#include void setup() { Serial.begin(9600); while (!Serial); SPI.begin(); pinMode(10, OUTPUT); digitalWrite(10, LOW); // Select W5500 Serial.println("Testing SPI..."); byte response = SPI.transfer(0x00); // Send dummy byte and read response Serial.print("SPI Response: "); Serial.println(response, HEX); digitalWrite(10, HIGH); // Deselect W5500 } void loop() { }