mapleSPIMaster

#include <SPI.h>
int ss=7;

 SPISettings settingsA(250000, MSBFIRST, SPI_MODE1);

void setup(){
  pinMode(ss, OUTPUT);
  SPI.begin();
  SPI.setBitOrder(MSBFIRST);
}

uint8_t c = 0;

void sendSPI() {
  SPI.beginTransaction(settingsA);
  digitalWrite(ss, LOW);
  SPI.transfer(c); // send value (0~255)
  digitalWrite(ss, HIGH);
  SPI.endTransaction();
}

void loop() {
    c++;
    if (c >=255) c = 0;
    sendSPI();
    delay(200);
}