PSRAM Driver#


Introduction#

PSRAM (Pseudo Static Random Access Memory) is a random-access memory whose internal structure is based on dynamic memory with refresh control signals generated internally, in the standby mode, so that it can mimic the functionality of a static memory. It combines the high density of DRAM with the ease-of-use of true SRAM. The M4 core communicates with the PSRAM via Quad SPI interface.

Memory Architecture DiagramMemory Architecture Diagram

To enhance performance, PSRAM access is optimized through a cache memory system. This "Modified Harvard Architecture" allows the core to access instructions and data through separate caches (Data cache and Instruction cache), which then access the common PSRAM. When data is already in the cache ("Cache Hit"), it’s quickly provided to the core. If not ("Cache Miss"), the cache retrieves the data from PSRAM, improving overall performance.

The architecture is designed to ensure efficient memory access, with the data path supported by a 16KB, 4-way set associative cache with a 32-byte cache line. The instruction path leverages the existing instruction cache shared between flash and PSRAM.

PSRAM AccessibilityPSRAM Accessibility


Configuration#

PSRAM Device Configuration#

The PSRAM Driver offers configuring the following:

  • Read-Write type

    • Normal: This is supported only in SPI interface mode. Supports a maximum frequency of 33MHz. Uses normal read and normal write commands.

    • Fast: Supported in SPI and QPI mode. Uses fast read and normal write.

    • Quad IO: Supported in SPI and QPI mode. Uses fast quad read and write.

  • Interface mode

    • SPI Mode (Serial IO)

    • QPI Mode (Quad IO)

  • Operation frequency source

    • Interface PLL Clock

    • ULP Reference Clock

    • SoC PLL Clock

    • M4_SOCCLKNOSWLSYNCCLKTREEGATED Clock

Linker configurations#

The text segment, data segment, bss, heap, and stack can be placed in PSRAM by installing the respective components present under "PSRAM Linker Configurations" from the "SOFTWARE COMPONENTS" GUI. Since PSRAM is already initialized in the bootloader, these components can be installed and the respective segments can be placed in PSRAM without installing the "PSRAM Core" component and without initializing PSRAM from the application.

  • For more information on configuring available parameters, see the respective peripheral example readme document.


Usage#

The PSRAM Driver and QSPI are initialized by the bootloader with Quad IO read-write type and QPI interface. The application is not required to reinitialize the PSRAM device and QSPI unless the configurations required are different from the default set by the bootloader.

The PSRAM device handle "PSRAM_Device" of type sl_psram_info_type_t is defined in "sl_si91x_psram_handle.c".

sl_si91x_psram_uninit assumes that PSRAM was initialized with QPI mode and exits QPI mode within the definition. If the PSRAM configuration in the boot code has SPI mode enabled, the user is expected to comment out the exit QPI mode function call in sl_si91x_psram_uninit.

To reconfigure and initialize PSRAM, set the required configurations from the PSRAM Core component and call sl_si91x_psram_init within the application.

Modules#

sl_psram_id_type_t

sl_psram_info_type_t

PSRAM Commands

PSRAM Timings

Enumerations#

enum
sl_psram_return_type_t {
PSRAM_SUCCESS
PSRAM_FAILURE
PSRAM_UNKNOWN
PSRAM_UNKNOWN_DEVICE
PSRAM_CLOCK_INIT_FAILURE
PSRAM_NOT_INITIALIZED
PSRAM_SUPPORTED_DEVICE
PSRAM_DEVICE_MISMATCH
PSRAM_INVALID_HSIZE
PSRAM_NULL_ADDRESS
PSRAM_INVALID_ADDRESS_LENGTH
PSRAM_AUTO_MODE
PSRAM_MANUAL_MODE
PSRAM_UNSUPPORTED_SECURITY
PSRAM_MAX_SEC_SEGMENT_REACH
}

PSRAM return error code.

enum
sl_psram_burst_size_type_t {
_WRAP16
_WRAP32
_WRAP64
_WRAP512
}

Wrap burst size enum.

enum
sl_psram_dma_status_type_t {
DMA_NONE
DMA_DONE
DMA_FAIL
}

PSRAM DMA status enum.

Functions#

sl_psram_return_type_t
sl_si91x_psram_init(void)

To configure and initialize the PSRAM Device.

sl_psram_return_type_t
sl_si91x_psram_uninit(void)

To uninitialize the PSRAM Device.

sl_psram_return_type_t
sl_si91x_psram_reset(void)

To reset the PSRAM Device.

sl_psram_return_type_t
sl_si91x_psram_manual_write_in_blocking_mode(uint32_t addr, void *SourceBuf, uint8_t hSize, uint32_t length)

To write data to PSRAM in manual mode.

sl_psram_return_type_t
sl_si91x_psram_manual_read_in_blocking_mode(uint32_t addr, void *DestBuf, uint8_t hSize, uint32_t length)

To read data from PSRAM in manual mode.

sl_psram_return_type_t
sl_si91x_psram_manual_write_in_dma_mode(uint32_t addr, void *SourceBuf, uint8_t hSize, uint32_t length, sl_psram_dma_status_type_t *dmaStatus)

To write data to PSRAM in manual mode using DMA.

sl_psram_return_type_t
sl_si91x_psram_manual_read_in_dma_mode(uint32_t addr, void *DestBuf, uint8_t hSize, uint32_t length, sl_psram_dma_status_type_t *dmaStatus)

To read data from PSRAM in manual mode using DMA.

sl_psram_return_type_t
sl_si91x_psram_sleep(void)

To put the PSRAM device in sleep mode.

sl_psram_return_type_t
sl_si91x_psram_wakeup(void)

To exit the PSRAM device from sleep mode.

sl_psram_return_type_t
sl_si91x_psram_enable_encry_decry(uint16_t keySize)

To enable CTR encryption-decryption on PSRAM.

Enumeration Documentation#

sl_psram_return_type_t#

sl_psram_return_type_t

PSRAM return error code.

Enumerator
PSRAM_SUCCESS

No error.

PSRAM_FAILURE

Generic error.

PSRAM_UNKNOWN

Unknown request.

PSRAM_UNKNOWN_DEVICE

Unknown PSRAM Device.

PSRAM_CLOCK_INIT_FAILURE

Clock init failure.

PSRAM_NOT_INITIALIZED

PSRAM not initialized.

PSRAM_SUPPORTED_DEVICE

PSRAM Device supported.

PSRAM_DEVICE_MISMATCH

PSRAM Device mismatch.

PSRAM_INVALID_HSIZE

Invalid size of element.

PSRAM_NULL_ADDRESS

Null address.

PSRAM_INVALID_ADDRESS_LENGTH

Invalid address length.

PSRAM_AUTO_MODE

PSRAM Auto mode.

PSRAM_MANUAL_MODE

PSRAM Manual mode.

PSRAM_UNSUPPORTED_SECURITY

Unsupported security.

PSRAM_MAX_SEC_SEGMENT_REACH

Maximum secure segment reached.


Definition at line 123 of file components/device/silabs/si91x/mcu/drivers/unified_api/inc/sl_si91x_psram.h

sl_psram_burst_size_type_t#

sl_psram_burst_size_type_t

Wrap burst size enum.

Enumerator
_WRAP16

Burst wrap size 16 Bytes.

_WRAP32

Burst wrap size 32 Bytes.

_WRAP64

Burst wrap size 64 Bytes.

_WRAP512

Burst wrap size 512 Bytes.


Definition at line 144 of file components/device/silabs/si91x/mcu/drivers/unified_api/inc/sl_si91x_psram.h

sl_psram_dma_status_type_t#

sl_psram_dma_status_type_t

PSRAM DMA status enum.

Enumerator
DMA_NONE

DMA status default.

DMA_DONE

DMA transfer completed.

DMA_FAIL

DMA transfer failed.


Definition at line 154 of file components/device/silabs/si91x/mcu/drivers/unified_api/inc/sl_si91x_psram.h

Function Documentation#

sl_si91x_psram_init#

sl_psram_return_type_t sl_si91x_psram_init (void )

To configure and initialize the PSRAM Device.

Parameters
N/A

Returns


  • Status code indicating the result.

    • PSRAM_SUCCESS: Initialization successful

    • PSRAM_FAILURE: Initialization failed

Note

  • The configurations for initialization are taken from the PSRAM Device config header file. The selection of the configuration file happens implicitly based on the radio board selection.


Definition at line 290 of file components/device/silabs/si91x/mcu/drivers/unified_api/inc/sl_si91x_psram.h

sl_si91x_psram_uninit#

sl_psram_return_type_t sl_si91x_psram_uninit (void )

To uninitialize the PSRAM Device.

Parameters
N/A

Returns


  • Status code indicating the result.

    • PSRAM_SUCCESS: Uninitialization successful

    • PSRAM_FAILURE: Uninitialization failed


Definition at line 301 of file components/device/silabs/si91x/mcu/drivers/unified_api/inc/sl_si91x_psram.h

sl_si91x_psram_reset#

sl_psram_return_type_t sl_si91x_psram_reset (void )

To reset the PSRAM Device.

Parameters
N/A

Returns

  • Status code indicating the result.

    • PSRAM_SUCCESS: Reset successful

    • PSRAM_FAILURE: Reset failed


Definition at line 311 of file components/device/silabs/si91x/mcu/drivers/unified_api/inc/sl_si91x_psram.h

sl_si91x_psram_manual_write_in_blocking_mode#

sl_psram_return_type_t sl_si91x_psram_manual_write_in_blocking_mode (uint32_t addr, void * SourceBuf, uint8_t hSize, uint32_t length)

To write data to PSRAM in manual mode.

Parameters
[in]addr

PSRAM address for the write operation

[in]SourceBuf

Reference to the source buffer

[in]hSize

Size of each element

[in]length

Number of elements for the write operation

Returns

  • Status code indicating the result.

    • PSRAM_SUCCESS: Write operation successful

    • PSRAM_FAILURE: Write operation failed


Definition at line 330 of file components/device/silabs/si91x/mcu/drivers/unified_api/inc/sl_si91x_psram.h

sl_si91x_psram_manual_read_in_blocking_mode#

sl_psram_return_type_t sl_si91x_psram_manual_read_in_blocking_mode (uint32_t addr, void * DestBuf, uint8_t hSize, uint32_t length)

To read data from PSRAM in manual mode.

Parameters
[in]addr

PSRAM address for the read operation

[in]DestBuf

Size of each element

[in]hSize

Number of elements for the read operation

[out]length

Reference to the destination buffer

Returns

  • Status code indicating the result.

    • PSRAM_SUCCESS: Read operation successful

    • PSRAM_FAILURE: Read operation failed


Definition at line 352 of file components/device/silabs/si91x/mcu/drivers/unified_api/inc/sl_si91x_psram.h

sl_si91x_psram_manual_write_in_dma_mode#

sl_psram_return_type_t sl_si91x_psram_manual_write_in_dma_mode (uint32_t addr, void * SourceBuf, uint8_t hSize, uint32_t length, sl_psram_dma_status_type_t * dmaStatus)

To write data to PSRAM in manual mode using DMA.

Parameters
[in]addr

PSRAM address for the write operation

[in]SourceBuf

Reference to the source buffer

[in]hSize

Size of each element

[in]length

Number of elements for the write operation

[out]dmaStatus

DMA operation completion status

Returns

  • Status code indicating the result.

    • PSRAM_SUCCESS: Write operation successful

    • PSRAM_FAILURE: Write operation failed


Definition at line 376 of file components/device/silabs/si91x/mcu/drivers/unified_api/inc/sl_si91x_psram.h

sl_si91x_psram_manual_read_in_dma_mode#

sl_psram_return_type_t sl_si91x_psram_manual_read_in_dma_mode (uint32_t addr, void * DestBuf, uint8_t hSize, uint32_t length, sl_psram_dma_status_type_t * dmaStatus)

To read data from PSRAM in manual mode using DMA.

Parameters
[in]addr

PSRAM address for the read operation

[out]DestBuf

Reference to the destination buffer

[in]hSize

Size of each element

[in]length

Number of elements for the read operation

[out]dmaStatus

DMA operation completion status

Returns

  • Status code indicating the result.

    • PSRAM_SUCCESS: Read operation successful

    • PSRAM_FAILURE: Read operation failed


Definition at line 401 of file components/device/silabs/si91x/mcu/drivers/unified_api/inc/sl_si91x_psram.h

sl_si91x_psram_sleep#

sl_psram_return_type_t sl_si91x_psram_sleep (void )

To put the PSRAM device in sleep mode.

Parameters
N/A

Sleep mode is a feature that puts the PSRAM device in an ultra-low power state, while retaining the stored data.

Returns

  • Status code indicating the result.

    • PSRAM_SUCCESS: Sleep mode enabled successfully

    • PSRAM_FAILURE: Failed to enable sleep mode


Definition at line 418 of file components/device/silabs/si91x/mcu/drivers/unified_api/inc/sl_si91x_psram.h

sl_si91x_psram_wakeup#

sl_psram_return_type_t sl_si91x_psram_wakeup (void )

To exit the PSRAM device from sleep mode.

Parameters
N/A

Returns

  • Status code indicating the result.

    • PSRAM_SUCCESS: Wakeup successful

    • PSRAM_FAILURE: Wakeup failed

Note

  • This function call re-initializes the PSRAM device after the wakeup sequence.


Definition at line 430 of file components/device/silabs/si91x/mcu/drivers/unified_api/inc/sl_si91x_psram.h

sl_si91x_psram_enable_encry_decry#

sl_psram_return_type_t sl_si91x_psram_enable_encry_decry (uint16_t keySize)

To enable CTR encryption-decryption on PSRAM.

Parameters
[in]keySize

Pass 128/256-bit size

Returns

  • Status code indicating the result.

    • PSRAM_SUCCESS: Encryption-decryption enabled successfully

    • PSRAM_FAILURE: Failed to enable encryption-decryption


Definition at line 443 of file components/device/silabs/si91x/mcu/drivers/unified_api/inc/sl_si91x_psram.h