flash
Nand Flash
- Raspberry Pi CM Module 4 - RMP-RPI-CM4-dat
Nor Flash
What is NOR Flash?
NOR flash is a type of non-volatile memory that allows random read access. It is commonly used for storing firmware and allows executing code directly from flash (XIP - Execute In Place).
Comparison Table
| Feature | Parallel NOR Flash | SPI NOR Flash (SPI Flash) |
|---|---|---|
| Interface | Parallel (8/16-bit bus) | Serial (SPI: MOSI, MISO, SCLK) |
| Speed | High (fast random access) | Lower (due to serial nature) |
| Pins Required | Many (20+ pins) | Few (4–6 pins) |
| Physical Size | Larger | Smaller |
| Cost | More expensive | Cheaper |
| Power Consumption | Higher | Lower |
| Read Access | Random access (byte-wise) | Page-based, sequential access |
| Write Access | Sector/page erase/write | Sector/page erase/write |
| XIP Support | Yes (native) | Limited or requires mapping |
| Use Cases | Boot code, firmware (MCUs, routers) | Microcontrollers, IoT, sensors |
| Typical Capacity | Up to 512 MB | Up to 2 GB |
Summary
- SPI Flash is a type of NOR Flash that uses a serial interface (SPI).
- SPI NOR Flash sacrifices speed and flexibility for lower cost, lower pin count, and small size.
- Parallel NOR Flash is better for code execution and high-speed access.