W55RP20 Serial to Ethernet Official Design Guide
Introduction
The W55RP20 combines WIZnet’s W5500 Ethernet controller and Raspberry Pi’s RP2040 MCU, designed specifically for Serial-to-Ethernet applications supporting UART TTL, RS-232, RS-422, and RS-485 communication.
Pinout Description
Setting Pin
| Pin | Pinout | Name | Description |
|---|---|---|---|
| RST | 29 | RUN | MCU Reset (Active Low) |
| BOOT Mode | 21 | GP15 | Firmware boot mode control |
| AT Mode | 20 | GP14 | Enter AT command mode (Active Low) |
| RP BOOT | 63 | BOOT | Flash reset & RP2040 boot (Active Low) |
| 232/485 Select | 18 | GP12 | Low: TTL/RS-232, High: RS-422/485 |
| Factory RST | 40 | GP18 | Reset IP settings (Firmware retained) |
-
RST PinThis pin is used for MCU reset and operates in an Active Low state.
-
BOOT Mode PinDesigned to control the boot mode of the Serial to Ethernet internal firmware.
-
AT Mode PinOperates as Active Low; controlling this pin allows entry into AT command mode via serial for chip control.
-
RP BOOT PinThe reset pin for internal flash memory, operating as Active Low, following the RP2040 boot sequence.
-
232/485 Select PinDetermines the communication method based on its state at initial chip operation.
- Low: Sets UART or RS-232 mode
- High: Sets RS-422 or RS-485 mode
-
Factory RST PinResets the IP settings to factory defaults while keeping the firmware unchanged.
Data Pin
| Pin | Pinout | Name | Description |
|---|---|---|---|
| UART_TX | 9 | GP4 | UART data transmission. |
| UART_RX | 10 | GP5 | UART data reception. |
| UART_RTS | 12 | GP7 | UART request to send (flow control) |
| UART_CTS | 11 | GP6 | UART clear to send (flow control) |
| UART_DTR | 14 | GP8 | UART data terminal ready (flow control) |
| UART_DSR | 15 | GP9 | UART data set ready (flow control) |
- UART_RTS Pin: UART request to send (flow control); determines communication mode (floating for RS-485, Low for RS-422)
LED Indicators - Status
| Pin | Pinout | Name | Description |
|---|---|---|---|
| RUN | 19 | GP19 | MCU status LED, blinks when the MCU is operating normally. |
| PHY LINK | 16 | GP10 | Indicates PHY link status |
| TCP Conectoin | 17 | GP11 | Indicates active TCP connection |
Firmware Upload
Three firmware upload methods:
-
USB (UF2)
- Set RP-BOOT pin Low and reset; drag
Boot.uf2and thenapp.uf2into ‘RPI-RP2’ drive.
- Set RP-BOOT pin Low and reset; drag
-
SWD (J-Link)
- Upload HEX/BIN files using J-Link, same as standard RP2040.
-
Ethernet (BIN)
- Use WIZnet Configuration Tool for application updates only (not initial upload).
MAC Address Setup
Initial firmware upload via USB/SWD required. MAC setup essential via WIZnet MAC Tool (115200 baud). MAC address must be purchased separately.
Configuration
Advanced settings and further configurations available using the latest WIZnet Configuration Tool.