Arduino Event driven Ethernet library for W5100

This library is to facilitate your usage of W5100S-EVB-Pico board with the onboard Wiznet W5100S chip, using [**Arduino-mbed RP2040** core](https://github.com/arduino/ArduinoCore-mbed)

In case you are looking for an event driven approach of receiving Ethernet data/status, rather than the traditional polling method, this library may be one of choices for you.

Events to be dispatched to: void (*EthernetEventCallback)(uint8_t ir, uint8_t ir2, uint8_t slir);

1. Interrupt Register (IR)

     EthernetEventApi::Ir::CONFLICT

     EthernetEventApi::Ir::UNREACH

     EthernetEventApi::Ir::PPPTERM

   note: NO Sn_INT events in EthernetEventCallback. User should use Sn_IR in SocketEventCallback

2. Interrupt Register 2 (IR2)

     EthernetEventApi::Ir2::WOL

3. SOCKET-less Interrupt Register (SLIR)

     EthernetEventApi::Slir::TIMEOUT

     EthernetEventApi::Slir::ARP

     EthernetEventApi::Slir::PING

Events to be dispatched to: void (*SocketEventCallback)(uint8_t sn_ir);

1. SOCKET n Interrupt Register (Sn_IR)

    SnIR::SEND_OK

    SnIR::TIMEOUT

    SnIR::RECV

    SnIR::DISCON

    SnIR::CON

### User's Code comparison:

#### Using [EventEthernet](https://github.com/teamprof/arduino-eventethernet)

############################################################################

#include <EventEthernet.h>

void setup() {

  Ethernet.init(17, 21); // W5100S-EVB-Pico: nCS pin = GPIO17, Intn pin = GPIO21

  while (Ethernet.begin(mac, ir, ir2, slir, onEthernetEvent) == 0)

  {

    LOG_DEBUG("Failed to configure Ethernet using DHCP");

    delay(1000);

  }

}

############################################################################

#### Using original [WIZnet-ArduinoEthernet](https://github.com/WIZnet-ArduinoEthernet/Ethernet)

############################################################################

#include <Ethernet.h>

//#include <EventEthernet.h> // note: you can use EventEthernet lib on existing code with polling method

void setup() {

  Ethernet.init(17); // W5100S-EVB-Pico: nCS pin = GPIO17

  while (Ethernet.begin(mac) == 0)

  {

    LOG_DEBUG("Failed to configure Ethernet using DHCP");

    delay(1000);

  }

}