ESP32 board with rotary encoder gets 2-key keypad shield

LILYGO TTGO T-Encoder, a round-shaped ESP32 board with a built-in rotary encoder, has gotten a shield with a 2-key keypad based on WCH CH552 8-bit microcontroller.

Launched several months ago, the TTGO T-Encoder is a USB-powered rotary encoder with ESP32 microcontroller offering WiFi and Bluetooth connectivity, and now, you can build a keypad with rotary encoder thanks to T-Encoder shield that features two mechanical switches and keycaps with RGB LED backlight.

T-Encoder ESP32 keypad rotary encoder


Since we missed it at launch, let’s check out the tiny TTGO T-Encoder board specifications first:

  • System-in-Package (SiP) – Espressif ESP32-PICO-V3-02 with
    • MCU – ESP32 Xtensa dual-core 32-bit Xtensa LX6 microcontroller up to 240 MHz, 448 KB ROM for booting and core functions, 520 KB SRAM for data and instructions, 2.4 GHz WiFi 4 and Bluetooth 4.2 BR/EDR + LE connectivity
    • Memory – 2MB SPI PSRAM
    • Storage – 8MB SPI flash
    • Dimensions – 7×7 mm
  • Antenna – Ceramic antenna
  • USB – 1x USB Type-C port for power and programming
  • Rotary encoder with built-in button
  • Expansion – 2x 4-pin (male or female) headers with up to 6x GPIO, UART, SPI, I2C
  • Misc – 2x WS2812 RGB LEDs, Reset button, buzzer
  • Power Supply – 5V via USB Type-C port
  • Dimensions – 25.8mm Ø x 12.8mm H

TTGO T-Encoder ESP32 rotary encoder board

The T-Encoder is programmable with Arduino or PlatformIO with examples and basic documentation available on Github. Since the board does not come with a USB to TTL chip, you’ll need the usual T-U2T tool if you want to flash the firmware to the board.

The T-Encoder shield comes with the following specifications:

  • MCU – WCH CH552 8-bit E8051 USB device microcontroller with 16KB ROM, 128B DataFlash, 1KB xRAM, 256B iRAM
  • User input
    • 2x customizable macro keys with APA102 RGB LED
    • 2x 4-pin male headers for TTGO T-Encoder board (UART)
  • USB – 1x Micro USB port for power and connection to host
  • Misc – Run/download mode switch
  • Power Supply – 5V via USB
  • Dimensions – 7.8 x 3.26 x 2.4 cm

T-Encoder Keypad Shield

The CH552 microcontroller on the shield itself is programmable with Keil (C programming) or the Arduino IDE as explained on Github, where you’ll find code samples for both, as well as PDF schematics.

This type of solution can be used to simulate shortcuts for example one key assigned to Control+C, the other to Control+V to speed up copy and paste operations. The T-Encoder board is actually optional but would allow to user to browse a list more efficiently, control volume, improve the productivity of video editing, and so on. It should also be possible to convert the solution into a Bluetooth keypad instead of just a USB one.

T-Encoder Shield keypad with RGB LEDs
T-Encoder Shield keypad working in standalone mode without the ESP32 rotary encoder

The T-Encoder shield is sold in limited quantities on Aliexpress for about $13 including shipping, while the ESP32-based TTGo T-Encoder rotary encoder board goes for around $12, but if you may want to spend $5 extra to get a T-U2T downloader tool if you don’t own one already.

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