QSPI (Quad Serial Peripheral Interface)
QSPI is an enhanced version of SPI that uses 4 bidirectional data lines (IO0-IO3) instead of 2, enabling 4x faster data transfer. Commonly used for high-speed Flash memory and storage devices.
📌 QSPI Key Features
- Multi-Mode Support: Standard SPI (1-bit), Dual SPI (2-bit), Quad SPI (4-bit)
- 4 Data Lines: IO0, IO1, IO2, IO3 - All bidirectional for maximum flexibility
- 4x Speed: Quad mode transfers 4 bits per clock cycle (4x faster than standard SPI)
- Same Control Signals: Uses standard CS (Chip Select) and SCK (Clock)
- MSB First: Data is transferred Most Significant Bit first (bit 15 → bit 0 for 16-bit data)
- Flash Memory: Primary use case is NOR Flash, NAND Flash, and other high-speed memory
- Backward Compatible: Can operate in standard SPI mode for compatibility
🔄 QSPI Timing Waveform
🔧 JSON Editor
📖 QSPI Transfer Modes
1️⃣
Standard SPI (1-bit): Uses only IO0 (MOSI) and IO1 (MISO), same as traditional SPI - 1 bit per clock cycle
2️⃣
Dual SPI (2-bit): Uses IO0 and IO1 bidirectionally - 2 bits per clock cycle (2x faster)
3️⃣
Quad SPI (4-bit): Uses all four lines (IO0-IO3) bidirectionally - 4 bits per clock cycle (4x faster)
🔌 QSPI Signal Lines
| Signal | Standard SPI Function | QSPI Function |
|---|---|---|
| CS | Chip Select | Chip Select (same) |
| SCK | Serial Clock | Serial Clock (same) |
| IO0 | MOSI (Master Out) | Bidirectional Data Bit 0 |
| IO1 | MISO (Master In) | Bidirectional Data Bit 1 |
| IO2 | WP# (Write Protect) | Bidirectional Data Bit 2 |
| IO3 | HOLD# (Hold) | Bidirectional Data Bit 3 |
⚡ Performance Comparison
Standard SPI
1 bit/cycle
100 MHz = 100 Mbps
Dual SPI
2 bits/cycle
100 MHz = 200 Mbps
Quad SPI
4 bits/cycle
100 MHz = 400 Mbps