SPI

SPI Driver.

Functions for interacting with peripheral devices over a serial peripheral bus (SPI)

Sysprops

sysprop	description
gpio_mosi	the master out GPIO
gpio_miso	the master in GPIO
gpio_cs	the chip select (low active) GPIO
gpio_clk	the master clock GPIO
baudrate	the desired baudrate

Functions Overview

	Name
CW_DRIVER_FUNC	spi_transfer(int hDev, const uint8_t * data_out, uint8_t * data_in, size_t len) Performs a SPI transfer on the specified device.
CW_DRIVER_FUNC	spi_read(int hDev, uint8_t * data, uint32_t len) read data from the SPI
CW_DRIVER_FUNC	spi_write(int hDev, const uint8_t * data, uint32_t len) write data to the SPI

Function Details

function spi_transfer

CW_DRIVER_FUNC spi_transfer(
    int hDev,
    const uint8_t * data_out,
    uint8_t * data_in,
    size_t len
)

Performs a SPI transfer on the specified device.

Parameters:

• hDev The handle of the device.
• data_out Pointer to the data to be transmitted.
• data_in Pointer to the buffer for received data.
• len The number of bytes to transfer.

Return: CW_DRIVER_OK if the transfer was successful, otherwise an error code.

This function transfers data between the device and the SPI bus.

function spi_read

CW_DRIVER_FUNC spi_read(
    int hDev,
    uint8_t * data,
    uint32_t len
)

read data from the SPI

Parameters:

• hDev device handle as returned by open(const char*)
• data
• len

Return:

convenience function that simply transmits 0xff characters to the communications partner

function spi_write

CW_DRIVER_FUNC spi_write(
    int hDev,
    const uint8_t * data,
    uint32_t len
)

write data to the SPI

Parameters:

• hDev device handle as returned by open(const char*)
• data buffer holding the data to be written
• len length of the buffer

Return:

convenience function that simply discards received bytes during the transfer