TI-RTOS Drivers
tidrivers_full_2_20_00_08
|
SPI driver implementation for a EUSCI peripheral on MSP432 using the micro DMA controller.
============================================================================
The SPI header file should be included in an application as follows:
Refer to SPI.h for a complete description of APIs & example of use.
This SPI driver implementation is designed to operate on a EUCSI controller in SPI mode.
The SPIMSP432DMA operates the controller in 3-pin mode; therefore it is not safe to use in a multi-master SPI bus environment. It is the application's responsibility to assert and de-assert a GPIO pin for chip select purposes.
Chip select type | SPI_MASTER mode | SPI_SLAVE mode |
---|---|---|
Hardware chip select | Not available on this peripheral. | |
Software chip select | The application is responsible to ensure that correct SPI slave is selected before performing a SPI_transfer(). | Up to the application's implementation. |
The MSP432 DMA controller has 4 interrupt vectors to handle all DMA related IRQ. Due to the "shared" nature of the DMA interrupts, this driver implementation requires each SPI instance to explicitly use a single DMA interrupt. It is up to the application to ensure no two peripherals are configured to respond to a given DMA interrupt at any moment.
A uint32_t scratch buffer is used to allow SPI_transfers where txBuf or rxBuf are NULL. Rather than requiring txBuf or rxBuf to have a dummy buffer of size of the transfer count, a single DMA accessible uint32_t scratch buffer is used. When txBuf is NULL, an internal scratch buffer is initialized to the defaultTxBufValue so the DMA will send some known value. Each SPI driver instance should uses its own scratch buffer.
The EUSCI controller only supports 8-bit data frames.
dataSize | buffer element size |
---|---|
8 bits | uint8_t |
The DMA contoller only supports data transfers of upto 1024 data frames. Each SPI driver instance requires 2 DMA channels (Tx and Rx) to operate.
Ensure that the txBuf and rxBuf (in SPI_Transaction) point to memory that is accessible by the DMA.
#include <stdint.h>
#include <ti/drivers/ports/HwiP.h>
#include <ti/drivers/ports/SemaphoreP.h>
#include <ti/drivers/Power.h>
#include <ti/drivers/SPI.h>
#include <ti/drivers/dma/UDMAMSP432.h>
Go to the source code of this file.
Data Structures | |
struct | SPIMSP432DMA_HWAttrs |
SPIMSP432DMA Hardware attributes These fields, with the exception of intPriority, are used by driverlib APIs and therefore must be populated by driverlib macro definitions. For MSP430Ware these definitions are found in: More... | |
struct | SPIMSP432DMA_Object |
SPIMSP432DMA Object. More... | |
Typedefs | |
typedef struct SPIMSP432DMA_HWAttrs | SPIMSP432DMA_HWAttrs |
SPIMSP432DMA Hardware attributes These fields, with the exception of intPriority, are used by driverlib APIs and therefore must be populated by driverlib macro definitions. For MSP430Ware these definitions are found in: More... | |
typedef struct SPIMSP432DMA_Object | SPIMSP432DMA_Object |
SPIMSP432DMA Object. More... | |
typedef struct SPIMSP432DMA_Object * | SPIMSP432DMA_Handle |
Variables | |
const SPI_FxnTable | SPIMSP432DMA_fxnTable |
typedef struct SPIMSP432DMA_HWAttrs SPIMSP432DMA_HWAttrs |
SPIMSP432DMA Hardware attributes These fields, with the exception of intPriority, are used by driverlib APIs and therefore must be populated by driverlib macro definitions. For MSP430Ware these definitions are found in:
intPriority is the SPI peripheral's interrupt priority, as defined by the underlying OS. It is passed unmodified to the underlying OS's interrupt handler creation code, so you need to refer to the OS documentation for usage. For example, for SYS/BIOS applications, refer to the ti.sysbios.family.arm.m3.Hwi documentation for SYS/BIOS usage of interrupt priorities. If the driver uses the ti.drivers.ports interface instead of making OS calls directly, then the HwiP port handles the interrupt priority in an OS specific way. In the case of the SYS/BIOS port, intPriority is passed unmodified to Hwi_create().
A sample structure is shown below:
typedef struct SPIMSP432DMA_Object SPIMSP432DMA_Object |
SPIMSP432DMA Object.
The application must not access any member variables of this structure!
typedef struct SPIMSP432DMA_Object * SPIMSP432DMA_Handle |
const SPI_FxnTable SPIMSP432DMA_fxnTable |