Force the use of system's reset in openocd

Using the system's reset avoids the debug getting stuck when the chip
enters low power. Hopefully this works all the time

drv/bkp.c

@@ -1,6 +1,11 @@
 /** @file bkp.c
  * Module handling the Backup (BKP) domain functionalities.
  *
+ * This module includes management of the Real Time Clock (RTC), Tamper
+ * protection system and a limited space (20 bytes) for persistent data storage
+ *
+ * All features present in this module stay running in standby mode / when
+ * no-longer powered, so long as VBAT is maintained
  */
 
 //--includes--------------------------------------------------------------------
@@ -28,7 +33,7 @@ static BkpRtcCallback rtc_callback;
 //--public functions------------------------------------------------------------
 
 void bkp_configure_rtc(uint32_t period_ms, enum BkpRtcClockSrc clock_src,
-		enum BkpRtcIrq irq_mask, uint32_t alarm_tick, BkpRtcCallback callback)
+		enum BkpRtcIrq irq_mask, BkpRtcCallback callback)
 {
 	rcc_enable(RCC_AHB_NONE, RCC_APB1_BKP, RCC_APB2_NONE);
 
@@ -50,8 +55,6 @@ void bkp_configure_rtc(uint32_t period_ms, enum BkpRtcClockSrc clock_src,
 	//configure core registers
 	rtc_regs->PRLH.PRL = prescaler >> 16;
 	rtc_regs->PRLL.PRL = prescaler;
-	rtc_regs->ALRH.RTC_ALR = alarm_tick >> 16;
-	rtc_regs->ALRL.RTC_ALR = alarm_tick;
 
 	//apply irq config
 	rtc_regs->CRH.word |= irq_mask & 0x7;
@@ -68,6 +71,27 @@ void bkp_configure_rtc(uint32_t period_ms, enum BkpRtcClockSrc clock_src,
 	}
 }
 
+void bkp_set_rtc_alam(uint32_t offset)
+{
+	uint32_t alarm = bkp_read_rtc() + offset;
+
+	//wait for last operation to finish
+	while (rtc_regs->CRL.RTOFF != 1) {}
+
+	//enable core configuration
+	rtc_regs->CRL.CNF = 1;
+
+	//write alarm value
+	rtc_regs->ALRH.RTC_ALR = alarm >> 16;
+	rtc_regs->ALRL.RTC_ALR = alarm;
+
+	//disable/apply core configuration
+	rtc_regs->CRL.CNF = 0;
+
+	//wait for last operation to finish
+	while (rtc_regs->CRL.RTOFF != 1) {}
+}
+
 uint32_t bkp_read_rtc(void)
 {
 	//wait for core registers to be synchronized, immediate most of the time

drv/bkp.h

@@ -1,6 +1,11 @@
 /** @file bkp.h
  * Module handling the Backup (BKP) domain functionalities.
  *
+ * This module includes management of the Real Time Clock (RTC), Tamper
+ * protection system and a limited space (20 bytes) for persistent data storage
+ *
+ * All features present in this module stay running in standby mode / when
+ * no-longer powered, so long as VBAT is maintained
  */
 
 #ifndef _BKP_H_
@@ -58,11 +63,23 @@ typedef void (*BkpRtcCallback)(enum BkpRtcIrq src);
  * Clocks must be enabled prior to calling this function
  *
  * Mulitple IRQs can be enabled and redirected to single callback. The alarm
- * IRQ, triggered at the specified tick value can be rerouted to an exti line
- * for wakeup from stanby, in wich case it doesn't need to be enabled here.
+ * IRQ, triggered at the tick value specified by bkp_set_rtc_alam() can be
+ * rerouted to an exti line for wakeup from stop and standby, in wich case it
+ * doesn't need to be enabled here.
+ *
+ * Ensure backup domain writes are enabled (see pwr_configure_bkp_write()) while
+ * calling this function
  */
 void bkp_configure_rtc(uint32_t period_ms, enum BkpRtcClockSrc clock_src,
-		enum BkpRtcIrq irq_mask, uint32_t alarm_tick, BkpRtcCallback callback);
+		enum BkpRtcIrq irq_mask, BkpRtcCallback callback);
+
+/**
+ * Configure the alarm to trigger after the specified time in ticks, which can
+ * be viewed as an offset to the current time value. This offset is only precise
+ * to the tick and thus if the tick changes right after this function is
+ * called, the observed offset will be close to 1 tick short
+ */
+void bkp_set_rtc_alam(uint32_t offset);
 
 /**
  * Returns the current counter value of the RTC

drv/exti.c

@@ -11,7 +11,6 @@
 #include "exti_regs.h"
 
 #include "nvic.h"
-#include "afio.h"
 
 
 //--local definitions-----------------------------------------------------------
@@ -24,13 +23,11 @@ static ExtiCallback callbacks[19];
 
 //--public functions------------------------------------------------------------
 
-void exti_configure(enum ExtiLine line_mask, enum GpioPort port,
-		enum ExtiConfig config_mask, ExtiCallback callback)
+void exti_configure(enum ExtiLine line_mask, enum ExtiConfig config_mask,
+		ExtiCallback callback)
 {
 	exti_reset(line_mask);
 
-	afio_map_exti(line_mask, port);
-
 	//configure edge detections
 	if (config_mask & EXTI_CONFIG_RISING_EDGE) {
 		regs->RTSR.word |= line_mask;
@@ -48,7 +45,7 @@ void exti_configure(enum ExtiLine line_mask, enum GpioPort port,
 	regs->EMR.word |= line_mask;
 	if (callback) {
 		//register callbacks for each line selected
-		for (uint8_t i = 0; i < 16;  ++i) {
+		for (uint8_t i = 0; i < 19;  ++i) {
 			if (line_mask & (0x1 << i)) {
 				callbacks[i] = callback;
 			}
@@ -66,6 +63,15 @@ void exti_configure(enum ExtiLine line_mask, enum GpioPort port,
 		if (line_mask & 0x7c00) {
 			nvic_enable(NVIC_IRQ_EXTI15_10);
 		}
+		if (line_mask & EXTI_LINE_PVD) {
+			nvic_enable(NVIC_IRQ_PVD);
+		}
+		if (line_mask & EXTI_LINE_RTC) {
+			nvic_enable(NVIC_IRQ_RTC_ALARM);
+		}
+		if (line_mask & EXTI_LINE_USB) {
+			nvic_enable(NVIC_IRQ_USB_WAKEUP);
+		}
 
 		//enable irqs in last to avoid triggers during config
 		regs->IMR.word |= line_mask;
@@ -94,56 +100,6 @@ void exti_reset(enum ExtiLine line_mask)
 		nvic_disable(NVIC_IRQ_EXTI15_10);
 	}
 
-	afio_map_exti(0xFFFF, 0x0);
-}
-
-void exti_configure_specific(enum ExtiLineSpecific line_mask,
-		enum ExtiConfig config_mask, ExtiCallback callback)
-{
-	//reset is identical to normal lines
-	exti_reset_specific(line_mask);
-
-	//configure edge detections
-	if (config_mask & EXTI_CONFIG_RISING_EDGE) {
-		regs->RTSR.word |= line_mask;
-	} else {
-		regs->RTSR.word &= ~line_mask;
-	}
-
-	if (config_mask & EXTI_CONFIG_FALLING_EDGE) {
-		regs->FTSR.word |= line_mask;
-	} else {
-		regs->FTSR.word &= ~line_mask;
-	}
-
-	//reconfigure events/irqs
-	regs->EMR.word |= line_mask;
-	if (callback) {
-		//register callbacks for each line selected
-		for (uint8_t i = 0; i < 16;  ++i) {
-			if (line_mask & (0x1 << i)) {
-				callbacks[i] = callback;
-			}
-		}
-
-		//enable interrupts lines in nvic
-		if (line_mask & EXTI_LINE_PVD) {
-			nvic_enable(NVIC_IRQ_PVD);
-		}
-		if (line_mask & EXTI_LINE_RTC) {
-			nvic_enable(NVIC_IRQ_RTC_ALARM);
-		}
-		if (line_mask & EXTI_LINE_USB) {
-			nvic_enable(NVIC_IRQ_USB_WAKEUP);
-		}
-
-		//enable irqs in last to avoid triggers during config
-		regs->IMR.word |= line_mask;
-	}
-}
-
-void exti_reset_specific(enum ExtiLineSpecific line_mask)
-{
 	//disable events/irqs
 	regs->IMR.word &= ~line_mask;
 	regs->EMR.word &= ~line_mask;
@@ -163,6 +119,7 @@ void exti_reset_specific(enum ExtiLineSpecific line_mask)
 	}
 }
 
+
 void exti_reset_peripheral(void)
 {
 	//reset peripheral config
@@ -182,8 +139,6 @@ void exti_reset_peripheral(void)
 	nvic_disable(NVIC_IRQ_PVD);
 	nvic_disable(NVIC_IRQ_RTC_ALARM);
 	nvic_disable(NVIC_IRQ_USB_WAKEUP);
-
-	afio_map_exti(0xFFFF, 0x0);
 }
 
 //--local functions-------------------------------------------------------------

drv/exti.h

@@ -10,16 +10,11 @@
 
 //--includes--------------------------------------------------------------------
 
-#include "stdint.h"
-#include "stdbool.h"
-
-#include "gpio.h"
-
-
 //--type definitions------------------------------------------------------------
 
 /**
- * Available exti lines. These lines correspond to gpios
+ * Available exti lines. The numbered lines correspond to gpios while the
+ * remaining are directly mapped to peripherals
  */
 enum ExtiLine {
 	EXTI_LINE_0  = (0x1 <<  0),
@@ -38,12 +33,6 @@ enum ExtiLine {
 	EXTI_LINE_13 = (0x1 << 13),
 	EXTI_LINE_14 = (0x1 << 14),
 	EXTI_LINE_15 = (0x1 << 15),
-};
-
-/**
- * Available exti lines. These lines correspond to specific peripherals
- */
-enum ExtiLineSpecific {
 	EXTI_LINE_PVD = (0x1 << 16),
 	EXTI_LINE_RTC = (0x1 << 17),
 	EXTI_LINE_USB = (0x1 << 18),
@@ -64,43 +53,31 @@ typedef void (*ExtiCallback)(void);
 //--functions-------------------------------------------------------------------
 
 /**
- * Configure lines on a single GPIO port. The ExtiLine enum can be used as a
- * mask to configure multiple lines at the same time. Every line can only be
- * configured for a single port, reconfiguring it will override the previous
- * configuration. Each line is linked to the pins of the same id (ex : pin 1 for
- * exti 1). When possible, it is recommanded to use the lowest id possible for
- * better performance. The ExtiConfig enum can be used as mask. If no callback
- * is specified, the interrupt won't be enabled, but an event will still be sent
- * to wake the cpu up.
+ * Configure lines to call a single callback. The ExtiLine enum can be used as a
+ * mask to configure multiple lines at the same time.
  *
- * Note: wich port is linked to a line can be changed atfer the fact using
- * afio_map_exti()
+ * Every numbered line must be linked to a gpio port using afio_map_exti(). Each
+ * line is linked to the pins of the same id (ex : pin 1 for exti 1). When
+ * possible, it is recommended to use the lowest id possible for better
+ * performance. Each pin must be configured independently through the gpio
+ * driver module
+ *
+ * The remaining lines are linked to specific peripherals which must be
+ * configured independently through the corresponding driver module.
+ *
+ * The ExtiConfig enum can be used as mask. If no callback is specified, the
+ * interrupt won't be enabled, but an event will still be sent to wake the cpu
+ * up.
  */
-void exti_configure(enum ExtiLine line_mask, enum GpioPort port,
-		enum ExtiConfig config_mask, ExtiCallback callback);
+void exti_configure(enum ExtiLine line_mask, enum ExtiConfig config_mask,
+		ExtiCallback callback);
 
 /**
- * Resets lines. The ExtiLine enum can be used as a mask to configure multiple
- * lines at the same time
+ * Resets lines. The ExtiLine enum can be used as a mask to reset multiple lines
+ * at the same time
  */
 void exti_reset(enum ExtiLine line_mask);
 
-/**
- * Configure lines for specific, non-gpio peripherals. The ExtiLineSpecific enum
- * can be used as a mask to configure multiple lines at the same time. The
- * ExtiConfig enum can be used as mask. If no callback is specified, the
- * interrupt won't be enabled, but an event will still be sent to wake the cpu
- * up
- */
-void exti_configure_specific(enum ExtiLineSpecific line_mask,
-		enum ExtiConfig config_mask, ExtiCallback callback);
-
-/**
- * Resets lines for specific, non-gpio peripherals. The ExtiLineSpecific enum
- * can be used as a mask to configure multiple lines at the same time.
- */
-void exti_reset_specific(enum ExtiLineSpecific line_mask);
-
 /**
  * Resets all lines. The exti peripheral is returned to its reset configuration
  */

openocd.cfg

@@ -0,0 +1,25 @@
+
+# using a STM32f103CB wich has 128kB of flash instead of the more common 64KB
+set CHIPNAME stm32f103CB
+set FLASH_SIZE 0x20000
+
+# load default configurations
+source [find interface/stlink.cfg]
+source [find target/stm32f1x.cfg]
+
+# override examine-end event
+$CHIPNAME.cpu configure -event examine-end {
+	# write DBGMCU_CR, disable all peripherals (timers, dmas, watchdogs while
+	# halted by debug. Trace is not affected
+	mmw 0xE0042004 0x7E3FFF07 0
+}
+
+
+reset_config srst_only srst_nogate connect_assert_srst
+
+# inits debugging, from that point, commands can be used
+init
+# resets the target and halt it immediately afterward. Stops debug from being
+# inacessible due to low-power states
+reset halt
+

srv/task.c

@@ -26,6 +26,10 @@
 #include "task.h"
 #include "error.h"
 #include "../drv/stk.h"
+#include "../drv/pwr.h"
+#include "../drv/rcc.h"
+#include "../drv/bkp.h"
+#include "../drv/exti.h"
 
 
 //--local definitions-----------------------------------------------------------
@@ -51,7 +55,13 @@ static volatile uint32_t timestamp;
 void task_start_scheduler(void)
 {
 	stk_configure(1000, callback_stk);
-	//TODO: configure RTC
+
+	rcc_configure_lsi(true);
+	pwr_configure_bkp_write(true);
+	bkp_reset();
+	bkp_configure_rtc(1000, BKP_RTC_CLOCK_SRC_LSI, BKP_RTC_IRQ_NONE, nullptr);
+	pwr_configure_bkp_write(false);
+	exti_configure(EXTI_LINE_RTC, EXTI_CONFIG_RISING_EDGE, callback_rtc);
 
 	while (true) {
 		uint8_t triggers = stk_irq << 0 | rtc_irq << 1;
@@ -65,10 +75,13 @@ void task_start_scheduler(void)
 
 		if (stk_needed) {
 			stk_start();
-			__asm("wfi");
+			pwr_sleep();
 		} else {
+			pwr_configure_bkp_write(true);
+			bkp_set_rtc_alam(1);
+			pwr_configure_bkp_write(false);
 			stk_stop();
-			//TODO: enter deep sleep
+			pwr_sleep();
 		}
 	}
 }
@@ -158,4 +171,5 @@ static void callback_stk(void)
 static void callback_rtc(void)
 {
 	rtc_irq = true;
+	timestamp = bkp_read_rtc() * 1000;
 }