characteristics
Processor:	ESP32 module with dual-core Xtensa LX7 (ESP32-D0WD-V3 (revision v3.1)), Flash 4 MB, no PSRAM
CPU Frequencies	160/160/80 MHz (for WiFi), 40/20/10 MHz (no WiFi)
Pins available on Breadboard	0, 4, 5, 12, 16, 17, 18, 19, 21, 22, 23, 25, 26, 27, 32, 33, input only: 34, 35, 36, 39 (total 20), 3.3V, 5V, GND
Pins available on solder pads	NO
Pins available internally	0 (BOOT button) and display (see below)
Pins for ST7789	BL: 21, MISO: n/c, MOSI: 13, SCLK: 14, CS: 15, DC: 2, RST -1, HSPI-port, 80 MHz
Pins for XPT2046 Touch Controller	MISO: 39, MOSI: 32, SCLK: 25, SS/CS: 33, IRQ: 36
Pins for Micro-SD-Card reader	MISO: 19, MOSI: 23, SCLK: 18, SS/CS: 5
Pin for Light sensor	34
Pin for Speaker amplifier	26 (no direct usage)
Pins safe to use	22,27 and 35 (input only) on CN1
Display	YES, ST7789 1.9-inches display, SPI interface, 170x320 pixels, no touch controller
Interfaces	1x I2C, 2x SPI, 2x UART, 11x GPI0 (PWM), 4x ADC
Onboard Power LED	NO
Onboard GPIO LED	RGB LED, red: 4, green: 16, blue: 17
USB-Connection	USB-C and Micro-USB, Controller: CH340
Wi-Fi connector	PCB antenna
Wi-Fi	YES, 802.11 b/g/n (2.4 GHz), STA/AP/Mixed
Bluetooth Classic	YES, 5.0
Bluetooth Low Energy (BLE)	YES, Bluetooth 5.0 LE protocols
Battery connector	NO
Battery loading	NO
Battery voltage measure	NO
Battery voltage measure control	NO
Extern voltage control	NO
Restart button	YES
BOOT button	YES, GPIO 0
On-/Off Switch	NO
SD card reader	YES
Breadboard pins	NO pins but some 1.25 JST connectors
QWIIC connector	NO
Internal temperature sensor	YES
Low Dropout Voltage Regulator (LDO)	AMS1117 (1000 mA)
Breadboard pins distance (width)	3,0 cm (does not fit on one breadboard)
Security features	Encryption hardware accelerators that support AES-128/256, hashing, RSA, HMAC, digital signatures, and secure startup
Expansion board	NO
Arduino board selection	ESP32 Dev Module

ESP32 CYD back side pins

Schematic

esp32_cyd_st7796_3_5_inches_schematic.pdf