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LaskaKit ESPlan is an industrial-grade ESP32 development board built around the ESP32-WROOM-32E module. It combines wired Ethernet (LAN8720A), an isolated RS485 bus, Wi-Fi + Bluetooth, and three independent ways to power the board – including optional PoE. It is designed for industrial automation, IoT gateways, home automation (Home Assistant, ESPHome) and remote sensor nodes where reliable wired connectivity without dependence on Wi-Fi is required.
Designed and manufactured in the Czech Republic 🇨🇿
Product page: https://www.laskakit.cz/laskakit-esplan-esp32-lan8720a-max485-poe/
ESPlan v2.1 supports three power sources that can be combined freely. The source with the highest voltage is always active.
| Source | Input voltage | Path to the board | Typical use |
|---|---|---|---|
| USB-C | 5 V | direct to the 5 V rail | development, programming |
| Screw terminal (+12/24 V, GND) | 7–40 V DC (12 or 24 V recommended) | step-down LMR14050 (up to 5 A) → 5 V → LDO XC6220 → 3.3 V | industrial PSU, DIN rail |
| PoE (Power over Ethernet) | via optional SDaPo DP9900M module (12 V or 24 V variant, sold separately) | PoE module output → same buck converter as the terminal | power straight from the LAN cable |
PoE note: We recommend the 24 V variant of the DP9900M – it better matches the converter input range and gives higher efficiency. The module meets IEEE 802.3af (up to 12.95 W), is galvanically isolated, and works with any PoE switch or injector.
The whole power chain is protected: terminal inputs are fused with a polyfuse, and the RS485 bus has TVS diodes (PSM712) and a polyfuse (MF-MSMF010-2) against overvoltage and shorts from the external line.
See annotated diagrams in img/power/ for each option.
The RS485 terminal has three pins: GND, A, B.
- A and B are NOT power pins – they carry the differential data signal from the isolated WS3081 transceiver. At idle the A−B difference is ~0 V; while transmitting, |A−B| is roughly 1.5–3 V under load (per the RS485 standard the driver outputs ≥1.5 V differential, receivers detect ±200 mV, common-mode range −7 V to +12 V). There is no usable supply voltage on A/B.
- Powering a remote RS485 device: the terminal block also brings out 12/24 V IN/OUT, so the same voltage you use to power the ESPlan (12 or 24 V) can be looped out to power a field sensor over the same run. If your sensor needs a different voltage (e.g. 5 V), use a local regulator at the sensor.
- Bus wiring: connect A↔A, B↔B, GND↔GND. At the end of a long run enable the on-board 120 Ω termination with the BUS_TERM jumper – no external terminator needed.
- Ethernet – LAN8720A PHY (Fast Ethernet 10/100 Mbps), HanRun RJ45 with integrated magnetics and status LEDs.
- RS485 – fully isolated WS3081 transceiver with TVS protection, screw terminal (GND, A, B), on-board 120 Ω termination via the
BUS_TERMjumper. - Wi-Fi + Bluetooth – built into the ESP32-WROOM-32E (2.4 GHz Wi-Fi 802.11 b/g/n, Bluetooth 4.2 / BLE).
- microSD card – slot over SPI with card-detect.
- I²C connector – dedicated 4-pin connector (3.3 V, GND, SCL, SDA) with pull-ups for sensors, displays, etc.
- µSup connector – SPI connector for the optional supercapacitor module (µSup) for short backup during power loss.
- GPIO header – all free ESP32 pins broken out on a populated header.
| Function | GPIO |
|---|---|
| I²C SDA / SCL | IO33 / IO32 |
| SPI MISO / MOSI / CLK / CS | IO12 / IO13 / IO14 / IO15 |
| microSD MISO / MOSI / CLK / CS / CD | IO12 / IO13 / IO14 / IO2 / IO34 |
| Ethernet MDC / MDIO / NRST / CLK | IO23 / IO18 / IO5 / GPIO17 (out) |
| User LED (SK6812) | IO0 |
| Input-only pins | IO34, IO35, IO39 |
- RESET button – resets the ESP32.
- IO0 / BOOT button – enter firmware upload mode (RESET + IO0).
- Status LED (SK6812) on IO0 – programmable user LED.
Ethernet init (Arduino core 2.x): the LAN8720A clock is on GPIO17. A known-good call is:
ETH.begin(0, -1, 23, 18, ETH_PHY_LAN8720, ETH_CLOCK_GPIO17_OUT);On newer cores use the named-enum signature, e.g.
ETH.begin(ETH_PHY_LAN8720, ETH_ADDR, ETH_MDC_PIN, ETH_MDIO_PIN, ETH_POWER_PIN, ETH_CLOCK_GPIO17_OUT);I²C init:
Wire.begin(33, 32);
| MCU | ESP32-WROOM-32E (Xtensa LX6 dual-core 240 MHz, 4 MB Flash, Wi-Fi + BT) |
| Ethernet PHY | LAN8720A-CP, Fast Ethernet 10/100 Mbps |
| RS485 | WS3081, half-duplex, isolated, TVS protection, optional 120 Ω termination |
| Power – USB-C | 5 V |
| Power – terminal | 7–40 V DC (12 or 24 V recommended) |
| Power – PoE | IEEE 802.3af via DP9900M module (12 V or 24 V variant, sold separately) |
| Internal rails | 5 V (buck LMR14050, up to 5 A) → 3.3 V (LDO XC6220) |
| microSD | SPI, connector with card detect |
| Programming | USB-C with on-board USB-UART bridge (auto-boot), RESET + BOOT buttons |
| Compatibility | Arduino IDE, ESP-IDF, ESPHome, Tasmota, MicroPython |
- 1× LaskaKit ESPlan v2.1
The PoE module (SDaPo DP9900M) and the 3D-printed enclosure are not included – ordered separately.
STL/3MF files for the enclosure are in the 3D folder.
Open-source hardware by LaskaKit. Questions, issues and pull requests are welcome via the Issues tab.