drivers/rtt_rtc: add option to not attempt to retain time across reboots

[benpicco]

Contribution description

This can be error prone if no backup RAM is available. When keeping multiple sensors in sync, it can be more desirable to let them all start at 0 (when powered on at the same time) than some random time when using the .noinit section.

Testing procedure

Issues/PRs references

[fjmolinas]

Can you provide a test procudure and output?

[fabian18]

Can you provide a test procudure and output?

diff --git a/cpu/samd5x/periph/pm.c b/cpu/samd5x/periph/pm.c
index e06b3c6dd6..67ef1c980d 100644
--- a/cpu/samd5x/periph/pm.c
+++ b/cpu/samd5x/periph/pm.c
@@ -21,7 +21,7 @@
 
 #include "periph/pm.h"
 
-#define ENABLE_DEBUG 0
+#define ENABLE_DEBUG 1
 #include "debug.h"
 
 void pm_set(unsigned mode)
diff --git a/examples/default/Makefile b/examples/default/Makefile
index 467c36f3f8..d462470efc 100644
--- a/examples/default/Makefile
+++ b/examples/default/Makefile
@@ -49,7 +49,8 @@ ifneq (,$(filter $(BOARD),$(BOARD_PROVIDES_NETIF)))
   USEMODULE += gnrc_pktdump
 endif
 
-FEATURES_OPTIONAL += periph_rtc
+#FEATURES_OPTIONAL += periph_rtc
+FEATURES_OPTIONAL += periph_rtt
 
 ifneq (,$(filter msba2,$(BOARD)))
   USEMODULE += mci
diff --git a/sys/shell/commands/Makefile b/sys/shell/commands/Makefile
index eeddbbbb07..73b53f607e 100644
--- a/sys/shell/commands/Makefile
+++ b/sys/shell/commands/Makefile
@@ -110,6 +110,12 @@ ifneq (,$(filter periph_rtc,$(USEMODULE)))
   SRC += sc_rtc.c
 endif
 
+ifneq (,$(filter periph_rtt,$(USEMODULE)))
+  ifneq (,$(filter rtt_rtc,$(USEMODULE)))
+    SRC += sc_rtc.c
+  endif
+endif
+
 ifneq (,$(filter rtt_cmd,$(USEMODULE)))
   SRC += sc_rtt.c
 endif
diff --git a/sys/shell/commands/shell_commands.c b/sys/shell/commands/shell_commands.c
index 33a948a4d2..890c70e418 100644
--- a/sys/shell/commands/shell_commands.c
+++ b/sys/shell/commands/shell_commands.c
@@ -64,7 +64,7 @@ extern int _at30tse75x_handler(int argc, char **argv);
 extern int _saul(int argc, char **argv);
 #endif
 
-#ifdef MODULE_PERIPH_RTC
+#if defined(MODULE_PERIPH_RTC) || (defined(MODULE_PERIPH_RTT) && defined(MODULE_RTT_RTC))
 extern int _rtc_handler(int argc, char **argv);
 #endif
 
@@ -262,7 +262,7 @@ const shell_command_t _shell_command_list[] = {
     { "random_init", "initializes the PRNG", _random_init },
     { "random_get", "returns 32 bit of pseudo randomness", _random_get },
 #endif
-#ifdef MODULE_PERIPH_RTC
+#if defined(MODULE_PERIPH_RTC) || (defined(MODULE_PERIPH_RTT) && defined(MODULE_RTT_RTC))
     {"rtc", "control RTC peripheral interface",  _rtc_handler},
 #endif
 #ifdef MODULE_RTT_CMD
(END)

USEMODULE+=rtt_rtc CFLAGS+=-DCONFIG_RTT_RTC_NO_RETAIN=1 BOARD=same54-xpro make -C examples/default flash term

rtc gettime
rtc setalarm  2024-01-01 00:01:00
rtc settime 2024-01-01 00:00:00
pm set 0

2023-12-31 15:15:05,622 # rtc gettime
2023-12-31 15:15:05,624 # 2020-01-01 00:00:01
> 2023-12-31 15:15:05,626 # pm_set(): setting IDLE2 mode.
rtc setalarm  2024-01-01 00:01:00
2023-12-31 15:15:15,521 # rtc setalarm  2024-01-01 00:01:00
> 2023-12-31 15:15:15,524 # pm_set(): setting IDLE2 mode.
rtc settime 2024-01-01 00:00:00
2023-12-31 15:15:19,952 # rtc settime 2024-01-01 00:00:00
> 2023-12-31 15:15:19,955 # pm_set(): setting IDLE2 mode.
pm set 0
2023-12-31 15:15:23,487 # pm set 0
2023-12-31 15:15:23,490 # CPU is entering power mode 0.
2023-12-31 15:15:23,493 # Now waiting for a wakeup event...
2023-12-31 15:15:23,496 # pm_set(): setting BACKUP mode.
2023-12-31 15:16:19,973 # NETOPT_RX_END_IRQ not implemented by driver
2023-12-31 15:16:19,979 # main(): This is RIOT! (Version: 2022.04-devel-805-g72c7ac-HEAD)
2023-12-31 15:16:19,980 # Welcome to RIOT!
> 2023-12-31 15:16:19,983 # pm_set(): setting IDLE2 mode.
rtc gettime
2023-12-31 15:16:25,641 # rtc gettime
2023-12-31 15:16:25,643 # 2020-01-01 00:00:05
> 2023-12-31 15:16:25,646 # pm_set(): setting IDLE2 mode.

USEMODULE+=rtt_rtc CFLAGS+=-DCONFIG_RTT_RTC_NO_RETAIN=0 BOARD=same54-xpro make -C examples/default flash term

rtc gettime
rtc setalarm  2024-01-01 00:01:00
rtc settime 2024-01-01 00:00:00
pm set 0

2023-12-31 15:17:36,525 # rtc gettime
2023-12-31 15:17:36,527 # 2020-01-01 00:00:05
> 2023-12-31 15:17:36,530 # pm_set(): setting IDLE2 mode.
rtc setalarm  2024-01-01 00:01:00
2023-12-31 15:17:41,918 # rtc setalarm  2024-01-01 00:01:00
> 2023-12-31 15:17:41,921 # pm_set(): setting IDLE2 mode.
rtc settime 2024-01-01 00:00:00
2023-12-31 15:17:46,450 # rtc settime 2024-01-01 00:00:00
> 2023-12-31 15:17:46,453 # pm_set(): setting IDLE2 mode.
pm set 0
2023-12-31 15:17:50,592 # pm set 0
2023-12-31 15:17:50,594 # CPU is entering power mode 0.
2023-12-31 15:17:50,597 # Now waiting for a wakeup event...
2023-12-31 15:17:50,600 # pm_set(): setting BACKUP mode.
2023-12-31 15:18:46,472 # NETOPT_RX_END_IRQ not implemented by driver
2023-12-31 15:18:46,477 # main(): This is RIOT! (Version: 2022.04-devel-805-g72c7ac-HEAD)
2023-12-31 15:18:46,479 # Welcome to RIOT!
> 2023-12-31 15:18:46,482 # pm_set(): setting IDLE2 mode.
rtc gettime
2023-12-31 15:18:49,848 # rtc gettime
2023-12-31 15:18:49,850 # 2024-01-02 12:24:20
> 2023-12-31 15:18:49,853 # pm_set(): setting IDLE2 mode.

[fabian18]

2023-12-31 15:18:49,850 # 2024-01-02 12:24:20

That's a bit unexpected that it is about one and a half days in the future. But executing rtc gettime again returns the correct time.

rtc gettime
2023-12-31 15:57:25,367 # rtc gettime
2023-12-31 15:57:25,369 # 2024-01-01 00:01:49
> 2023-12-31 15:57:25,372 # pm_set(): setting IDLE2 mode.