WIZ550io and Arduino Pro Micro

Hi Guys,

I am trying to run WebServer example on Arduino Pro Micro (bit.ly/1iEC9R6).

Unfortunately, there is no SS pin on Pro Micro, so I’ve changed the main Arduino Ethernet library header file (/usr/share/arduino/libraries/Ethernet/utility/w5100.h, line 334) and redefine the SS pin as follows:

 #elif defined(__AVR_ATmega32U4__)
  //inline static void initSS()    { DDRB  |=  _BV(6); };
  //inline static void setSS()     { PORTB &= ~_BV(6); };
  //inline static void resetSS()   { PORTB |=  _BV(6); };

  inline static void initSS()    { pinMode(PRO_MICRO_SS, OUTPUT); \
                                   digitalWrite(PRO_MICRO_SS, HIGH); };
  inline static void setSS()     { digitalWrite(PRO_MICRO_SS, LOW); };
  inline static void resetSS()   { digitalWrite(PRO_MICRO_SS, HIGH); };

and using pin 10 on Pro Micro as Slave Select pin:

#define PRO_MICRO_SS 10

Unfortunately, it is not working.
The printed IP address over serial port is

Any idea what is the problem?

I’m using two AAA batteries to power up WIZ550io separately. Attached pins are:
Pro Micro → WIZ550io
10 → SS (J1 - pin 6)
16 → MOSI (J1 - pin 3)
14 → MISO (J1 - pin 4)
15 → SCLK (J1 - pin 5)

The RSTn pin (J2- pin 3) is not connected.


WIZ550io have the default network configuration as
For this, WIZ550io have a tiny mcu confiures the default network into W5500 during 500ms after reset.

You’d better try to access WIZ550io after over 500ms.

Thank you.

Thanks for the response.

My home router subnet is, so it might be the problem.