SPITest

SPITest.ino

#include <SPI.h>

void setup() {
  SPI.begin();
  Serial.begin(9600);
  SPI.setClockDivider(SPI_CLOCK_DIV2);

  while (!Serial)
    ;
  delay(5000);

  Serial.print("                            Plain SPI:     ");
  test_no_transaction();
  Serial.println();

#if defined(SPI_HAS_TRANSACTION)
  Serial.print("Transaction API (interrupts not used): (4) ");
  test_transaction_4x();
  Serial.println();
  Serial.print("Transaction API (interrupts not used): (2) ");
  test_transaction_2x();
  Serial.println();

  // Uncomment to check interrupt-based API
  SPI.usingInterrupt(0);

  // Uncomment to check event-based API
  //SPI.onBeginEvent(beginEvent);
  //SPI.onEndEvent(endEvent);

  Serial.print("Transaction API    (using interrupts): (4) ");
  test_transaction_4x();
  Serial.println();
  Serial.print("Transaction API    (using interrupts): (2) ");
  test_transaction_2x();
  Serial.println();
#endif
}

boolean interruptSave;

void beginEvent() {
  interruptSave = interruptsStatus();
  noInterrupts();
}

void endEvent() {
  if (interruptSave) interrupts();
}

void loop() {
}

void test_transaction_4x() {
  uint32_t start = millis();
  for (int i = 0; i < 30000; i++) {
    SPI.beginTransaction(SPI_CLOCK_8000000, MSBFIRST, SPI_MODE0);
    SPI.transfer(0xff);
    SPI.transfer(0xff);
    SPI.endTransaction();

    SPI.beginTransaction(SPI_CLOCK_8000000, MSBFIRST, SPI_MODE0);
    SPI.transfer(0xff);
    SPI.transfer(0xff);
    SPI.endTransaction();

    SPI.beginTransaction(SPI_CLOCK_8000000, MSBFIRST, SPI_MODE0);
    SPI.transfer(0xff);
    SPI.transfer(0xff);
    SPI.endTransaction();

    SPI.beginTransaction(SPI_CLOCK_8000000, MSBFIRST, SPI_MODE0);
    SPI.transfer(0xff);
    SPI.transfer(0xff);
    SPI.endTransaction();
  }
  uint32_t delta = millis() - start;
  float loopsPerSec = 1000.0 / delta * 30000.0;
  float throughput = loopsPerSec * 8 * 8;
  Serial.print(throughput);
}


void test_transaction_2x() {
  uint32_t start = millis();
  for (int i = 0; i < 30000; i++) {
    SPI.beginTransaction(SPI_CLOCK_8000000, MSBFIRST, SPI_MODE0);
    SPI.transfer(0xff);
    SPI.transfer(0xff);

    SPI.transfer(0xff);
    SPI.transfer(0xff);
    SPI.endTransaction();

    SPI.beginTransaction(SPI_CLOCK_8000000, MSBFIRST, SPI_MODE0);
    SPI.transfer(0xff);
    SPI.transfer(0xff);

    SPI.transfer(0xff);
    SPI.transfer(0xff);
    SPI.endTransaction();
  }
  uint32_t delta = millis() - start;
  float loopsPerSec = 1000.0 / delta * 30000.0;
  float throughput = loopsPerSec * 8 * 8;
  Serial.print(throughput);
}

void test_no_transaction() {
  uint32_t start = millis();
  for (int i = 0; i < 30000; i++) {
    SPI.transfer(0xff);
    SPI.transfer(0xff);

    SPI.transfer(0xff);
    SPI.transfer(0xff);

    SPI.transfer(0xff);
    SPI.transfer(0xff);

    SPI.transfer(0xff);
    SPI.transfer(0xff);
  }
  uint32_t delta = millis() - start;
  float loopsPerSec = 1000.0 / delta * 30000.0;
  float throughput = loopsPerSec * 8 * 8;
  Serial.print(throughput);
}