bmp-v3: Implemented logic for enabling and disabling the secondary UART appropriately based on state changes

Author: dragonmux

src/include/platform_support.h

@@ -85,10 +85,18 @@ const char *platform_ident(void);
 #endif
 
 #ifdef PLATFORM_MULTI_UART
+typedef enum uart_state {
+	UART_STATE_UNKNOWN,
+	UART_STATE_IDLE,
+	UART_STATE_LOST,
+} uart_state_e;
+
 void platform_enable_uart2(void);
 void platform_disable_uart2(void);
 bool platform_is_uart2_enabled(void);
 void platform_switch_dir_uart2(void);
+void platform_uart2_state_change(uint32_t state);
+uart_state_e platform_uart2_state(void);
 #endif
 
 #endif /* INCLUDE_PLATFORM_SUPPORT_H */

src/platforms/bmp-v3/platform.c

@@ -59,6 +59,8 @@ static void adc_init(void);
 
 int hwversion = -1;
 
+static uart_state_e uart2_state = UART_STATE_UNKNOWN;
+
 void platform_init(void)
 {
 	hwversion = 0;
@@ -454,8 +456,9 @@ void platform_enable_uart2(void)
 
 void platform_disable_uart2(void)
 {
-	/* Dsiable the UART (so we can go back into being able to change the pin swapping) */
+	/* Disable the UART (so we can go back into being able to change the pin swapping) */
 	usart_disable(AUX_UART2);
+	uart2_state = UART_STATE_UNKNOWN;
 	/* Reconfigure the GPIOs back to inputs so we can listen for which is high to watch for new connections */
 	gpio_mode_setup(AUX_UART2_PORT, GPIO_MODE_INPUT, GPIO_PUPD_NONE, AUX_UART2_TX_PIN | AUX_UART2_RX_PIN);
 }
@@ -470,3 +473,17 @@ void platform_switch_dir_uart2(void)
 	/* Swap the directions of the BMPU connector UART pins */
 	gpio_toggle(AUX_UART2_DIR_PORT, AUX_UART2_DIR_PIN);
 }
+
+void platform_uart2_state_change(const uint32_t state)
+{
+	/* Make a note of whether either Idle or Framing Error have occured */
+	if (state & USART_ISR_IDLE)
+		uart2_state = UART_STATE_IDLE;
+	else if (state & USART_ISR_FE)
+		uart2_state = UART_STATE_LOST;
+}
+
+uart_state_e platform_uart2_state(void)
+{
+	return uart2_state;
+}

src/platforms/common/aux_serial.c

@@ -633,6 +633,10 @@ static void aux_serial_receive_isr(const uintptr_t uart, const uint8_t dma_irq)
 		debug_serial_run();
 	}
 
+#ifdef PLATFORM_MULTI_UART
+	if (uart == AUX_UART2)
+		platform_uart2_state_change(status);
+#endif
 #ifndef STM32U5
 	nvic_enable_irq(dma_irq);
 #else
@@ -819,6 +823,7 @@ void aux_uart2_rx_detect_isr(void)
 	 * UART2 just became active, so bring it up and disable the EXTI for it, making sure UART1's is
 	 * active in case the user swaps UARTs over
 	 */
+	platform_enable_uart2();
 	aux_serial_activate_uart(AUX_UART2);
 	exti_reset_request(AUX_UART2_RX_DETECT_EXTI);
 	exti_disable_request(AUX_UART2_RX_DETECT_EXTI);

src/platforms/common/stm32/timing_stm32.c

@@ -160,8 +160,23 @@ void sys_tick_handler(void)
 			/* And reset the counter back to 0 */
 			uart_ticks = 0U;
 		}
-	} else
-		uart_ticks = 0U;
+	} else {
+		/*
+		 * If the UART goes into framing error and that persists for more than a milisecond or two, then
+		 * it's probably safe to assume that the wires became disconnected and the UART is no longer active
+		 * in which case we then want to disable the UART and go back into swap scanning. Additionally, we'll
+		 * want to either make the other UART active, or make all UARTs inactive.
+		 */
+		const uart_state_e state = platform_uart2_state();
+		if (state == UART_STATE_LOST) {
+			if (++uart_ticks == 2U) {
+				platform_disable_uart2();
+				uart_ticks = 0U;
+			}
+		} else
+			/* Otherwise if the UART state is either not known or the UART is idle, reset the tick counter */
+			uart_ticks = 0U;
+	}
 #endif
 }