---
title: "[WIZnet-PICO-C example] UDP Server Example, debug print missing"
url: "https://maker.wiznet.io/forum/15746"
markdown_url: "https://maker.wiznet.io/forum/15746/md"
type: "Forum topic"
category: "General"
author: "Aimee0"
created: "2025-06-05T13:16:44+09:00"
last_activity: "2025-06-25T09:12:30+09:00"
language: "en"
views: 8
replies: 2
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# [WIZnet-PICO-C example] UDP Server Example, debug print missing

## Question

Asked by Aimee0 on 2025-06-05 in General.

### **🔧 UDP Server Example, debug print missing**

<https://github.com/aimee0000/TSG_maker/blob/main/WIZnet_PICO_C_Troubleshooting.md#-udp-server-example-debug-print-missing>

Problem Phenomenon (The issue):

- The user is not seeing the expected debug print statements on the serial terminal when running the `w5x00_udp_server.c` example on a W55RP20-EVB-PICO board, despite enabling the `_LOOPBACK_DEBUG_` macro.

Cause (The cause of the issue):

- The `_LOOPBACK_DEBUG_` macro is intended to print messages only when there is a send or receive error, not for mirroring received UDP packets to the UART port as the user assumed.

Solution (Concrete code changes, configuration changes, step-by-step actions, etc., that actually solved the problem):

- To change the UART or USB message output settings, modify the options in the `CMakeLists.txt` file located at `WIZnet-PICO-C\examples\udp\udp_server\` by setting the desired output to 1:

```
pico_enable_stdio_usb(${TARGET_NAME} 1)
pico_enable_stdio_uart(${TARGET_NAME} 0)
```

- This configuration enables USB output and disables UART output. Adjust these settings according to the desired output method.

[View GitHub Issue](https://github.com/WIZnet-ioNIC/WIZnet-PICO-C/issues/10)

## Replies

### Reply 1 by norajohnson, 2025-06-21

I'm using a wiznet W6100 EVB Pico board and it should send and receive data on a multicast address however I'm not finding anythig that works correctly. These sections will guide you through a series of steps from configuring development environment to running ethernet examples using the WIZ net's ethernet ...Lots of example Ethernet projects available [monkey type](https://monkey-type.net/) and just as easy to develop for as the STM32F401. Also,. > Due to the complexity of the signalling involved with ...This is the documentation for the Raspberry Pi Pico Arduino core, Arduino-Pico. Arduino-Pico is a community port of. Arduino to the RP2040 (Raspberry Pi ...

### Reply 2 by Aimee0, 2025-06-25 (in reply to reply 1)

If you enable `set(BOARD_NAME W6100_EVB_PICO)` in the example from the following link, you will be able to run UDP multicast on the W6100-EVB-Pico.

<https://github.com/WIZnet-ioNIC/WIZnet-PICO-C/tree/main/examples/udp_multicast/udp_multicast_receiver>

---

Source: https://maker.wiznet.io/forum/15746