#include <SPI.h>

#define CS_1 9
#define CS_2 10

char buffer_1[] = "SPI 1! ";
char buffer_2[] = "SPI 2! ";

void testSPI(uint8_t cs_pin, char buf[]) {
  digitalWrite(cs_pin, LOW);
  SPI.begin();
  SPI.transfer(buf, strlen(buf));
  SPI.end();
  digitalWrite(cs_pin, HIGH);

  Serial.print("Data received from SPI device with CS pin ");
  Serial.print(cs_pin);
  Serial.println(":");
  Serial.println(buf);
}

void setup() {
  Serial.begin(115200);
  pinMode(CS_1, OUTPUT);
  pinMode(CS_2, OUTPUT);
  testSPI(CS_1, buffer_1);
  testSPI(CS_2, buffer_2);
}

void loop() {
}