SPI with ASF

That's my first SPI master implementation.
I didn't find out yet how to initialize the PINs correctly with IOPORT, that's why I still use GPIO.

Here you are:

Add the following services/drivers to your project with ASF Wizard:

• GPIO
• IOPORT
• SPI
• Interrupt management
• System Clock Control

In your init.c file initialise the drivers and services.

#include <asf.h>
#include <board.h>
#include <conf_board.h>

void board_init(void)
{

 WDT->WDT_MR = WDT_MR_WDDIS; //switch off watchdog
 
 sysclk_init();
 ioport_init();
 irq_initialize_vectors();
 cpu_irq_enable();
 
 //Set Led Pin directions
 ioport_set_pin_dir(LED0_PIN,IOPORT_DIR_OUTPUT);
 ioport_set_pin_dir(LED1_PIN,IOPORT_DIR_OUTPUT);
}

SPI init
This init method will set up SPI in master mode, SPI mode will be SPI mode 0, clock rate around 1MHz.

#define SPI_ID            ID_SPI
#define SPI_MASTER_BASE     SPI
#define SPI_MISO_GPIO  (PIO_PA12_IDX)
#define SPI_MISO_FLAGS (PIO_PERIPH_A | PIO_DEFAULT)
#define SPI_MOSI_GPIO  (PIO_PA13_IDX)
#define SPI_MOSI_FLAGS (PIO_PERIPH_A | PIO_DEFAULT)
#define SPI_SPCK_GPIO  (PIO_PA14_IDX)
#define SPI_SPCK_FLAGS (PIO_PERIPH_A | PIO_DEFAULT)
#define SPI_NPCS0_GPIO            (PIO_PA11_IDX)
#define SPI_NPCS1_GPIO            (PIO_PA31_IDX)
#define SPI_NPCS1_FLAGS           (PIO_PERIPH_A | PIO_DEFAULT)
#define SPI_CHIP_SEL 1    //Use SPI Chip Select 1 (SPI_NPCS1_GPIO) for CS
#define SPI_CHIP_PCS spi_get_pcs(SPI_CHIP_SEL)

/* Clock polarity. */
#define SPI_CLK_POLARITY 0

/* Clock phase. */
#define SPI_CLK_PHASE 0

/* Delay before SPCK. */
//#define SPI_DLYBS 0x40
#define SPI_DLYBS 0xFF

/* Delay between consecutive transfers. */
#define SPI_DLYBCT 0x10
/* SPI clock setting (Hz). */
static uint32_t gs_ul_spi_clock = 1000000;

//Paramteres:
//  data: data to be sent
//  last_byte: either 0 or 1. 
//   0-There are following bytes to be sent. The following bytes and the current byte composes one data-unit, CS should be kept low after sending out the current byte
//   1-Last byte of a data unit. CS will be set to HIGH when the current byte has been sent out.
void spi_tx(uint8_t data,uint8_t last_byte)
{
 spi_write(SPI,data,SPI_CHIP_SEL,last_byte);
 while ((spi_read_status(SPI) & SPI_SR_RDRF) == 0);/* Wait transfer done. */
}

uint8_t spi_rx(void)
{
 uint8_t tmp;
 spi_read (SPI,&tmp,SPI_CHIP_SEL);
 return tmp;
}

void spi_init(void)
{
        //Assign I/O lines to peripheral
 gpio_configure_pin(SPI_MISO_GPIO, SPI_MISO_FLAGS);
 gpio_configure_pin(SPI_MOSI_GPIO, SPI_MOSI_FLAGS);
 gpio_configure_pin(SPI_SPCK_GPIO, SPI_SPCK_FLAGS);
 gpio_configure_pin(SPI_NPCS1_GPIO, SPI_NPCS1_FLAGS);
 
 spi_enable_clock(SPI_MASTER_BASE);
 spi_disable(SPI_MASTER_BASE);
 spi_reset(SPI_MASTER_BASE);
 spi_set_lastxfer(SPI_MASTER_BASE);
 spi_set_master_mode(SPI_MASTER_BASE);
 spi_disable_mode_fault_detect(SPI_MASTER_BASE);
 spi_set_peripheral_chip_select_value(SPI_MASTER_BASE, SPI_CHIP_PCS);
 spi_configure_cs_behavior(SPI, 1, SPI_CS_RISE_NO_TX);
 spi_set_clock_polarity(SPI_MASTER_BASE, SPI_CHIP_SEL, SPI_CLK_POLARITY);
 spi_set_clock_phase(SPI_MASTER_BASE, SPI_CHIP_SEL, SPI_CLK_PHASE);
 spi_set_bits_per_transfer(SPI_MASTER_BASE, SPI_CHIP_SEL,
 SPI_CSR_BITS_8_BIT);
 spi_set_baudrate_div(SPI_MASTER_BASE, SPI_CHIP_SEL,(sysclk_get_cpu_hz() / gs_ul_spi_clock));
 spi_set_transfer_delay(SPI_MASTER_BASE, SPI_CHIP_SEL, SPI_DLYBS,SPI_DLYBCT);
 spi_enable(SPI_MASTER_BASE);
}

Call spi_init either in init.c or in your main block. After that, you can start to send/receive data through SPI with spi_tx/spi_rx functions.

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If you like my post and/or it was useful, please, leave some comment. If you don't, let me know that too. :-)

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