2.86 QUAD MODE SPI HOST CONTROLLER (QMSPI)
The Quad Mode SPI Host Controller (QMSPI) may be used to communicate with various peripheral devices that use a Serial Peripheral Interface, such as EEPROMS, DACs and ADCs. The controller can be configured to support advanced SPI Flash devices with multiphase access protocols. Data can be transferred in Half Duplex, Single Data Rate, Dual Data Rate and Quad Data Rate modes. In all modes and all SPI clock speeds, the controller supports back-to-back reads and writes without clock stretching if internal bandwidth permits.
Using The Library
The QMSPI Peripheral Library is used to interface with the QMSPI based Serial Flash Memories operating in Single-bit SPI, Dual SPI and Quad SPI. The QMSPI Peripheral library provides blocking API's, which can be used to perform the following functionalists on the QMSPI Slave device.
Command and Register read/write
- Send a command to the slave device
- Read data from a register
- Write data to a register
Memory read/write
QMSPI_DESCRIPTOR_XFER_T data type needs to be filled for the following operations:
- Read data from the FLASH memory
- Write data to the FLASH memory
Here is an example code to read data from W25 FLASH memory using QMSPI peripheral
QMSPI_DESCRIPTOR_XFER_T qmspiDescXfer;
memset(&qmspiDescXfer, 0x00, sizeof(QMSPI_DESCRIPTOR_XFER_T));
qmspiDescXfer.address = address;
qmspiDescXfer.qmspi_ifc_mode = QUAD_OUTPUT;
qmspiDescXfer.ldma_enable = true;
qmspiDescXfer.ldma_channel_num = QMSPI_LDMA_CHANNEL_0;
qmspiDescXfer.command = APP_CMD_MEMORY_FAST_READ_QUAD;
qmspiDescXfer.num_of_dummy_byte = 4;
QMSPI0_DMATransferRead(&qmspiDescXfer, pReadBuffer, nBytes);
Library Interface
QMSPI peripheral library provides the following interfaces:
Functions
| Name | Description |
|---|---|
| QMSPIx_Initialize | Initializes given instance of the QMSPI peripheral |
| QMSPIx_ChipSelectSetup | Enables the specified hardware chip select |
| QMSPIx_TransferSetup | Configure QMSPI operational parameters at run time |
| QMSPIx_TapControlSet | Set control tap adjustment to QMSPI peripheral |
| QMSPIx_Write | Writes command/register to QMSPI slave device |
| QMSPIx_Read | Reads register from the QMSPI slave device |
| QMSPIx_IsTransmitterBusy | Returns transfer status of QMSPI peripheral |
| QMSPIx_DMATransferWrite | Writes data to the QMSPI slave device |
| QMSPIx_DMATransferRead | Reads data from the QMSPI slave device |
| QMSPIx_CallbackRegister | Allows application to register callback with PLIB |
| Name | Type | Description |
|---|---|---|
| QMSPI_CHIP_SELECT | Enum | Defines the data type to specify chip select number |
| QMSPI_INTERFACE_MODE | Enum | Defines the data type to specify interface mode |
| QMSPI_LDMA_CHANNEL_NUM | Typedef | Defines the data type to specify LDMA channel number |
| QMSPI_CLOCK_PHASE_MOSI | Enum | Identifies QMSPI Clock Phase MOSI Options |
| QMSPI_CLOCK_PHASE_MISO | Enum | Identifies QMSPI Clock Phase MISO Options |
| QMSPI_CLOCK_POLARITY | Enum | Identifies QMSPI Clock Polarity Options |
| QMSPI_TRANSFER_SETUP | Struct | Identifies the setup parameters which can be changed dynamically |
| QMSPI_XFER_T | Struct | Defines the data type for the QMSPI command/register transfer |
| QMSPI_DESCRIPTOR_XFER_T | Struct | Defines the data type for the QMSPI memory transfer |
| QMSPI_CALLBACK | Typedef | Pointer to a Callback function |