Floats and structs sent from Arduino to Arduino over SPI

[GolamMostafa]

But, you have put the line in the setup() function of Master; as a result, the line has become an input line (with internal pull-up); whereas, the line should be an output line from Master's side (Fig-1, post #31). The line is totally missing in the setup() of the Slave. Then the question is: why the system is working -- it is working because you have excuted digitalWrite(SS, LOW); at the Master side. To me, this is a flaw though the system is working!

@J-M-L

void setup() {
  Serial.begin(115200);
  pinMode(SS, INPUT_PULLUP);  // Keep SS HIGH
  SPI.begin();
}