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.

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.

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)

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#

PSRAM Chip Select and Base Address

PSRAM Pin Configuration

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 136 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 157 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 167 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 303 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 314 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 324 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 343 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 365 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 389 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 414 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 431 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 443 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 456 of file components/device/silabs/si91x/mcu/drivers/unified_api/inc/sl_si91x_psram.h