Implement Uart RX functionality. UART RX works. DMX frame detection not yet implemented.

firmware/dmx.c

@@ -1 +1,65 @@
 #include <ring-light/dmx.h>
+#include <stm32f0xx.h>
+
+static volatile bool dmx_new_data_avail = false;
+static uint32_t dmx_base_channel;
+static uint8_t dmx_channel_data[DMX_USED_CHANNEL_COUNT];
+
+void dmx_init(uint32_t base_channel)
+{
+	int i;
+	uint8_t *ptr;
+
+	dmx_new_data_avail = false;
+	for (i = 0, ptr = dmx_channel_data; i < DMX_USED_CHANNEL_COUNT; i++, ptr++) {
+		*ptr = 0u;
+	}
+
+	dmx_base_channel = base_channel;
+
+	/* 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;
+
+	NVIC_EnableIRQ(USART1_IRQn);
+}
+
+bool dmx_new_data_available()
+{
+	return dmx_new_data_avail;
+}
+
+const uint8_t *dmx_get_data()
+{
+	return dmx_channel_data;
+}
+
+void USART1_IRQHandler(void)
+{
+	uint32_t isr;
+	volatile uint8_t dreg;
+
+	isr = USART1->ISR;
+	USART1->ICR = USART_ICR_ORECF | USART_ICR_NCF | USART_ICR_FECF;
+
+	if (isr & USART_ISR_RXNE) {
+		dreg = (uint8_t)USART1->RDR;
+		dmx_channel_data[0] = dreg;
+	}
+
+	__DSB();
+}

firmware/include/ring-light/dmx.h

@@ -1,4 +1,43 @@
 #ifndef _DMX_H_
 #define _DMX_H_
 
+
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#define DMX_UNIVERSE_SIZE (255u)
+#define DMX_USED_CHANNEL_COUNT (129u)
+
+/**
+ * @brief Init DMX reception
+ *
+ * DMX data is received from the base channel onwards:
+ * - R LED1
+ * - G LED1
+ * - B LED1
+ * - W LED1
+ * - R LED2
+ * ...
+ * - W LED32
+ * - W DISCRETE
+ *
+ * In Sum: 129 8 bit channels
+ *
+ * @param base_channel Base channel the ring light will listen on
+ */
+void dmx_init(uint32_t base_channel);
+
+/**
+ * @brief Has new DMX data been received?
+ * @return true if new data is available
+ */
+bool dmx_new_data_available(void);
+
+/**
+ * @brief Returns the array of the 129 DMX channels
+ * @return
+ */
+const uint8_t *dmx_get_data(void);
+
 #endif /* _DMX_H_ */

firmware/main.c

@@ -2,6 +2,7 @@
 #include <cmsis/core_cm0.h>
 #include <stdbool.h>
 #include <ring-light/temp-adc.h>
+#include <ring-light/dmx.h>
 
 #define RING_MAX_LED	32u
 #define MAX_TEMP_CELSIUS 70
@@ -37,7 +38,7 @@ int main(void)
 	uint8_t led_pwm_val = 0u;
 
 	bool button_pressed = false;
-	enum ring_modes mode = RING_MODE_ALL;
+	enum ring_modes mode;
 
 	RCC->AHBENR |= RCC_AHBENR_GPIOAEN | RCC_AHBENR_GPIOBEN;
 	RCC->APB1ENR |= RCC_APB1ENR_TIM3EN | RCC_APB1ENR_TIM14EN;
@@ -83,6 +84,7 @@ int main(void)
 	mode    = RING_MODE_WHITE_DISCRETE;
 
 	temperature_adc_init();
+	dmx_init(0u);
 
 	SysTick_Config(800000);
 	while(1) {
@@ -171,11 +173,16 @@ int main(void)
 		}
 
 		TIM14->CCR1 = led_pwm_val;
-		__disable_irq();
+
 		for(int i = 0; i < RING_MAX_LED; i ++) {
+			/* Allow interrupts in between LEDs.
+			 * They must not exceed the reset length of 80us of SK6812.
+			 */
+			__disable_irq();
 			sk6812_send_led(led_calc_val[i]);
-		}
 			__enable_irq();
+		}
+
 		wait_for_ticks(5);
 
 		if((int16_t)TIM3->CNT > (int16_t)led_val) {