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 Pin : This 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 Pin : Operates as Active Low; controlling this pin allows entry into AT command mode via serial for chip control.
-
RP BOOT Pin : The reset pin for internal flash memory, operating as Active Low, following the RP2040 boot sequence.
-
232/485 Select Pin : Determines 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 Pin : Resets the IP settings to factory defaults while keeping the firmware unchanged.
Data Pin
The selection between SPI mode and UART mode can be determined at boot by reading the state of the UART_SPI_SEL pin.
| Pin | Pinout | Name | Description |
|---|---|---|---|
| UART_SPI_SEL | 19 | GP13 | UART/SPI interface select pin High:SPI, Low/NC:UART |
UART mode
| 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)
SPI mode
| Pin | Pinout | Name | Description |
|---|---|---|---|
| SPI_SCK | 67 | GP2 | SCK input pin for Data SPI transmission |
| SPI_MISO | 68 | GP3 | MISO pin for Data SPI reception |
| SPI_MOSI | 9 | GP4 | MOSI pin for Data SPI transmission |
| SPI_CSn | 10 | GP5 | SPI Chip Select pin |
| SPI_INT | 46 | GP26 | SPI Master Recv data pending pin |
LED Indicators - Status
| Pin | Pinout | Name | Description |
|---|---|---|---|
| RUN | 41 | 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.