Various types of memory and swap types, what leads to their presence?

[carlosdelfino]

I am studying the architecture of the STM32H7 family, and according to the AN there are various types of memory, DRAM, SDRAM, NOR/PSRAM, NAND in addition to the swap between SDRAM and NOR/PSRAM.

What is the reason for such diversity and what benefits does this bring to the developer and the system?

[ELABI.1 · Accepted solution]

Hi @carlosdelfino 

The diversity of memory types offers flexibility and allows the system to be optimized according to the needs.

Here is an explanation for each type of memory:

DRAM (Dynamic Random-Access Memory)

• Characteristics: Volatile memory, requires periodic refreshing.
• Advantages:
  • DRAM can store a large amount of data in a relatively small physical space (high density).
  • Generally cheaper per bit compared to other types of memory.
  • Ideal for applications requiring large data buffers, such as video processing.

SDRAM (Synchronous Dynamic Random-Access Memory)

• Characteristics: Synchronized with the system clock, volatile memory.
• Advantages:
  • Faster access times due to synchronization with the system clock.
  • Suitable for applications requiring high-speed data transfers, such as graphics and multimedia.

NOR Flash

• Characteristics: Non-volatile memory.
• Advantages:
  • Retains data without power, suitable for firmware storage.
  • Allows random access to data, making it ideal for code execution.

PSRAM (Pseudo-Static Random-Access Memory)

• Characteristics: Volatile memory.
• Advantages:
  • Combines characteristics of DRAM and SRAM: Offers the density of DRAM with the ease of use of SRAM.
  • Simplifies design compared to DRAM (No Refresh Needed).

NAND Flash

• Characteristics: Non-volatile memory, block-oriented access.
• Advantages:
  • Can store large amounts of data, suitable for mass storage (High Density).
  • Lower cost per bit compared to NOR Flash.
  • Ideal for applications requiring significant data storage, such as file systems.

The Utility of Swapping between SDRAM and NOR/PSRAM 

Swapping can be used to optimize memory management and improve system performance.

Here is an explanation of this concept:

1. Performance Optimization

   • Allows leveraging the specific advantages of each type of memory. For example, SDRAM offers high capacity and speed, while NOR Flash and PSRAM offer non-volatility and ease of use. By using swapping, the system can move data between these memories based on performance and storage needs.

2. Efficient Memory Management

   • Enables efficient memory management by using SDRAM for operations requiring quick access and NOR Flash or PSRAM for storing less frequently used or critical data. This frees up SDRAM for memory-intensive tasks while preserving important data in non-volatile memory.

3. Improved Reliability

   • Critical data can be stored in NOR Flash, which is non-volatile and reliable, while temporary or less critical data can be stored in SDRAM or PSRAM. This improves system reliability by ensuring that important data is not lost in case of a power failure.

Thank you.

ELABI.1

[carlosdelfino]

Thank you, your explanation was very helpful.