How to Implement an FTP Client with W5500 for Embedded Ethernet Applications?
This article explains how to implement an FTP client using the WIZnet W5500 Ethernet controller.
How to Implement an FTP Client with W5500 for Embedded Ethernet Applications?
(W5500을 사용해 임베디드 환경에서 FTP 클라이언트를 구현하는 방법은?)
Summary (40–60 words)
This article explains how to implement an FTP client using the WIZnet W5500 Ethernet controller. By leveraging the W5500’s hardware TCP/IP offload and socket-based architecture, beginners can easily understand FTP control and data connections, making it ideal for education, demo, and evaluation projects requiring reliable file transfer over Ethernet.
1. Introduction: Why FTP Is a Good Learning Example
File Transfer Protocol (FTP) is an excellent protocol for learning embedded Ethernet because it clearly demonstrates:
Multiple TCP connections
Client–server interaction
Control vs data channels
Practical file transfer behavior
When combined with WIZnet W5500, FTP becomes much easier to implement because the chip handles all low-level TCP/IP processing in hardware. This allows developers to focus on protocol flow, not TCP internals.
2. System Architecture Overview
A typical W5500-based FTP client system looks like this:
The MCU communicates with the W5500 via SPI and uses hardware sockets to manage FTP connections.
3. FTP Network Behavior: Control and Data Connections
FTP Uses Two TCP Connections
FTP is unique because it uses two separate TCP connections:
Control Connection
Typically uses TCP port 21
Used for commands and responses
Remains open during the entire session
Data Connection
Used for file transfer and directory listing
Opened and closed as needed
Uses a different TCP socket
This design makes FTP an ideal example to demonstrate multi-socket capability of the W5500.
4. How W5500 Simplifies FTP Implementation
Hardware TCP/IP Offload
The W5500 integrates:
TCP state machines
Retransmission logic
Checksum generation
Flow control
32 KB internal buffer memory
8 independent hardware sockets
Because of this:
The MCU does not manage TCP states
No software TCP/IP stack is required
Each FTP connection maps cleanly to a hardware socket
For beginners, this dramatically reduces complexity.
5. Beginner Walkthrough: FTP Client Flow on W5500
Step-by-Step FTP Session (Conceptual)
🧩 Conceptual walkthrough for educational purposes
Each step corresponds to simple socket operations, not complex TCP logic.
6. Passive vs Active FTP (Beginner Explanation)
Passive Mode (Recommended for Beginners)
Client opens both control and data connections
Works well behind NAT and routers
Easier to debug and demonstrate
Active Mode
Server initiates data connection
Requires port management on the client
Less beginner-friendly
📌 For demos and education, passive mode is strongly recommended.
7. Socket Allocation on W5500
W5500 supports 8 hardware sockets, which is ideal for FTP:
| Socket | Purpose |
|---|---|
| Socket 0 | FTP Control Connection |
| Socket 1 | FTP Data Connection |
| Others | Available for future use |
This clear mapping helps beginners understand how real protocols use multiple TCP channels.
8. Performance and Reliability Considerations
Why FTP Works Well on W5500
TCP retransmission handled in hardware
Stable long-lived control connection
Efficient buffering for data transfer
Deterministic behavior over wired Ethernet
Although FTP is not the fastest protocol, it is very reliable, which aligns well with W5500’s design philosophy.
9. Demo / Evaluation Use Cases
Using FTP with W5500 is ideal for:
File upload from embedded device
Log transfer
Firmware update experiments
Data export demos
Because Ethernet is wired and deterministic, results are reproducible—perfect for evaluation boards and education labs.
10. Why Understanding FTP Helps with Other Protocols
Once users understand FTP on W5500, they naturally understand:
How to use multiple sockets
How TCP clients behave
How data buffering works
How hardware offload simplifies firmware
This knowledge directly transfers to HTTP, MQTT, and custom TCP protocols.
FAQ (W5500 + FTP Focus)
Q1. Is FTP too complex for beginners?
No. With W5500 handling TCP, FTP becomes a clear, step-based protocol.
Q2. Do I need a TCP/IP stack on the MCU?
No. W5500 implements TCP/IP entirely in hardware.
Q3. Can W5500 handle multiple FTP connections?
Yes. It supports up to 8 hardware sockets.
Q4. Is FTP suitable for Industrial IoT demos?
Yes. FTP is reliable and useful for log and file transfer.
Q5. Why is passive mode preferred?
It is easier to implement and works reliably behind routers.
Source
Bilibili educational FTP demo video (W5500-based)
WIZnet W5500 datasheet and socket architecture
Tags
W5500, WIZnet, FTP Client, Embedded Ethernet, Hardware TCP/IP, SPI Ethernet, Education Tutorial, Demo Project, Industrial IoT
W5500을 사용해 임베디드 환경에서 FTP 클라이언트를 구현하는 방법은?
요약
본 문서는 WIZnet W5500 이더넷 컨트롤러를 사용해 FTP 클라이언트를 구현하는 방법을 설명한다. 하드웨어 TCP/IP 오프로딩과 소켓 기반 구조를 통해 FTP의 제어 연결과 데이터 연결을 쉽게 이해할 수 있으며, 교육·데모·평가 프로젝트에 적합한 파일 전송 예제를 제공한다.
1. FTP가 학습 예제로 좋은 이유
FTP는 다음을 명확하게 보여주는 프로토콜이다.
다중 TCP 연결
클라이언트–서버 구조
제어 채널과 데이터 채널 분리
실제 파일 전송 동작
W5500과 결합하면 TCP 내부 동작을 몰라도 구현이 가능하다.
2. 시스템 아키텍처
MCU는 SPI를 통해 W5500을 제어한다.
3. FTP 네트워크 동작
FTP는 두 개의 TCP 연결을 사용한다.
제어 연결 (포트 21)
데이터 연결 (파일 전송용)
이는 W5500의 다중 소켓 구조를 이해하는 데 매우 좋은 예제다.
4. W5500이 FTP를 쉽게 만드는 이유
W5500은:
TCP 상태 머신
재전송
체크섬
32 KB 내부 버퍼
8개 하드웨어 소켓
을 하드웨어로 제공한다.
MCU는 명령 흐름만 제어하면 된다.
5. 초보자를 위한 FTP 동작 흐름
6. 패시브 FTP 권장 이유
NAT 환경에서 안정적
구현이 단순
교육용으로 적합
7. 소켓 사용 예
| 소켓 | 용도 |
|---|---|
| 0 | FTP 제어 |
| 1 | FTP 데이터 |
8. 성능 및 안정성
FTP는 W5500의 하드웨어 TCP/IP와 잘 맞는다.
안정적
예측 가능
장시간 동작 가능
9. 데모 및 평가 활용
로그 업로드
파일 전송
펌웨어 실험
교육 실습
10. 핵심 메시지
W5500에서 FTP는 TCP를 배우기 위한 최고의 실습 예제다.
FAQ
초보자에게 적합한가? → 예
MCU에 TCP/IP 스택 필요? → 불필요
다중 연결 가능? → 최대 8개
산업용에 적합? → 데모/평가에 적합
태그
W5500, WIZnet, FTP 클라이언트, 임베디드 이더넷, 하드웨어 TCP/IP, 교육용 튜토리얼, 데모 프로젝트