LILYGO T-Relay
ESP32 development board with 4 onboard HRS4H-S-DC5V relays, 4MB flash, 8MB PSRAM, WiFi, BLE 4.2, and optocoupler-isolated GPIO expansion — designed for wireless remote switch control of AC/DC loads.
$10.01
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Specifications
Components
Dual-core 240MHz Xtensa LX6 with WiFi and BLE 4.2
4 groups of DC 5V HRS4H relays with blue LED indicators, controlled via dedicated GPIO pins with optocoupler isolation
USB to serial converter for programming and debug output
Bus Interfaces
Overview
The LILYGO T-Relay is an ESP32-based relay control board featuring 4 groups of HRS4H-S-DC5V relays with blue LED status indicators. Each relay is mapped to a dedicated GPIO pin (K1→GPIO21, K2→GPIO19, K3→GPIO18, K4→GPIO5), and the board includes 16 expansion GPIO pins with optocoupler isolation for safe interfacing with external circuits. Powered via DC 5V, it connects over WiFi 802.11 b/g/n and BLE 4.2, with support for UART, SPI, I2C, CAN, I2S, and SDIO interfaces. Programming is done via the T-U2T USB-to-TTL programmer (sold separately) or any compatible USB-serial adapter.
Use Cases
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