---
title: "W55RP20-S2E AT command example (Micropython)"
url: "https://maker.wiznet.io/Grace_Koo/projects/w55rp20-s2e-at-command-example-micropython/"
markdown_url: "https://maker.wiznet.io/Grace_Koo/projects/w55rp20-s2e-at-command-example-micropython/md"
type: "WCC: WIZnet Created Content"
author: "Grace"
author_url: "https://maker.wiznet.io/Grace_Koo/"
original_author: "Grace Koo"
published: "2026-01-30"
language: "en"
tags: ["wow-contest-ref"]
hardware: ["WIZnet W55RP20"]
likes: 0
views: 718
comments: 0
source: "WIZnet Makers (https://maker.wiznet.io/)"
---

# W55RP20-S2E AT command example (Micropython)

> This program is an example that sends AT commands to the W55RP20 S2E board via UART or SPI interface using MicroPython on a Raspberry Pi Pico (Master).

Original author: Grace Koo

## Components

- **WIZnet W55RP20** x 1 ([docs](https://wiznet.io/products/ionic-chips/w55rp20))
- Software: **MicroPython** ([docs](http://micropython.org/))

## Documents and links

- [GitHub : W55RP20-S2E_master_Micropython](https://github.com/WIZnet-ioNIC/WoW-io-Design-Contest/tree/main/MicroPython) (code)

## Article

## How to AT Command Example (MicroPython)

This program is an example that sends AT commands to the W55RP20 S2E board via UART or SPI interface using MicroPython on a Raspberry Pi Pico (Host). It demonstrates how to configure the module interactively through a shell-like interface.

## Step 1: Prepare software

The following software is required to run and test the MicroPython example.

- [Thonny](https://thonny.org/) : An integrated development environment for MicroPython. used to write, upload, and run code.

- [Hercules](https://www.hw-group.com/software/hercules-setup-utility)

## Step 2: Prepare hardware

1. Connect GPIO13 according to the selected UART/SPI mode of the W55RP20 EVB Pico, as illustrated below.

| GPIO13 Pin | Desc |
| --- | --- |
| LOW(GND) | UART mode (default) |
| HIGH(3.3V) | SPI mode |

2. Connect the Raspberry Pi Pico and the W55RP20 EVB Pico using jumper wires as shown below, depending on the selected UART/SPI mode.

- Important Note on Mode Switching: In this example setup, GPIO 13 of the W55RP20 EVB Pico is physically connected to GPIO 13 of the Raspberry Pi Pico. The Host Pico sets the mode (High/Low) automatically based on the software configuration.

- If you change the **`**MODE**`** in the code (e.g., UART ↔ SPI): You MUST reset both boards (Raspberry Pi Pico and W55RP20 EVB Pico) to ensure the mode is switched and recognized correctly.

If UART mode :

| Raspberry Pi Pico | W55RP20 EVB Pico |
| --- | --- |
| GPIO4 (UART_TX) | GPIO5 (UART_RX) |
| GPIO5 (UART_RX) | GPIO4 (UART_TX) |
| GPIO13 (MODE_SEL) | GPIO13 (MODE_SEL) |
| GND | GND |

If SPI mode :

| Raspberry Pi Pico(Master) | W55RP20 EVB Pico(Slave) |
| --- | --- |
| GPIO2 (SPI_CLK) | GPIO2 (SPI_CLK) |
| GPIO3 (SPI_TX) | GPIO4 (SPI_RX) |
| GPIO4 (SPI_RX) | GPIO3 (SPI_TX) |
| GPIO5 (SPI_CS) | GPIO5 (SPI_CS) |
| GPIO26 (SPI_INT) | GPIO26 (SPI_INT) |
| GPIO13 (MODE_SEL) | GPIO13 (MODE_SEL) |
| GND | GND |

3. Connect the Raspberry Pi Pico to your PC (desktop or laptop) using a 5-pin Micro USB cable.

4. Connect the W55RP20 EVB Pico to your PC (desktop or laptop) using a USB Type-C cable.

## Step 3: Setup AT Command Example

- Raspberry Pi Pico (Master) : [Getting started with Raspberry Pi Pico (MicroPython)](https://www.raspberrypi.com/documentation/microcontrollers/micropython.html)

Please refer to the link below to install the MicroPython firmware on the Raspberry Pi Pico.

- **W55RP20 EVB Pico : **[Getting started with W55RP20 EVB Pico](https://docs.wiznet.io/Product/Chip/MCU/Pre-programmed-MCU/W55RP20-S2E/w55rp20-evb-pico-s2e)

Please refer to the link below for instructions on how to use the W55RP20 S2E.

## Step 4: Upload Code

- **Raspberry Pi Pico**

Open Thonny IDE and connect to the Raspberry Pi Pico. Upload the following driver and example files to the Pico's storage.

![](https://maker.wiznet.io/upload/ckeditor5/408384515%5F1769791777%2Epng)

*PICO's storage*

Required Files:

1. `w55rp20_s2e_uart.py` (Required for UART mode)

2. `w55rp20_s2e_spi.py` (Required for SPI mode)

3. `01_at_cmd_tester.py` (Main example code)

Open `01_at_cmd_tester.py` and modify the `MODE` variable at the top of the code to match your hardware connection.

```c
# Configuration
MODE = "uart"   # Set to "spi" or "uart"
```

- **W55RP20 EVB Pico**

Following Step 3 in the Getting Started Guide, program the W55RP20 EVB Pico with the UF2 file and write the MAC address to complete the setup.

## Step 5: Run

For detailed information about the AT commands supported by the W55RP20 S2E, please refer to the document below.

- [W55RP20 S2E AT command Manual](https://docs.wiznet.io/Product/Chip/MCU/Pre-programmed-MCU/W55RP20-S2E/command-manual-en)

Run the `01_at_cmd_tester.py` script in Thonny (press F5). The shell will act as an interactive terminal for sending AT commands.

![](https://maker.wiznet.io/upload/ckeditor5/408384515%5F1769792047%2Epng)

#### Step 5.1: UART mode

When the example is successfully running in UART mode, the Host will automatically send `+++` to enter AT Command Mode. You will see the following output in the Thonny Shell:

![](https://maker.wiznet.io/upload/ckeditor5/408384515%5F1769792272%2Epng)

```python
=== W55RP20 AT Command Tester (UART) ===
[UART] Attempting to enter AT mode (Wait 1s -> +++ -> Wait 1s)...
[UART] Entry signal sent. Ready for commands.

[Usage]
 - Input: MC (Parses as CMD='MC', Param='') -> [GET]
 - Input: OP1 (Parses as CMD='OP', Param='1') -> [SET]
 - Help: ? or help
 - Exit: exit or quit
----------------------------------------
AT>
```

Testing Examples:

1.Enter `HELP` or `?` to display usage instructions for AT commands.

![](https://maker.wiznet.io/upload/ckeditor5/408384515%5F1769792383%2Epng)

2. Enter the `LI` command to get the current Local IP address.

![](https://maker.wiznet.io/upload/ckeditor5/408384515%5F1769792447%2Epng)

3. Enter `LI 192.168.11.32` to set a new Local IP address.

![](https://maker.wiznet.io/upload/ckeditor5/408384515%5F1769792600%2Epng)

4. Enter the `SV` command to save the settings to flash memory.

![](https://maker.wiznet.io/upload/ckeditor5/408384515%5F1769792564%2Epng)

5. Enter the `RT` command to reboot the module and apply the change

![](https://maker.wiznet.io/upload/ckeditor5/408384515%5F1769792652%2Epng)

![](https://maker.wiznet.io/upload/ckeditor5/408384515%5F1769792696%2Epng)

*W55RP20-S2E debug log*

When you perform a search using the WIZnet Config Tool, you can confirm that the Local IP address of the W55RP20 S2E has been changed.

![](https://maker.wiznet.io/upload/ckeditor5/408384515%5F1769792843%2Epng)

#### Step 5.2: SPI mode

When running in SPI mode, the example immediately establishes communication.

![](https://maker.wiznet.io/upload/ckeditor5/408384515%5F1769792985%2Epng)

Testing Examples:

1.Enter the `LI` command to get the current Local IP address.

![](https://maker.wiznet.io/upload/ckeditor5/408384515%5F1769793136%2Epng)

2. Enter `LI 192.168.11.15` to set a new Local IP address.

![](https://maker.wiznet.io/upload/ckeditor5/408384515%5F1769793175%2Epng)

3. Enter `SV` to save the configuration.

![](https://maker.wiznet.io/upload/ckeditor5/408384515%5F1769793206%2Epng)

![](https://maker.wiznet.io/upload/ckeditor5/408384515%5F1769793221%2Epng)

*W55RP20-S2E debug log*

After saving and rebooting, you can verify the new Local IP address (192.168.11.15) by searching for the device using the WIZnet Config Tool.

![](https://maker.wiznet.io/upload/ckeditor5/408384515%5F1769793271%2Epng)

---

Source: https://maker.wiznet.io/Grace_Koo/projects/w55rp20-s2e-at-command-example-micropython/