Serial Flash

#include <SPI.h>  

// Define the pin connections for the external SPI Flash chip
#define FLASH_CS   5   // Chip Select (CS) pin
#define FLASH_MISO 4   // Master In Slave Out (MISO) pin
#define FLASH_MOSI 7   // Master Out Slave In (MOSI) pin
#define FLASH_CLK  6   // Clock (SCK) pin

// Create an SPI object for FSPI (ESP32-C3 supports FSPI hardware bus)
SPIClass SPI1(FSPI);

void setup() {
  Serial.begin(115200);
  delay(1000);

  Serial.println("ESP32-C3 SPI Flash Test");

  pinMode(FLASH_CS, OUTPUT);
  digitalWrite(FLASH_CS, HIGH);

  SPI1.begin(FLASH_CLK, FLASH_MISO, FLASH_MOSI, FLASH_CS);
  SPI1.beginTransaction(SPISettings(1000000, MSBFIRST, SPI_MODE0));

  // Read JEDEC ID
  readJEDEC();

  // Write and Read Test Data
  writeData(0x000000, "Hello Flash!");
  delay(100);
  readData(0x000000, 12);
}

void loop() {
  // Nothing here
}

// ---------------- JEDEC READ ----------------
void readJEDEC() {
  digitalWrite(FLASH_CS, LOW);

  SPI1.transfer(0x9F);

  byte mfg  = SPI1.transfer(0x00);
  byte type = SPI1.transfer(0x00);
  byte size = SPI1.transfer(0x00);

  digitalWrite(FLASH_CS, HIGH);

  Serial.print("Manufacturer ID: 0x");
  Serial.println(mfg, HEX);
  Serial.print("Memory Type: 0x");
  Serial.println(type, HEX);
  Serial.print("Memory Size: 0x");
  Serial.println(size, HEX);
}

// ---------------- WRITE ENABLE ----------------
void writeEnable() {
  digitalWrite(FLASH_CS, LOW);
  SPI1.transfer(0x06);
  digitalWrite(FLASH_CS, HIGH);
}

// ---------------- WRITE DATA ----------------
void writeData(uint32_t address, const char* data) {
  writeEnable();

  digitalWrite(FLASH_CS, LOW);

  SPI1.transfer(0x02);  // Page Program

  SPI1.transfer((address >> 16) & 0xFF);
  SPI1.transfer((address >> 8) & 0xFF);
  SPI1.transfer(address & 0xFF);

  while (*data) {
    SPI1.transfer(*data++);
  }

  digitalWrite(FLASH_CS, HIGH);
  delay(10);
}

// ---------------- READ DATA ----------------
void readData(uint32_t address, int length) {
  digitalWrite(FLASH_CS, LOW);

  SPI1.transfer(0x03);

  SPI1.transfer((address >> 16) & 0xFF);
  SPI1.transfer((address >> 8) & 0xFF);
  SPI1.transfer(address & 0xFF);

  Serial.print("Data Read: ");

  for (int i = 0; i < length; i++) {
    char c = SPI1.transfer(0x00);
    Serial.print(c);
  }

  digitalWrite(FLASH_CS, HIGH);
  Serial.println();
}