microscope-ring-light-remote-sw/dmx.c

#include "stm32f030x6.h"
#include <dmx.h>
#include <stdint.h>
#include <stm32f0xx.h>
#include <stdbool.h>
#include <stm-periph/stm32-gpio-macros.h>

static GPIO_TypeDef *dmx_tx_port;
static uint8_t dmx_tx_pin;
static uint32_t dmx_universe_length;
static uint8_t *dmx_data_ptr;
static uint16_t dmx_tx_break_len;
static uint16_t dmx_tx_break_pause;

static volatile enum dmx_tx_state tx_state;

/* USART1 TX is mapped on DMA Channel2 */

static void dmx_break(bool break_enable)
{
	uint32_t tmp;

	/* Force pin to low */
	dmx_tx_port->BSRR |= (1 << (dmx_tx_pin + 16));
	
	/* Change pin mode from alternate function (UART) to output and vice versa */
	tmp = dmx_tx_port->MODER;
	if (break_enable) {
		tmp &= MODER_DELETE(dmx_tx_pin);
		tmp |= OUTPUT(dmx_tx_pin);
	} else {
		tmp &= MODER_DELETE(dmx_tx_pin);
		tmp |= ALTFUNC(dmx_tx_pin);
	}
	dmx_tx_port->MODER = tmp;
}


void dmx_init(uint8_t *data, uint32_t universe_length, GPIO_TypeDef *tx_port, uint8_t tx_pin,
		uint16_t dmx_delay, uint16_t dmx_break_len, uint16_t break_pause)
{
	dmx_tx_pin = tx_pin;
	dmx_tx_port = tx_port;
	dmx_data_ptr = data;
	dmx_universe_length = universe_length;
	dmx_tx_break_len = dmx_break_len;
	dmx_tx_break_pause = break_pause;

	/* Enable UART1 and TIM14 clock */
	RCC->APB2ENR |= RCC_APB2ENR_USART1EN;
	RCC->APB1ENR |= RCC_APB1ENR_TIM14EN;

	/* Enable DMA clock */
	RCC->AHBENR |= RCC_AHBENR_DMAEN;

	/* Set baudrate: 48MHz / 250k = 129 */
	USART1->BRR = 192u;

	/* Two stop bits */
	USART1->CR2 = USART_CR2_STOP_1;

	/* Transmitter enable, USART enable, trawsnmission complete interrupt */
	USART1->CR1 = USART_CR1_TE | USART_CR1_UE | USART_CR1_TCIE;

	
	/* Configure TIM14 to count in 10 us steps */
	TIM14->PSC = 480u - 1u;

	/* Configure the reload value. Must be higher or equal to 200 */
	if (dmx_delay < 2000)
		dmx_delay = 2000;
	TIM14->ARR = dmx_delay - 1;

	/* Enable TIM14 interrupt on update */
	TIM14->DIER = TIM_DIER_UIE | TIM_DIER_CC1IE;
	NVIC_EnableIRQ(TIM14_IRQn);

	/* Enable Interrupts for USART and DMA */
	NVIC_EnableIRQ(USART1_IRQn);
	NVIC_EnableIRQ(DMA1_Channel2_3_IRQn);

	
}

void dmx_stream_start(void)
{
	tx_state = DMX_TX_IDLE;
	TIM14->CR1 |= TIM_CR1_CEN;
}

void dmx_stream_stop(void)
{
	tx_state = DMX_TX_OFF;
	TIM14->CR1 &= ~TIM_CR1_CEN;
	DMA1_Channel2->CCR = 0ul;
	__DSB();
	USART1->CR3 = 0ul;
}


void TIM14_IRQHandler(void)
{
	uint32_t sr;

	sr = TIM14->SR;

	/* Clear interrupt sources */
	TIM14->SR = 0;

	/* Start the break sequence if idle */
	switch (tx_state) {
	case DMX_TX_IDLE:
		if (!(sr & TIM_SR_UIF))
			break;
		tx_state = DMX_TX_BREAK;
		/* Disable the DMA transfer */
		USART1->CR3 = 0ul;

		TIM14->CCR1 = dmx_tx_break_len;

		/* Send break */
		dmx_break(true);
		break;

	case DMX_TX_BREAK:
		/* Stop break pulse */
		dmx_break(false);
		TIM14->CCR1 = dmx_tx_break_len + dmx_tx_break_pause;
		tx_state = DMX_TX_BREAK_PAUSE;
		break;
	case DMX_TX_BREAK_PAUSE:
		/* Send null byte */
		tx_state = DMX_TX_NULLBYTE;
		USART1->TDR = 0x00;
		break;
	default:
		break;
	}
}

enum dmx_tx_state dmx_tx_get_current_state(void)
{
	return tx_state;
}

void USART1_IRQHandler(void)
{
	uint32_t isr;

	isr = USART1->ISR;

	/* Clear interrupt flag */
	USART1->ICR = USART_ICR_TCCF;

	if (isr & USART_ISR_TC) {
		if (tx_state == DMX_TX_NULLBYTE) {
			/* Null byte transferred. Go to data state and setup DMA */
			tx_state = DMX_TX_DATA;
			USART1->CR3 |= USART_CR3_DMAT;
			
			DMA1_Channel2->CPAR = (uint32_t)&USART1->TDR;
			DMA1_Channel2->CMAR = (uint32_t)dmx_data_ptr;
			DMA1_Channel2->CNDTR = dmx_universe_length & 0xFFFF;
			DMA1_Channel2->CCR = DMA_CCR_PL_1 | DMA_CCR_MINC | DMA_CCR_DIR | DMA_CCR_TCIE | DMA_CCR_EN;
		}
	}
}

void DMA_CH2_3_DMA2_CH1_2_IRQHandler(void)
{
	uint32_t isr;

	isr = DMA1->ISR;
	DMA1->IFCR = isr & DMA_ISR_TCIF2;

	if (isr & DMA_ISR_TCIF2) {
		/* Channnel 2 trasnfer complete. Universe trasnferred */
		tx_state = DMX_TX_IDLE;
		DMA1_Channel2->CCR = 0u;
		USART1->CR3 &= ~USART_CR3_DMAT;
	}
}