HAL SRAM How to Use

group SRAM_How_To_Use

How to use the SRAM HAL module driver

The FMC SRAM main features :

This SRAM HAL driver is a generic driver which contains a set of APIs used to configure the FMC SRAM sub-banks to interface with SRAM, PSRAM and CRAM memories.

The FMC SRAM peripheral supports the following read and write access modes :

• SRAM memories :

  • Asynchronous read and asynchronous write with identical timing for both operations.

  • Asynchronous read and asynchronous write with distinct timing for each operation.

• PSRAM/CRAM memories :

  • Asynchronous read and asynchronous write with identical timing for both operations.

  • Asynchronous read and asynchronous write with distinct timing for each operation.

  • Synchronous read and synchronous write.

  • Synchronous read and asynchronous write.

  • Asynchronous read and synchronous write.

The FMC SRAM peripheral supports the write protection feature.

The SRAM HAL driver can be used as follows :

This module provides 5 different set of APIs that allows to :

• Initialize and de-initialize the logical FMC SRAM object ( hal_sram_handle_t), retrieve the associated SRAM peripheral instance, set and get region remap :

• Initialize the logical FMC SRAM object and associate it to a physical instance (sub-bank). This functionality is ensured by HAL_SRAM_Init() function.

• De-initialize the logical FMC SRAM object and disable the SRAM sub-bank. This functionality is ensured by HAL_SRAM_DeInit() function.

• Retrieve the SRAM instance by calling HAL_SRAM_GetInstance().

• At this stage, the mapping of FMC SRAM regions can be modified, if required, allowing to access the SRAM memory at two different address mappings by calling HAL_SRAM_SetRegionRemap().

• Retrieve the current memory region remap by calling HAL_SRAM_GetRegionRemap().

Configure the FMC SRAM to be ready to use and retrieve the current configuration :

• Configure the FMC SRAM through three steps by following the order below :

  • Step 1 (FMC configuration) : is the first step to perform once the HAL SRAM driver is initialized. This functionality is ensured by HAL_SRAM_SetConfig() function.

    At this stage, the SRAM is partially configured but not yet ready to use.

  • Step 2 (Memory configuration) : is the second step to perform once the FMC is configured. This functionality is ensured by one of these 5 functions depending on the external device access mode :

    • HAL_SRAM_SetConfigRdWrAsyncMemory() function to set the configuration for memories with asynchronous read and asynchronous write access mode. This API sets identical timing for both access.

    • HAL_SRAM_SetWrAsyncTimings() function to be called after HAL_SRAM_SetConfigRdWrAsyncMemory(), when memory with asynchronous read and asynchronous write access mode requires a different timing configuration for write transactions.

    • HAL_SRAM_SetConfigRdWrSyncMemory() function to set the configuration for memories with synchronous read and synchronous write access mode.

    • HAL_SRAM_SetConfigRdSyncWrAsyncMemory() function to set the configuration for memories with synchronous read and asynchronous write access mode.

    • HAL_SRAM_SetConfigRdAsyncWrSyncMemory() function to set the configuration for memories with asynchronous read and synchronous write access mode.

      At this stage, the SRAM is fully configured but not yet ready to use.

  • Step 3 (Memory enable/disable) : is the third step to perform once the SRAM is fully configured. This functionality is ensured by HAL_SRAM_EnableMemory() and HAL_SRAM_DisableMemory() functions.

    • HAL_SRAM_EnableMemory() : function to enable the SRAM sub-bank and make it accessible for read and write operations.

    • HAL_SRAM_DisableMemory() : function to disable the SRAM sub-bank which is useful when memory configuration adjustments are needed or to save power. The HAL_SRAM_EnableMemory() must be recalled to enable the memory and make it accessible.

      At this stage, the SRAM is fully configured, enabled and ready for use.

• Retrieve the current configuration through the following functions :

  • Retrieve the FMC configuration : This functionality is ensured by HAL_SRAM_GetConfig().

  • Retrieve the memory configuration : This functionality is ensured by one of these 5 functions depending on the external device access mode :

    • HAL_SRAM_GetConfigRdWrAsyncMemory() function to get the memory configuration for memories with asynchronous read and asynchronous write access mode.

    • HAL_SRAM_GetWrAsyncTimings() function to get the timing configuration for write operations, when the memory with asynchronous read and asynchronous write access mode has a different timing configuration for write transactions.

    • HAL_SRAM_GetConfigRdWrSyncMemory() function to get the memory configuration for memories with synchronous read and synchronous write access mode.

    • HAL_SRAM_GetConfigRdSyncWrAsyncMemory() function to get the memory configuration for memories with synchronous read and asynchronous write access mode.

    • HAL_SRAM_GetConfigRdAsyncWrSyncMemory() function to get the memory configuration for memories with asynchronous read and synchronous write access mode.

    • To identify the base address of the FMC SRAM memory region before performing any read or write operations, the region start address can be retrieved by calling HAL_SRAM_GetRegionBaseAddress().

Manage the FMC SRAM peripheral access when it is fully configured :

• Enable the FMC SRAM write protection (when disabled) to prevent any write access to the external device. This functionality is ensured by HAL_SRAM_EnableWriteProtection() function.

• Disable the FMC SRAM write protection (when enabled) to allow any write access to the external device. This functionality is ensured by HAL_SRAM_DisableWriteProtection() function.

• Retrieve the FMC SRAM sub-bank write protection state. This functionality is ensured by HAL_SRAM_IsEnabledWriteProtection() function.

Store and retrieve user data :

• Store user data pointer into the handle. This functionality is ensured by HAL_SRAM_SetUserData() function.

• Retrieve user data pointer from the handle. This functionality is ensured by HAL_SRAM_GetUserData() function.

Retrieve the HAL SRAM state and clock frequency :

• Retrieve the HAL SRAM state. This functionality is ensured by HAL_SRAM_GetState() function.

• Retrieve the clock frequency. This functionality is ensured by HAL_SRAM_GetClockFreq() function.

The read and write process must be managed within the application side (outside the HAL SRAM module) after fully configuring the FMC SRAM.