SPI Flash

🧠 SPI Perfect 👍 Here's your English version, translated naturally for an undergraduate + practical level audience — exactly matching the tone and detail of the Korean version you liked.

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🧠 SPI Flash Command Structure (Based on Winbond W25Q Series)

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1️⃣ Basic SPI Transaction Structure

Each SPI command frame usually follows this sequence:

[CS LOW] → [Command] → [Address (optional)] → [Data (Read/Write)] → [CS HIGH]

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2️⃣ Common Commands (W25Q64 Example)

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3️⃣ Example Command Sequences

🧩 (1) Read JEDEC ID — 0x9F

Used to confirm the Flash’s manufacturer and device type.

Result:

• Manufacturer ID = 0xEF (Winbond)

• Memory Type = 0x40

• Capacity = 0x17 → 64 Mbit

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🧩 (2) Read Data — 0x03

Example waveform:

MOSI: [03 00 10 00]
MISO: [AA BB CC DD ...] ← Flash contents

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🧩 (3) Page Program — 0x02

You must enable writing before programming.

Step 1: Write Enable

CS LOW
0x06
CS HIGH

Step 2: Page Program

CS LOW
0x02
<Address 3 bytes>
<Data up to 256 bytes>
CS HIGH

Then poll the WIP (Write In Progress) bit via 0x05.

while(ReadStatus() & 0x01);  // Wait until WIP == 0

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🧩 (4) Read Status Register — 0x05

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🧩 (5) Sector Erase — 0x20

Then use 0x05 to check WIP bit until erase completes.

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4️⃣ MCU-Level Example Code

// Read Flash ID
CS_LOW();
SPI_Transfer(0x9F);
uint8_t mfg  = SPI_Transfer(0x00);
uint8_t type = SPI_Transfer(0x00);
uint8_t cap  = SPI_Transfer(0x00);
CS_HIGH();

printf("Flash ID: %02X %02X %02X\n", mfg, type, cap);

// Read Data
CS_LOW();
SPI_Transfer(0x03);                 // Read command
SPI_Transfer(0x00);                 // Addr[23:16]
SPI_Transfer(0x10);                 // Addr[15:8]
SPI_Transfer(0x00);                 // Addr[7:0]
for(int i = 0; i < 16; i++)
    buffer[i] = SPI_Transfer(0x00); // Dummy write to read data
CS_HIGH();

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5️⃣ Typical Operation Flow

1) 0x9F → Read JEDEC ID
   => EF 40 17

2) 0x06 → Write Enable
3) 0x20 + Address → Erase Sector
4) 0x02 + Address + Data → Page Program
5) 0x03 + Address → Read Data

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6️⃣ Example SPI Waveform (Logic Analyzer View)

CS:   ────────┐■■■■■■■■■■■■■■■■■┌────────────
SCLK:      ↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓
MOSI:  0x9F 00 00 00
MISO:       EF 40 17

→ This frame represents a “Read JEDEC ID” transaction.

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7️⃣ Summary Table

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💡 Key Takeaway

SPI Flash communication is command-driven and synchronous.
Each operation begins with pulling CS low,
followed by sending a command and address,
then exchanging data through MOSI/MISO lines.

Typical workflow:
Write Enable → Command → Status Check → Read/Write Data

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Would you like me to include the waveform timing diagram (with MOSI/MISO/SCLK transitions labeled) next?
It would visually explain how each byte shifts bit-by-bit — excellent for interviews or reports. Command Structure (Based on Winbond W25Q Series)

1️⃣ Basic SPI Transaction Structure

Each SPI command frame usually follows this sequence:

[CS LOW] → [Command] → [Address (optional)] → [Data (Read/Write)] → [CS HIGH]

---

2️⃣ Common Commands (W25Q64 Example)

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3️⃣ Example Command Sequences

🧩 (1) Read JEDEC ID — 0x9F

Used to confirm the Flash’s manufacturer and device type.

Result:

• Manufacturer ID = 0xEF (Winbond)

• Memory Type = 0x40

• Capacity = 0x17 → 64 Mbit

---

🧩 (2) Read Data — 0x03

Example waveform:

MOSI: [03 00 10 00]
MISO: [AA BB CC DD ...] ← Flash contents

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🧩 (3) Page Program — 0x02

You must enable writing before programming.

Step 1: Write Enable

CS LOW
0x06
CS HIGH

Step 2: Page Program

CS LOW
0x02
<Address 3 bytes>
<Data up to 256 bytes>
CS HIGH

Then poll the WIP (Write In Progress) bit via 0x05.

while(ReadStatus() & 0x01);  // Wait until WIP == 0

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🧩 (4) Read Status Register — 0x05

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🧩 (5) Sector Erase — 0x20

Then use 0x05 to check WIP bit until erase completes.

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4️⃣ MCU-Level Example Code

// Read Flash ID
CS_LOW();
SPI_Transfer(0x9F);
uint8_t mfg  = SPI_Transfer(0x00);
uint8_t type = SPI_Transfer(0x00);
uint8_t cap  = SPI_Transfer(0x00);
CS_HIGH();

printf("Flash ID: %02X %02X %02X\n", mfg, type, cap);

// Read Data
CS_LOW();
SPI_Transfer(0x03);                 // Read command
SPI_Transfer(0x00);                 // Addr[23:16]
SPI_Transfer(0x10);                 // Addr[15:8]
SPI_Transfer(0x00);                 // Addr[7:0]
for(int i = 0; i < 16; i++)
    buffer[i] = SPI_Transfer(0x00); // Dummy write to read data
CS_HIGH();

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5️⃣ Typical Operation Flow

1) 0x9F → Read JEDEC ID
   => EF 40 17

2) 0x06 → Write Enable
3) 0x20 + Address → Erase Sector
4) 0x02 + Address + Data → Page Program
5) 0x03 + Address → Read Data

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6️⃣ Example SPI Waveform (Logic Analyzer View)

CS:   ────────┐■■■■■■■■■■■■■■■■■┌────────────
SCLK:      ↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓
MOSI:  0x9F 00 00 00
MISO:       EF 40 17

→ This frame represents a “Read JEDEC ID” transaction.

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7️⃣ Summary Table

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💡 Key Takeaway

SPI Flash communication is command-driven and synchronous.
Each operation begins with pulling CS low,
followed by sending a command and address,
then exchanging data through MOSI/MISO lines.

Typical workflow:
Write Enable → Command → Status Check → Read/Write Data

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