/********************/
/** MAKROS 	   **/
/********************/

#define OMD_CHIP_SELECT_ENABLE() 	NRF_GPIO->OUTCLR = (1UL<<OMD_SPI_CSN_PIN)	// OMD \CS = 0
#define OMD_CHIP_SELECT_DISABLE() 	NRF_GPIO->OUTSET = (1UL<<OMD_SPI_CSN_PIN)	// OMD \CS = 1
#define OMD_CLOCK_SET_IDLE()		NRF_GPIO->OUTCLR = (1UL<<OMD_SPI_CLK_PIN)	// OMD CLK = 0
#define OMD_MOSI_SET_IDLE()		NRF_GPIO->OUTCLR = (1UL<<OMD_SPI_MOSI_PIN)	// OMD MOSI = 0
#define OMD_SPIM_ENABLE()		OMD_SPI_INSTANCE->ENABLE = 0xFUL
#define OMD_SPIM_DISABLE()		OMD_SPI_INSTANCE->ENABLE = 0x0UL



/********************/
/** INIT FUNCTIONS **/
/********************/

static void omd_init_gpio(void)
{
	// config GPIO pins for standard drive strength with no sense capability (see nrf_gpio.h)
	nrf_gpio_cfg_output(OMD_SPI_CSN_PIN); 				// CSN  -> output
	nrf_gpio_cfg_output(OMD_SPI_MOSI_PIN); 				// MOSI -> output
	nrf_gpio_cfg_input(OMD_SPI_MISO_PIN, NRF_GPIO_PIN_NOPULL); 	// MISO -> input
	nrf_gpio_cfg(							// CLK  -> output
            OMD_SPI_CLK_PIN,
            NRF_GPIO_PIN_DIR_OUTPUT,
            NRF_GPIO_PIN_INPUT_CONNECT,					// input buffer needs to be connected for CLK output
            NRF_GPIO_PIN_NOPULL,
            NRF_GPIO_PIN_S0S1,
            NRF_GPIO_PIN_NOSENSE);

	// set idle values for output pins 
	OMD_CHIP_SELECT_DISABLE();
	OMD_CLOCK_SET_IDLE();
	OMD_MOSI_SET_IDLE();
}


static bool omd_init_spi(void)
{
	// disable modules with shared ressources (see nRF52832 OPS v0.6 / Table 8: Instantiation table)
	if(OMD_SPI_INSTANCE == NRF_SPIM0)
	{
		NRF_SPIS0->ENABLE = 0UL;
		NRF_TWIM0->ENABLE = 0UL;
		NRF_TWIS0->ENABLE = 0UL;
	}
	else if(OMD_SPI_INSTANCE == NRF_SPIM1)
	{
		NRF_SPIS1->ENABLE = 0UL;
		NRF_TWIM1->ENABLE = 0UL;
		NRF_TWIS1->ENABLE = 0UL;
	}
	else if(OMD_SPI_INSTANCE == NRF_SPIM2)
	{
		NRF_SPIS1->ENABLE = 0UL;
	}
	else
	{
		return false; // incorrect SPIM instance
	}
	
	// reset registers
	OMD_SPI_INSTANCE->INTENCLR		= 0UL;		// ensure that all SPIM interrupts are disabled
	OMD_SPI_INSTANCE->SHORTS		= 0UL;		// ensure that SPIM shortcuts are disabled
	OMD_SPI_INSTANCE->EVENTS_STOPPED	= 0;
	OMD_SPI_INSTANCE->TASKS_STOP		= 1;		// ensure that SPIM is stopped
	OMD_SPI_INSTANCE->ENABLE		= 0UL;		// ensure that SPIM is disabled
	OMD_SPI_INSTANCE->EVENTS_STARTED	= 0;		// clear all pending events
	OMD_SPI_INSTANCE->EVENTS_ENDTX		= 0;
	OMD_SPI_INSTANCE->EVENTS_ENDRX		= 0;
	OMD_SPI_INSTANCE->EVENTS_END		= 0;
	
	// init GPIO pins for SPI usage
	omd_init_gpio();
	OMD_SPI_INSTANCE->PSEL.SCK	= (uint32_t)OMD_SPI_CLK_PIN;	// = 31
	OMD_SPI_INSTANCE->PSEL.MOSI	= (uint32_t)OMD_SPI_MOSI_PIN;	// = 30
	OMD_SPI_INSTANCE->PSEL.MISO	= (uint32_t)OMD_SPI_MISO_PIN;	// = 29
	
	// config RX registers
	OMD_SPI_INSTANCE->RXD.MAXCNT	= (uint32_t)OMD_RX_BUFFER_SIZE;	// define max. RX bytes according RX buffer size
	OMD_SPI_INSTANCE->RXD.PTR	= (uint32_t)&OMD_RX_Buffer;	// set RX data pointer to the RX buffer
	//OMD_SPI_INSTANCE->RXD.LIST	= SPIM_RXD_LIST_LIST_Msk;	// Use array list
	
	// config TX registers
	OMD_SPI_INSTANCE->TXD.MAXCNT	= (uint32_t)OMD_TX_BUFFER_SIZE;	// define max. TX bytes according TX buffer size
	OMD_SPI_INSTANCE->TXD.PTR	= (uint32_t)&OMD_TX_Buffer;	// set TX data pointer to the TX buffer
	//OMD_SPI_INSTANCE->TXD.LIST	= SPIM_TXD_LIST_LIST_Msk;	// Use array list
	
	// set config registers
	OMD_SPI_INSTANCE->FREQUENCY	= SPI_FREQUENCY_FREQUENCY_M1;
	OMD_SPI_INSTANCE->ORC		= (uint32_t)OMD_RX_ORC_VALUE;
	OMD_SPI_INSTANCE->CONFIG	= (uint32_t)((SPI_CONFIG_CPOL_ActiveHigh << SPI_CONFIG_CPOL_Pos)|
						(SPI_CONFIG_CPHA_Leading 	 << SPI_CONFIG_CPHA_Pos)|
						(SPI_CONFIG_ORDER_MsbFirst  	<< SPI_CONFIG_ORDER_Pos));
	
	return true;
}



/********************/
/** ACCESS	   **/
/********************/

bool omd_trigger_read_data(void)
{
	if(OMD_SPI_INSTANCE->EVENTS_STARTED != 0)
	{
		return false;	// SPI already in use
	}
	
	// configure RX & TX Buffers (TX -> DUMMY, RX -> RX)
	OMD_SPI_INSTANCE->RXD.MAXCNT	= (uint32_t)OMD_RX_BUFFER_SIZE;
	OMD_SPI_INSTANCE->RXD.PTR	= (uint32_t)&OMD_RX_Buffer;
	OMD_SPI_INSTANCE->TXD.MAXCNT	= (uint32_t)OMD_DUMMY_BUFFER_SIZE;
	OMD_SPI_INSTANCE->TXD.PTR	= (uint32_t)&OMD_Dummy_Buffer;
	
	omd_enable_rx_interrupt(true);		// enable RX interrupt
	OMD_SPIM_ENABLE();			// enable SPIM interface
	OMD_CHIP_SELECT_ENABLE();		// select OMD sensor
	
	OMD_SPI_INSTANCE->EVENTS_STARTED = 0;			// clear STARTED event
	OMD_SPI_INSTANCE->TASKS_START = 1;			// trigger START task
	while (OMD_SPI_INSTANCE->EVENTS_STARTED == 0) {}	// wait for STARTED event <-- will never happen
	OMD_SPI_INSTANCE->EVENTS_STOPPED = 0;			// clear STOPPED event

	return true;
}