//Perform only when on pins are inputs (at powerup)
  bool testConnection() {
      //Read current polarity config
      const uint16_t old_value;
      if (!this->getPolarity16(old_value) {
        return false;
      }

      //Write constant to polarity register
      if (!this->setPolarity16(_connection_test_constant) {
        return false;
      }

      //Read current polarity config
      const uint16_t temp;
      if (!this->getPolarity16(temp) {
        return false;
      }

      //Write old config to polarity register
      if (!this->setPolarity16(old_value) {
        return false;
      }

      if (temp == _connection_test_constant) {
        return true;
      }

      return false;
  }

//Somewhere in the class private
const uint16_t _connection_test_constant = 0xAABB;

//any arbitrary value, but not 0 or 0xFFFF (on teensy an unconnected spi transfer will return 0, but I don't know about other platforms)