microscope-ring-light/firmware/dmx.c

#include <ring-light/dmx.h>
#include <stm32f0xx.h>

static uint32_t dmx_base_channel;

enum dmx_rx_state_enum {
	DMX_RX_WAIT_FOR_BREAK = 0,
	DMX_RX_DATA,
};

/**
 * @brief DMX data received. Contains the whole DMX universe including the first 0 byte.
 * The controller does check the first byte to be zero.
 */
static volatile uint8_t dmx_channel_data[DMX_UNIVERSE_SIZE + 1];

static volatile enum dmx_rx_state_enum dmx_rx_state;
static volatile uint32_t dmx_write_pointer;

void dmx_init(uint32_t base_channel)
{
	int i;
	volatile uint8_t *ptr;

	for (i = 0, ptr = dmx_channel_data; i < DMX_USED_CHANNEL_COUNT; i++, ptr++) {
		*ptr = 0u;
	}

	dmx_base_channel = base_channel;
	dmx_write_pointer = 0u;
	dmx_rx_state = DMX_RX_WAIT_FOR_BREAK;

	/* Enable GPIOA and USART1 clock */
	RCC->AHBENR |= RCC_AHBENR_GPIOAEN;
	RCC->APB2ENR |= RCC_APB2ENR_USART1EN;

	/* Switch RXTX pin low, activating permanent READ mode */
	GPIOA->MODER |= (0x1<<(2*5));
	GPIOA->BRR |= (1<<5);

	/* Switch PA10 to RX alternate function of USART1 (AF1) */
	GPIOA->MODER |= (0x2<<(2*10));
	GPIOA->AFR[1] |=(0x1<<(4*2));

	/* Set baudrate: 48MHz / 250k = 129 */
	USART1->BRR = 192u;
	USART1->CR3 = USART_CR3_EIE;
	USART1->CR2 = USART_CR2_STOP_1;
	USART1->CR1 = USART_CR1_RXNEIE | USART_CR1_RE | USART_CR1_UE;

	/* Map USART1 RX to DMA Channel 3 */
	SYSCFG->CFGR1 &= ~SYSCFG_CFGR1_USART1RX_DMA_RMP;

	NVIC_EnableIRQ(USART1_IRQn);
}


const uint8_t *dmx_get_data()
{
	return (const uint8_t *)&dmx_channel_data[1];
}

void USART1_IRQHandler(void)
{
	uint32_t isr;
	uint8_t dreg;

	isr = USART1->ISR;
	USART1->ICR = USART_ICR_ORECF | USART_ICR_NCF | USART_ICR_FECF;

	if (isr & USART_ISR_FE) {
		/* Frame error received. Start of DMX frame */
		dmx_write_pointer = 0u;
		dmx_rx_state = DMX_RX_DATA;
		/* Flush RX data */
		USART1->RQR = USART_RQR_RXFRQ;
	} else if (isr & USART_ISR_RXNE) {
		/* Received valid symbol */
		dreg = (uint8_t)USART1->RDR;

		if (dmx_rx_state == DMX_RX_DATA) {
			/* Ready to recieve data */
			if (dmx_write_pointer < (DMX_UNIVERSE_SIZE + 1)) {
				dmx_channel_data[dmx_write_pointer] = dreg;
				dmx_write_pointer++;
			} else {
				dmx_rx_state = DMX_RX_WAIT_FOR_BREAK;
			}
		}

	}

	__DSB();
}

void DMA_CH2_3_DMA2_CH1_2_IRQHandler()
{

}