Enable serial port only when tag reset is externally triggered

- use the reset reason to decide whether to enable UART and log to it
- streamline the high-speed/low-speed serial baud rate selection

Author: ccattuto

firmware/nRF51/core/openbeacon/inc/uart.h

@@ -35,7 +35,6 @@
 
 #ifdef CONFIG_UART_BAUDRATE
 extern void uart_init(void);
-extern int uart_enable(int enable);
 extern BOOL uart_tx(uint8_t data);
 extern int uart_rx(void);
 #endif

firmware/nRF51/core/openbeacon/src/uart.c

@@ -34,6 +34,7 @@ static volatile uint16_t g_uart_buffer_count;
 /* allow to override default putchar output from serial to something else */
 BOOL default_putchar (uint8_t data) ALIAS(uart_tx);
 
+
 void uart_init(void)
 {
 	g_uart_buffer_count = 0;
@@ -74,21 +75,17 @@ void uart_init(void)
 		(UART_INTENSET_TXDRDY_Enabled << UART_INTENSET_TXDRDY_Pos);
 
 	/* start UART */
-#ifdef  CONFIG_UART_RXD_PIN
+
+#if CONFIG_UART_FORCE_POWERED | CONFIG_UART_RXD_PIN
 	NRF_UART0->ENABLE = (UART_ENABLE_ENABLE_Enabled << UART_ENABLE_ENABLE_Pos);
-	NRF_UART0->TASKS_STARTRX = 1;
-	NRF_UART0->EVENTS_RXDRDY = 0;
 #else
 	NRF_UART0->ENABLE = 0;
-#endif /*CONFIG_UART_RXD_PIN*/
-}
+#endif
 
-inline int uart_enable(int enable)
-{
-#if CONFIG_UART_FORCE_POWERED
-	NRF_UART0->ENABLE = (enable) ? (NRF_UART0->ENABLE = UART_ENABLE_ENABLE_Enabled << UART_ENABLE_ENABLE_Pos) : 0;
+#ifdef CONFIG_UART_RXD_PIN
+	NRF_UART0->TASKS_STARTRX = 1;
+	NRF_UART0->EVENTS_RXDRDY = 0;
 #endif
-	return enable;
 }
 
 #ifdef  CONFIG_UART_TXD_PIN
@@ -111,7 +108,9 @@ BOOL uart_tx(uint8_t data)
 	else
 	{
 		/* enable UART for sending out first byte */
+#if !CONFIG_UART_FORCE_POWERED
 		NRF_UART0->ENABLE = (UART_ENABLE_ENABLE_Enabled << UART_ENABLE_ENABLE_Pos);
+#endif
 		NRF_UART0->TASKS_STARTTX = 1;
 		NRF_UART0->TXD = data;
 	}

firmware/nRF51/tag-proximity/src/main.c

@@ -25,6 +25,7 @@
 */
 
 #include <openbeacon.h>
+#include <uart.h>
 #include <acc.h>
 #include <flash.h>
 #include <radio.h>
@@ -38,6 +39,7 @@ uint8_t hibernate = 0;
 uint16_t status_flags = 0;
 uint8_t boot_count;
 uint32_t reset_reason;
+uint8_t uart_enabled = 0;
 
 
 void blink(uint8_t times)
@@ -99,10 +101,14 @@ void main_entry(void)
 	reset_reason = NRF_POWER->RESETREAS;
 	NRF_POWER->RESETREAS = 0;
 
-	/* if reset was externally triggered, boot into hibernation mode */
+	/* if reset was externally triggered,
+	   boot into hibernation mode and enable serial port */
 	if ( (reset_reason & POWER_RESETREAS_RESETPIN_Msk) ||
 		 (reset_reason & POWER_RESETREAS_SREQ_Msk) )
+	{
 		hibernate = 1;
+		uart_enabled = 1;
+	}
 
 	/* get/update boot counter -- register is retained
 	   across resets as long as the device is powered */
@@ -121,7 +127,6 @@ void main_entry(void)
 
 	/* initialize UART */
 	uart_init();
-	uart_enable(1);
 
 	/* start timer */
 	timer_init();
@@ -142,13 +147,12 @@ void main_entry(void)
 		halt(3);
 
 	/* start radio */
-	debug_printf("\n\rInitializing Tag[%08X] v" PROGRAM_VERSION " @24%02iMHz ...\n\r",
+	if (uart_enabled)
+		debug_printf("\n\rInitializing Tag[%08X] v" PROGRAM_VERSION " @24%02iMHz ...\n\r",
 		tag_id,
 		CONFIG_TRACKER_CHANNEL);
 	radio_init(tag_id);
 
-	uart_enable(0);
-
 	/* enter main loop */
 	blink_fast(5);
 
@@ -172,16 +176,14 @@ void main_entry(void)
 			keypress_duration = blink_wait_release();
 
 			/* long key press while tag is hibernating triggers log dump */
-			if (hibernate && (keypress_duration > 2000))
+			if (hibernate && uart_enabled && (keypress_duration > 2000))
 			{
 #if CONFIG_FLASH_LOGGING
 				blink_fast(10);
 
 				/* dump log data & status to serial */
-				uart_enable(1);
 				flash_log_dump();
 				flash_log_status();
-				uart_enable(0);
 #endif /* CONFIG_FLASH_LOGGING */
 			} else if (keypress_duration > 500)
 			{
@@ -195,9 +197,8 @@ void main_entry(void)
 #endif /* CONFIG_FLASH_LOGGING */
 
 				blink_fast(hibernate ? 3 : 6);
-				uart_enable(1);
-				debug_printf("\n\rhibernate -> %i", hibernate);
-				uart_enable(0);
+				if (uart_enabled)
+					debug_printf("\n\rhibernate -> %i", hibernate);
 			}
 		}