---
title: "W55RP20 - What is RP2040 GPIO 17 internally tied to"
url: "https://maker.wiznet.io/forum/15999"
markdown_url: "https://maker.wiznet.io/forum/15999/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "jhinkle"
created: "2026-03-05T02:52:15+09:00"
last_activity: "2026-03-12T09:50:32+09:00"
language: "en"
tags: ["W55RP20"]
views: 5
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# W55RP20 - What is RP2040 GPIO 17 internally tied to

## Question

Asked by jhinkle on 2026-03-05 in Ethernet Chips.

I am writing NON-Sdk code for this device.

The documentation states: "However, GPIO17, GPIO20, GPIO21, GPIO22, GPIO23, GPIO24, and GPIO25 are not accessible due to the connections inside the board."

I have found connections for GPIO20-25, but not 17.

GPIO20-25 interface with the W5500 SPI.

Nowhere does documentation or drawings identify the GPIO17 internal connection.

Since the RP2040 code must initialize the stated GPIO - need to identify what GPIO 17 is internally connected to so the that RP2040 code can properly control it.

Can someone please provide.

Thanks.

## Replies

### Reply 1 by Grace_Koo, 2026-03-12

Hello jhinkle.

I apologize for the delayed response.

After checking internally, we confirmed that GPIO17 is not connected to any internal function or device on the board.

Unlike GPIO20–GPIO25, which are used for the W5500 SPI interface, GPIO17 is simply not exposed as an external pin due to pin availability limitations.

So, there does not appear to be any special internal connection that needs to be considered for GPIO17. It should be fine to initialize it in your RP2040 code.

Thank you.

---

Source: https://maker.wiznet.io/forum/15999