1.85" 360x360 TFT ESP32-S3 Round Smart Display

1. Introduction

The ESP32-S3 Round Dev Board is a circular, 70 mm diameter development board that carries the ESP32-S3-WROOM-1 (N16R8) module on one side and a single round display on the other. The same PCB accepts three different round panels, and this page covers the 1.85-inch TFT build: a 360x360 a-Si TFT panel driven by an ST77916 controller over a 4-bit QSPI bus, with capacitive touch on I2C.

This is the largest of the three round panels, with a 45.68 x 45.68 mm display area, and the only one that uses a transmissive TFT rather than an emissive AMOLED. At 127 PPI the pixels are visibly larger than on the two AMOLED options, which makes it a good fit for gauge-style interfaces, large-type readouts and cost-sensitive products where a full circular graph is more useful than a high pixel density. Typical brightness is 400 cd/m².

The board keeps the full peripheral set: digital MEMS microphone, I2S DAC and class-D amplifier for an 8 Ω / 2 W speaker, 6-axis IMU, SD3078 real-time clock with a rechargeable backup-cell socket, TF card slot and an RGB status LED. Power comes from USB Type-C or a battery, with automatic changeover and charging.

The repository ships standalone ESP-IDF bring-up projects for each panel size, and the 1.85-inch build maps to examples/esp-idf/ESP32-S3-Round-Dev-Board/viewe1.8.

1.1 Product Features

Processor & Wireless

• Processor: ESP32-S3-WROOM-1, marked ESP32-S3-N16R8. Xtensa® dual-core 32-bit LX7 up to 240 MHz.
• Wireless: 2.4 GHz Wi-Fi (802.11 b/g/n) and Bluetooth 5 (LE).

Memory

• Flash: 16 MB.
• PSRAM: 8 MB.
• On-chip: 520 KB SRAM, 448 KB ROM.

Display

Peripherals

• Audio in: onboard digital MEMS microphone on I2S.
• Audio out: I2S DAC plus class-D amplifier, MX1.25 2-pin speaker connector rated for an 8 Ω / 2 W speaker.
• Motion: QMI8658 6-axis inertial sensor (accelerometer + gyroscope) on I2C.
• Timekeeping: SD3078 real-time clock with a socket for a rechargeable backup cell.
• Storage: TF (micro SD) card slot.
• Expansion: USB_OTG interface, plus IO3, IO8, IO43 and IO44 broken out for SPI / I2C / I2S / UART.
• Indication: onboard RGB LED used for status signalling.
• Buttons: PWR (power), BOOT (download mode) and RST (hardware reset).

Other

• Power supply: DC 5 V through USB Type-C, or a battery with onboard charge and discharge management. USB takes priority when both are connected.
• Operating current: 1100 mA while charging at VCC = 5 V; 210 mA in non-charging operation. A 5 V / 1 A supply is recommended.
• Board size: Ø70 mm circular PCB.
• Operating temperature: -20 ~ 70 ℃
• Storage temperature: -30 ~ 80 ℃
• Environmental: RoHS 2.0 and halogen-free.
• ESD: ±4 kV contact, ±8 kV air.

1.2 Applications

A large, bright circular TFT with an audio front end, battery support and motion sensing suits products that need a legible round readout rather than a photographic image:

• Round gauges, meters and instrument dials
• AI voice assistants and desktop companion devices
• Smart home control dials, thermostats and scene controllers
• Industrial HMI for pumps, valves and environmental monitors
• Wearable and pendant-format concepts
• Portable, battery-powered sensor readouts

2. Hardware Description

2.1 Module Overview

The board is a single circular PCB with one panel mounted on the front. The numbered callouts below mark each functional block on the back of the board:

2.2 GPIO Definition (Pinout)

The table below is the GPIO assignment summary from the board specification, colour-coded by function:

Display (QSPI)

All three panel options share the same QSPI bus on the board, so the pin assignment below is identical no matter which panel is fitted.

The ST77916 is addressed in QSPI mode with four data lines, and the shipped example drives it at 360 x 360 with 16 bits per pixel.

Touch

Audio

Sensors, Storage and Host Interfaces

2.3 Board Dimensions

The PCB is a circle 70 mm in diameter. The 1.85-inch TFT module measures 48.08 x 49.95 x 2.12 mm and its active area is 45.68 x 45.68 mm, so it is the widest of the three options and overhangs the board outline slightly. For comparison, the 1.5-inch AMOLED module is 44.3 x 44.3 x 2.405 mm and the 1.75-inch AMOLED module is 45.93 x 46.35 mm.

3. Software

The repository ships standalone ESP-IDF projects, one per panel option. The 1.85-inch TFT build lives in examples/esp-idf/ESP32-S3-Round-Dev-Board/viewe1.8 and bundles the ST77916 panel driver as a local component, so no external BSP download is required.

3.1 Software Examples

Examples are available in the GitHub Repository.

The 1.85-inch project vendors these components under components/: esp_lcd_st77916 (panel), lvgl, qmi8658 (IMU), sd3078 (RTC).

3.2 Getting Started

3.2.1 Preparation

• Hardware: ESP32-S3 Round Dev Board with the 1.85-inch TFT fitted, a USB-C cable, and optionally an 8 Ω / 2 W speaker and a rechargeable RTC cell.
• Software: VS Code with the ESP-IDF extension and ESP-IDF v5.1 / 5.2 / 5.3, or the standalone idf.py toolchain.
• Power: Use a 5 V / 1 A supply. Peak current while charging is around 1100 mA, and this panel draws noticeably more than the AMOLED options when running — about 210 mA against 130 mA.

3.2.2 ESP-IDF Setup

1. Open the example folder in VS Code — examples/esp-idf/ESP32-S3-Round-Dev-Board/viewe1.8.
2. Set the target to esp32s3.

3. Build, flash and monitor. From the command line inside the example directory:

   idf.py set-target esp32s3
   idf.py build flash monitor
   

If the board does not enter download mode automatically, hold BOOT, tap RST, release BOOT, then start the flash.

3.2.3 Arduino Setup

The repository does not ship Arduino examples for this board, and the board is not yet in the Espressif ESP32_Display_Panel supported-board list, so there is no ready-made BOARD_VIEWE_* macro to select. Arduino is still usable — the panel is a standard QSPI ST77916 device — but you supply the pin map yourself:

1. Install Arduino IDE and add the ESP32 board package:

   https://espressif.github.io/arduino-esp32/package_esp32_index.json
   

2. Select the board: target ESP32S3 Dev Module, with Flash Size 16MB (128Mb) and PSRAM OPI PSRAM. Getting the PSRAM mode wrong leads to a board that boots but never allocates a frame buffer.

3. Install the libraries: ESP32_Display_Panel and lvgl (v8.4.0 recommended).
4. Configure the board: in esp_panel_board_supported_conf.h, keep ESP_PANEL_BOARD_DEFAULT_USE_SUPPORTED at 0 and fill in esp_panel_board_custom_conf.h using the pin table in 2.2 GPIO Definition — QSPI with a single CS line for the panel, and I2C on IO17 / IO18 for touch.
5. Compile and upload with the USB-C cable connected.

3.2.4 PlatformIO Setup

PlatformIO works the same way as the Arduino route: use a generic ESP32-S3 environment and provide the board definition yourself.

1. Create a platformio.ini with board = esp32-s3-devkitc-1 and set board_build.arduino.memory_type = qio_opi so the octal PSRAM is used.
2. Add -D BOARD_HAS_PSRAM and -D ARDUINO_USB_CDC_ON_BOOT=false to build_flags so the serial console stays on UART0.
3. Add ESP32_Display_Panel and lvgl to lib_deps, then configure the custom board header as in the Arduino route.

4. Related Documents & Resources

5. Firmware Download

1. Open the tools folder of the repository and locate the ESP32 flash download tool (flash_download_tool_3.9.5). Extract and launch it.
2. Select the chip type ESP32-S3 and the download mode, then click OK. Follow the numbered steps 1 → 2 → 3 → 4 → 5 shown below to burn the firmware. If the download fails, hold the BOOT button and try again.
3. Select the binary to burn. Prebuilt binaries, when published, are placed in the repository's firmware directory — check the version notes inside and choose the appropriate build.

If no prebuilt binary is available, build and flash from source instead — see 3.2 Getting Started.

6. FAQ