W5100S-L

The W5100S-L is a hardwired TCP/IP embedded Ethernet controller from WIZnet, designed to provide easy and reliable internet connectivity for embedded systems. As a 3-in-1 solution integrating a full hardware TCP/IP protocol stack, Ethernet MAC, and 10/100 Ethernet PHY, the W5100S offloads the entire network protocol processing from the host microcontroller, dramatically simplifying embedded Ethernet design.

Unlike software-based TCP/IP stacks that consume significant MCU resources and are vulnerable to network attacks, WIZnet’s patented hardwired TCP/IP technology implements the protocol stack entirely in hardware. This provides stable, deterministic network performance and inherent security against common network threats such as SYN flooding, IP spoofing, and protocol injection attacks. The supported protocols include TCP, UDP, ICMP, IGMPv1/v2, IPv4, ARP, and PPPoE.

The W5100S provides four independent hardware SOCKETs, each with configurable send/receive buffer sizes allocated from the 16KB internal shared memory. This enables multiple simultaneous network connections such as a web server, TCP data connection, and UDP broadcast all running concurrently.

Two host interface options are available: a high-speed SPI interface supporting up to 70MHz clock speed, and an 8-bit parallel system bus with 2 address lines for even higher throughput. The device’s I/O pins are 5V tolerant, simplifying interfacing with both 3.3V and 5V microcontrollers.

Additional features include Power Down mode for low power consumption, Wake-on-LAN over UDP for remote activation, SOCKET-less commands (ARP and PING) for basic network diagnostics without opening a socket, and integrated network status LED drivers. The W5100S is software-compatible with the earlier W5100, meaning existing application code can run without modification. The -L variant is packaged in a 48-pin LQFP measuring 7 x 7mm with 0.5mm pitch.

The W5100S operates as a network offload engine, handling all Ethernet and TCP/IP protocol processing in dedicated hardware, freeing the host microcontroller for application tasks. Here’s how it works:

1. Hardwired TCP/IP Stack: The core of the W5100S is WIZnet’s proprietary hardwired TCP/IP stack, implemented entirely in hardware logic. Unlike software TCP/IP stacks that run on the host MCU, this hardware implementation processes protocols at wire speed with deterministic latency. The stack handles TCP (including connection management, retransmission, windowing), UDP, ICMP (ping), IGMP (multicast), ARP (address resolution), and PPPoE without any host software intervention.

2. Hardware Sockets: The W5100S provides four independent hardware sockets (SOCKET 0-3). Each socket can be configured independently for TCP server, TCP client, UDP, MACRAW, or PPPoE mode. Each socket has its own set of registers and can be assigned a configurable portion of the 16KB internal memory for transmit and receive buffering. This allows up to four simultaneous network connections.

3. Memory Architecture: A 16KB block of dual-port RAM serves as shared TX/RX buffer memory across all sockets. The memory is divided between transmit and receive buffers, with each socket’s allocation programmable via register settings. The host MCU accesses this memory through indirect addressing (via read/write pointer registers) over either the SPI or parallel interface.

4. Ethernet PHY (Physical Layer): The integrated 10BaseT/100BaseTX PHY handles all physical layer functions including encoding/decoding, clock recovery, link detection, and auto-negotiation. Auto-negotiation automatically selects the highest performance common mode (10/100 Mbps, full/half duplex) between the W5100S and the connected network device. Auto-MDIX automatically corrects for straight-through vs. crossover cable connections.

5. Host Interface – SPI: The SPI interface operates in mode 0 or mode 3 with clock speeds up to 70MHz. Communication uses a simple protocol where the host sends an address phase followed by read/write data. This is the simplest interface requiring only 4 wires (SCLK, MOSI, MISO, /SCS) plus optional interrupt.

6. Host Interface – Parallel Bus: For higher performance, the 8-bit parallel bus interface uses two address lines (A0/A1) plus 8 data lines and control signals (/RD, /WR, /CS). This provides faster data transfer than SPI, suitable for high-throughput applications.

7. Power Management: The W5100S supports a Power Down mode that shuts down most internal circuitry to minimize power consumption. In this state, the device can be awakened via Wake-on-LAN (a special UDP packet) or by the host MCU toggling a control signal. Normal operation current is also optimized for low power dissipation.

Package: 48-pin LQFP (Low-profile Quad Flat Package). Body dimensions: 7mm x 7mm, 0.5mm lead pitch. -L suffix designates LQFP package (vs -Q for QFN). Lead-free, RoHS compliant.

• Serial-to-Ethernet Converters: Serial (UART/RS-232/RS-485) to Ethernet protocol converters used for connecting legacy serial devices to IP networks, including industrial device servers, MODBUS gateways, and remote equipment monitoring interfaces, where the hardwired TCP/IP stack guarantees reliable, deterministic performance without MCU overhead.
• IoT and Smart Home Devices: Network connectivity for smart home appliances, HVAC systems, security cameras, door locks, and energy management devices, where low cost, small footprint, and hardware TCP/IP security are essential for reliable and secure IoT node implementation.
• Industrial Automation: Ethernet connectivity for PLCs, remote I/O modules, industrial sensors, and factory floor equipment, supporting industrial Ethernet protocols and Modbus TCP, with the -40 degC to +85 degC industrial temperature range and robust hardware stack ensuring operation in harsh factory environments.
• Embedded Web Servers: Remote configuration and monitoring interfaces for embedded equipment, where the W5100S hosts a lightweight web server allowing users to access device status, update firmware, and change settings through a standard web browser.
• Arduino/Evaluation Shields and Modules: Ethernet shields for Arduino, Raspberry Pi Pico, and other development platforms, enabling hobbyists, students, and engineers to quickly add wired Ethernet connectivity to their projects using WIZnet’s well-documented ioLibrary_Driver software stack.
• POS Terminals and Payment Devices: Network connectivity for point-of-sale terminals, card readers, and payment processing equipment, where the hardware-offloaded TCP/IP stack reduces MCU load and provides the reliable connectivity required for financial transaction processing.
• Data Acquisition and Sensor Networks: Industrial data loggers, environmental monitoring systems, and distributed sensor networks that need to transmit collected data to a central server over Ethernet, with the 4 independent sockets supporting multiple simultaneous data streams or protocols.
• Security and Access Control Systems: Network connectivity for IP cameras, access control panels, intercom systems, and security alarm panels, where the stable hardware TCP/IP stack and resistance to network attacks provide enhanced reliability for security-critical applications.