RTL8711 to SPI Flash connection and checking of Device Signature

RTL8711_SPI-Flash-ID.ino

#include <SPI.h>
#include "PinNames.h"
// 11 - GPIOC_2 - SPI0_MOSI = Connected to Chip SPI MOSI
// 12 - GPIOC_3 - SPI0_MISO = Connected to Chip SPI MISO
// 13 - GPIOC_1 - SPI0_CLK  = Connected to Chip SPI SCK
//      GPIOC_4 - SPI0_CS1  = Connected to Chip SPI CS
#define CS PC_4

SPISettings settings = SPISettings(20000000, MSBFIRST, SPI_MODE0);
void setup() {
  Serial.begin(9600); 
  pinMode(CS,OUTPUT);
  digitalWrite(CS, HIGH);  
  SPI.begin();  
  Serial.println(F("Ready!"));
}

void loop() {
  Serial.println ();
  Serial.println (F("SPI Signature Read"));
  
  digitalWrite(CS, LOW);
  SPI.beginTransaction(settings);
  SPI.transfer(0x9F);
  SPI.transfer(0x00);
  Serial.println(SPI.transfer(0x00),HEX);
  Serial.println(SPI.transfer(0x00),HEX);
  SPI.endTransaction();
  digitalWrite(CS, HIGH);

  digitalWrite(CS, LOW);
  SPI.beginTransaction(settings);
  SPI.transfer(0x90);
  SPI.transfer(0x00);
  SPI.transfer(0x00);
  SPI.transfer(0x00);
  Serial.println(SPI.transfer(0x00),HEX);
  Serial.println(SPI.transfer(0x00),HEX);
  SPI.endTransaction();
  digitalWrite(CS, HIGH);
  
  Serial.println();
  Serial.println(F("Done."));
  delay(1000);
}