Merge pull request #745 from notro/time_rtc

RFC: Add rtc module

20 files changed, 624 insertions, 24 deletions

diff --git a/ports/atmel-samd/Makefile b/ports/atmel-samd/Makefile
index 2f01abc4f..6b661cd84 100644
--- a/ports/atmel-samd/Makefile
+++ b/ports/atmel-samd/Makefile
@@ -39,6 +39,7 @@ INC += -I. \
        -Iasf4/$(CHIP_FAMILY)/hpl/gclk \
        -Iasf4/$(CHIP_FAMILY)/hpl/pm \
        -Iasf4/$(CHIP_FAMILY)/hpl/port \
+       -Iasf4/$(CHIP_FAMILY)/hpl/rtc \
        -Iasf4/$(CHIP_FAMILY)/hpl/tc \
        -Iasf4/$(CHIP_FAMILY)/include \
        -Iasf4/$(CHIP_FAMILY)/CMSIS/Include \
@@ -173,6 +174,7 @@ SRC_ASF := \
 	gcc/system_$(CHIP_FAMILY).c \
 	hal/src/hal_adc_sync.c \
 	hal/src/hal_atomic.c \
+	hal/src/hal_calendar.c \
 	hal/src/hal_dac_sync.c \
 	hal/src/hal_delay.c \
 	hal/src/hal_flash.c \
@@ -278,6 +280,8 @@ SRC_COMMON_HAL = \
 	microcontroller/Processor.c \
 	neopixel_write/__init__.c \
 	os/__init__.c \
+	rtc/__init__.c \
+	rtc/RTC.c \
 	storage/__init__.c \
 	supervisor/__init__.c \
 	supervisor/Runtime.c \
diff --git a/ports/atmel-samd/asf4 b/ports/atmel-samd/asf4
-Subproject aaa0f428111fbea7d56ab548053b11c9f12068f
+Subproject 02e264253c76b85c567ecdfce69ad0de0970da6
diff --git a/ports/atmel-samd/asf4_conf/samd21/hpl_gclk_config.h b/ports/atmel-samd/asf4_conf/samd21/hpl_gclk_config.h
index d4c9bf2ab..230f6e618 100644
--- a/ports/atmel-samd/asf4_conf/samd21/hpl_gclk_config.h
+++ b/ports/atmel-samd/asf4_conf/samd21/hpl_gclk_config.h
@@ -190,7 +190,7 @@
 // <i> Indicates whether generic clock 2 configuration is enabled or not
 // <id> enable_gclk_gen_2
 #ifndef CONF_GCLK_GENERATOR_2_CONFIG
-#define CONF_GCLK_GENERATOR_2_CONFIG 0
+#define CONF_GCLK_GENERATOR_2_CONFIG 1
 #endif
 
 // <h> Generic Clock Generator Control
@@ -205,7 +205,7 @@
 // <i> Indicates whether Divide Selection is enabled or not
 // <id> gclk_gen_2_div_sel
 #ifndef CONF_GCLK_GEN_2_DIVSEL
-#define CONF_GCLK_GEN_2_DIVSEL 0
+#define CONF_GCLK_GEN_2_DIVSEL 1
 #endif
 
 // <q> Output Enable
@@ -233,7 +233,7 @@
 // <i> Indicates whether Generic Clock Generator Enable is enabled or not
 // <id> gclk_arch_gen_2_enable
 #ifndef CONF_GCLK_GEN_2_GENEN
-#define CONF_GCLK_GEN_2_GENEN 0
+#define CONF_GCLK_GEN_2_GENEN 1
 #endif
 
 // <y> Generic clock generator 2 source
@@ -259,7 +259,7 @@
 // <i> This defines the clock source for generic clock generator 2
 // <id> gclk_gen_2_oscillator
 #ifndef CONF_GCLK_GEN_2_SRC
-#define CONF_GCLK_GEN_2_SRC GCLK_GENCTRL_SRC_OSC32K
+#define CONF_GCLK_GEN_2_SRC GCLK_GENCTRL_SRC_XOSC32K
 #endif
 // </h>
 
@@ -268,7 +268,7 @@
 // <i>
 // <id> gclk_gen_2_div
 #ifndef CONF_GCLK_GEN_2_DIV
-#define CONF_GCLK_GEN_2_DIV 1
+#define CONF_GCLK_GEN_2_DIV 4
 #endif
 
 // </h>
diff --git a/ports/atmel-samd/asf4_conf/samd21/hpl_rtc_config.h b/ports/atmel-samd/asf4_conf/samd21/hpl_rtc_config.h
index 929c70c8c..7b77d9031 100644
--- a/ports/atmel-samd/asf4_conf/samd21/hpl_rtc_config.h
+++ b/ports/atmel-samd/asf4_conf/samd21/hpl_rtc_config.h
@@ -10,6 +10,14 @@
 #define CONF_RTC_ENABLE 1
 #endif
 
+// <q> Force reset RTC on initialization
+// <i> Force RTC to reset on initialization, else init is not going on if RTC is already enabled.
+// <i> Note that the previous power down data in RTC is lost if it's enabled.
+// <id> rtc_arch_init_reset
+#ifndef CONF_RTC_INIT_RESET
+#define CONF_RTC_INIT_RESET 0
+#endif
+
 // <o> Prescaler configuration
 // <0x0=>Peripheral clock divided by 1
 // <0x1=>Peripheral clock divided by 2
@@ -25,7 +33,7 @@
 // <i> These bits define the RTC clock relative to the peripheral clock
 // <id> rtc_arch_prescaler
 #ifndef CONF_RTC_PRESCALER
-#define CONF_RTC_PRESCALER 0x0
+#define CONF_RTC_PRESCALER 0xa
 
 #endif
 
diff --git a/ports/atmel-samd/asf4_conf/samd21/hpl_sysctrl_config.h b/ports/atmel-samd/asf4_conf/samd21/hpl_sysctrl_config.h
index 389aefff3..eaec93811 100644
--- a/ports/atmel-samd/asf4_conf/samd21/hpl_sysctrl_config.h
+++ b/ports/atmel-samd/asf4_conf/samd21/hpl_sysctrl_config.h
@@ -197,7 +197,7 @@
 // <i> Indicates whether configuration for External 32K Osc is enabled or not
 // <id> enable_xosc32k
 #ifndef CONF_XOSC32K_CONFIG
-#define CONF_XOSC32K_CONFIG 0
+#define CONF_XOSC32K_CONFIG 1
 #endif
 
 // <h> 32kHz External Crystal Oscillator (XOSC32K) Control
@@ -205,7 +205,7 @@
 // <i> Indicates whether External 32K Oscillator is enabled or not
 // <id> xosc32k_arch_enable
 #ifndef CONF_XOSC32K_ENABLE
-#define CONF_XOSC32K_ENABLE 0
+#define CONF_XOSC32K_ENABLE 1
 #endif
 
 // <q> On Demand
@@ -223,7 +223,7 @@
 // <i> If this bit is 1: The oscillator is not stopped in standby sleep mode.
 // <id> xosc32k_arch_runstdby
 #ifndef CONF_XOSC32K_RUNSTDBY
-#define CONF_XOSC32K_RUNSTDBY 0
+#define CONF_XOSC32K_RUNSTDBY 1
 #endif
 
 // <q> Enable 1K
@@ -237,14 +237,14 @@
 // <i> Enable 32 Khz Output
 // <id> xosc32k_arch_en32k
 #ifndef CONF_XOSC32K_EN32K
-#define CONF_XOSC32K_EN32K 0
+#define CONF_XOSC32K_EN32K 1
 #endif
 
 // <q> Enable XTAL
 // <i> Enable XTAL
 // <id> xosc32k_arch_xtalen
 #ifndef CONF_XOSC32K_XTALEN
-#define CONF_XOSC32K_XTALEN 0
+#define CONF_XOSC32K_XTALEN 1
 #endif
 
 // <q> Write Lock
@@ -274,7 +274,7 @@
 // <i> Default: 122 us
 // <id> xosc32k_arch_startup
 #ifndef CONF_XOSC32K_STARTUP
-#define CONF_XOSC32K_STARTUP CONF_XOSC32K_STARTUP_TIME_122MCS
+#define CONF_XOSC32K_STARTUP CONF_XOSC32K_STARTUP_TIME_2000092MCS
 #endif
 
 // </h>
diff --git a/ports/atmel-samd/asf4_conf/samd21/peripheral_clk_config.h b/ports/atmel-samd/asf4_conf/samd21/peripheral_clk_config.h
index cb7dad204..f47277602 100644
--- a/ports/atmel-samd/asf4_conf/samd21/peripheral_clk_config.h
+++ b/ports/atmel-samd/asf4_conf/samd21/peripheral_clk_config.h
@@ -321,7 +321,7 @@
 
 // <i> Select the clock source for RTC.
 #ifndef CONF_GCLK_RTC_SRC
-#define CONF_GCLK_RTC_SRC GCLK_CLKCTRL_GEN_GCLK0_Val
+#define CONF_GCLK_RTC_SRC GCLK_CLKCTRL_GEN_GCLK2_Val
 #endif
 
 /**
diff --git a/ports/atmel-samd/asf4_conf/samd51/hpl_gclk_config.h b/ports/atmel-samd/asf4_conf/samd51/hpl_gclk_config.h
index 77793b69a..3e41d2168 100644
--- a/ports/atmel-samd/asf4_conf/samd51/hpl_gclk_config.h
+++ b/ports/atmel-samd/asf4_conf/samd51/hpl_gclk_config.h
@@ -172,7 +172,7 @@
 // <i> Indicates whether generic clock 2 configuration is enabled or not
 // <id> enable_gclk_gen_2
 #ifndef CONF_GCLK_GENERATOR_2_CONFIG
-#define CONF_GCLK_GENERATOR_2_CONFIG 0
+#define CONF_GCLK_GENERATOR_2_CONFIG 1
 #endif
 
 // <h> Generic Clock Generator Control
@@ -188,7 +188,7 @@
 // <i> This defines the clock source for generic clock generator 2
 // <id> gclk_gen_2_oscillator
 #ifndef CONF_GCLK_GEN_2_SOURCE
-#define CONF_GCLK_GEN_2_SOURCE GCLK_GENCTRL_SRC_XOSC1
+#define CONF_GCLK_GEN_2_SOURCE GCLK_GENCTRL_SRC_XOSC32K
 #endif
 
 // <q> Run in Standby
@@ -230,7 +230,7 @@
 // <i> Indicates whether Generic Clock Generator Enable is enabled or not
 // <id> gclk_arch_gen_2_enable
 #ifndef CONF_GCLK_GEN_2_GENEN
-#define CONF_GCLK_GEN_2_GENEN 0
+#define CONF_GCLK_GEN_2_GENEN 1
 #endif
 // </h>
 
@@ -238,7 +238,7 @@
 //<o> Generic clock generator 2 division <0x0000-0xFFFF>
 // <id> gclk_gen_2_div
 #ifndef CONF_GCLK_GEN_2_DIV
-#define CONF_GCLK_GEN_2_DIV 1
+#define CONF_GCLK_GEN_2_DIV 4
 #endif
 // </h>
 // </e>
diff --git a/ports/atmel-samd/asf4_conf/samd51/hpl_osc32kctrl_config.h b/ports/atmel-samd/asf4_conf/samd51/hpl_osc32kctrl_config.h
index ccb262748..73128077c 100644
--- a/ports/atmel-samd/asf4_conf/samd51/hpl_osc32kctrl_config.h
+++ b/ports/atmel-samd/asf4_conf/samd51/hpl_osc32kctrl_config.h
@@ -23,7 +23,7 @@
 // <q> Use 1 kHz output
 // <id> rtc_1khz_selection
 #ifndef CONF_RTCCTRL_1KHZ
-#define CONF_RTCCTRL_1KHZ 1
+#define CONF_RTCCTRL_1KHZ 0
 #endif
 
 #if CONF_RTCCTRL_SRC == GCLK_GENCTRL_SRC_OSCULP32K
@@ -62,7 +62,7 @@
 // <0x6=>8000092us
 // <id> xosc32k_arch_startup
 #ifndef CONF_XOSC32K_STARTUP
-#define CONF_XOSC32K_STARTUP 0x0
+#define CONF_XOSC32K_STARTUP 0x4
 #endif
 
 // <q> On Demand Control
@@ -76,7 +76,7 @@
 // <i> Indicates whether Run in Standby is enabled or not
 // <id> xosc32k_arch_runstdby
 #ifndef CONF_XOSC32K_RUNSTDBY
-#define CONF_XOSC32K_RUNSTDBY 0
+#define CONF_XOSC32K_RUNSTDBY 1
 #endif
 
 // <q> 1kHz Output Enable
@@ -90,7 +90,7 @@
 // <i> Indicates whether 32kHz Output is enabled or not
 // <id> xosc32k_arch_en32k
 #ifndef CONF_XOSC32K_EN32K
-#define CONF_XOSC32K_EN32K 0
+#define CONF_XOSC32K_EN32K 1
 #endif
 
 // <q> Clock Switch Back
@@ -118,7 +118,7 @@
 // <i> Indicates whether the connections between the I/O pads and the external clock or crystal oscillator is enabled or not
 // <id> xosc32k_arch_xtalen
 #ifndef CONF_XOSC32K_XTALEN
-#define CONF_XOSC32K_XTALEN 0
+#define CONF_XOSC32K_XTALEN 1
 #endif
 
 // <o> Control Gain Mode
@@ -137,7 +137,7 @@
 // <i> Indicates whether configuration for OSCULP32K is enabled or not
 // <id> enable_osculp32k
 #ifndef CONF_OSCULP32K_CONFIG
-#define CONF_OSCULP32K_CONFIG 1
+#define CONF_OSCULP32K_CONFIG 0
 #endif
 
 // <h> 32kHz Ultra Low Power Internal Oscillator Control
diff --git a/ports/atmel-samd/asf4_conf/samd51/hpl_rtc_config.h b/ports/atmel-samd/asf4_conf/samd51/hpl_rtc_config.h
index b99821da5..2b0b6712e 100644
--- a/ports/atmel-samd/asf4_conf/samd51/hpl_rtc_config.h
+++ b/ports/atmel-samd/asf4_conf/samd51/hpl_rtc_config.h
@@ -10,6 +10,14 @@
 #define CONF_RTC_ENABLE 1
 #endif
 
+// <q> Force reset RTC on initialization
+// <i> Force RTC to reset on initialization.
+// <i> Note that the previous power down data in RTC is lost if it's enabled.
+// <id> rtc_arch_init_reset
+#ifndef CONF_RTC_INIT_RESET
+#define CONF_RTC_INIT_RESET 0
+#endif
+
 // <o> Prescaler configuration
 // <0x0=>OFF(Peripheral clock divided by 1)
 // <0x1=>Peripheral clock divided by 1
@@ -26,7 +34,7 @@
 // <i> These bits define the RTC clock relative to the peripheral clock
 // <id> rtc_arch_prescaler
 #ifndef CONF_RTC_PRESCALER
-#define CONF_RTC_PRESCALER 0x0
+#define CONF_RTC_PRESCALER 0xb
 
 #endif
 
diff --git a/ports/atmel-samd/common-hal/rtc/RTC.c b/ports/atmel-samd/common-hal/rtc/RTC.c
new file mode 100644
index 000000000..d63e81305
--- /dev/null
+++ b/ports/atmel-samd/common-hal/rtc/RTC.c
@@ -0,0 +1,98 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Noralf Trønnes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdlib.h>
+
+#include <peripheral_clk_config.h>
+#include <hal_init.h>
+#include <hpl_gclk_base.h>
+#include <hpl_pm_base.h>
+#include <hal_calendar.h>
+
+#include "py/obj.h"
+#include "py/runtime.h"
+#include "lib/timeutils/timeutils.h"
+#include "shared-bindings/rtc/__init__.h"
+
+static struct calendar_descriptor calendar;
+
+void rtc_init(void) {
+#ifdef SAMD21
+    _gclk_enable_channel(RTC_GCLK_ID, CONF_GCLK_RTC_SRC);
+#endif
+#ifdef SAMD51
+    hri_mclk_set_APBAMASK_RTC_bit(MCLK);
+#endif
+    calendar_init(&calendar, RTC);
+    calendar_set_baseyear(&calendar, 2000);
+    calendar_enable(&calendar);
+}
+
+void common_hal_rtc_get_time(timeutils_struct_time_t *tm) {
+    struct calendar_date_time datetime;
+    calendar_get_date_time(&calendar, &datetime);
+
+    tm->tm_year = datetime.date.year;
+    tm->tm_mon  = datetime.date.month;
+    tm->tm_mday = datetime.date.day;
+    tm->tm_hour = datetime.time.hour;
+    tm->tm_min  = datetime.time.min;
+    tm->tm_sec  = datetime.time.sec;
+}
+
+void common_hal_rtc_set_time(timeutils_struct_time_t *tm) {
+    struct calendar_date date = {
+        .year = tm->tm_year,
+        .month = tm->tm_mon,
+        .day = tm->tm_mday,
+    };
+    calendar_set_date(&calendar, &date);
+
+    struct calendar_time time = {
+        .hour = tm->tm_hour,
+        .min = tm->tm_min,
+        .sec = tm->tm_sec,
+    };
+    calendar_set_time(&calendar, &time);
+}
+
+// A positive value speeds up the clock by removing clock cycles.
+int common_hal_rtc_get_calibration(void) {
+    int calibration = hri_rtcmode0_read_FREQCORR_VALUE_bf(calendar.device.hw);
+
+    if (!hri_rtcmode0_get_FREQCORR_SIGN_bit(calendar.device.hw))
+        calibration = -calibration;
+
+    return calibration;
+}
+
+void common_hal_rtc_set_calibration(int calibration) {
+    if (calibration > 127 || calibration < -127)
+        mp_raise_ValueError("calibration value out of range +/-127");
+
+    hri_rtcmode0_write_FREQCORR_SIGN_bit(calendar.device.hw, calibration < 0 ? 0 : 1);
+    hri_rtcmode0_write_FREQCORR_VALUE_bf(calendar.device.hw, abs(calibration));
+}
diff --git a/ports/atmel-samd/common-hal/rtc/RTC.h b/ports/atmel-samd/common-hal/rtc/RTC.h
new file mode 100644
index 000000000..1d63b2dea
--- /dev/null
+++ b/ports/atmel-samd/common-hal/rtc/RTC.h
@@ -0,0 +1,32 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Noralf Trønnes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_RTC_RTC_H
+#define MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_RTC_RTC_H
+
+extern void rtc_init(void);
+
+#endif  // MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_RTC_RTC_H
diff --git a/ports/atmel-samd/common-hal/rtc/__init__.c b/ports/atmel-samd/common-hal/rtc/__init__.c
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/ports/atmel-samd/common-hal/rtc/__init__.c
diff --git a/ports/atmel-samd/mpconfigport.h b/ports/atmel-samd/mpconfigport.h
index 7dbcd5062..5ac06944a 100644
--- a/ports/atmel-samd/mpconfigport.h
+++ b/ports/atmel-samd/mpconfigport.h
@@ -166,6 +166,7 @@ extern const struct _mp_obj_module_t board_module;
 extern const struct _mp_obj_module_t math_module;
 extern const struct _mp_obj_module_t os_module;
 extern const struct _mp_obj_module_t random_module;
+extern const struct _mp_obj_module_t rtc_module;
 extern const struct _mp_obj_module_t storage_module;
 extern const struct _mp_obj_module_t struct_module;
 extern const struct _mp_obj_module_t time_module;
@@ -234,6 +235,7 @@ extern const struct _mp_obj_module_t usb_hid_module;
     { MP_OBJ_NEW_QSTR(MP_QSTR_os), (mp_obj_t)&os_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_pulseio), (mp_obj_t)&pulseio_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_random), (mp_obj_t)&random_module }, \
+    { MP_OBJ_NEW_QSTR(MP_QSTR_rtc), (mp_obj_t)&rtc_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_storage), (mp_obj_t)&storage_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_struct), (mp_obj_t)&struct_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_supervisor), (mp_obj_t)&supervisor_module }, \
@@ -266,6 +268,7 @@ extern const struct _mp_obj_module_t usb_hid_module;
     const char *readline_hist[8]; \
     vstr_t *repl_line; \
     mp_obj_t playing_audio[AUDIO_DMA_CHANNEL_COUNT]; \
+    mp_obj_t rtc_time_source; \
     FLASH_ROOT_POINTERS \
 
 void run_background_tasks(void);
diff --git a/ports/atmel-samd/supervisor/port.c b/ports/atmel-samd/supervisor/port.c
index 963817dbf..3ac9cbfc9 100644
--- a/ports/atmel-samd/supervisor/port.c
+++ b/ports/atmel-samd/supervisor/port.c
@@ -52,7 +52,9 @@
 #include "common-hal/pulseio/PulseIn.h"
 #include "common-hal/pulseio/PulseOut.h"
 #include "common-hal/pulseio/PWMOut.h"
+#include "common-hal/rtc/RTC.h"
 #include "common-hal/usb_hid/Device.h"
+#include "shared-bindings/rtc/__init__.h"
 #include "clocks.h"
 #include "events.h"
 #include "shared_dma.h"
@@ -124,6 +126,7 @@ safe_mode_t port_init(void) {
 
     // Configure millisecond timer initialization.
     tick_init();
+    rtc_init();
 
     // Init the nvm controller.
     // struct nvm_config config_nvm;
@@ -180,6 +183,7 @@ void reset_port(void) {
     pulsein_reset();
     pulseout_reset();
     pwmout_reset();
+    rtc_reset();
 
     reset_gclks();
 
diff --git a/shared-bindings/rtc/RTC.c b/shared-bindings/rtc/RTC.c
new file mode 100644
index 000000000..aeedad12d
--- /dev/null
+++ b/shared-bindings/rtc/RTC.c
@@ -0,0 +1,135 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Noralf Trønnes
+ * Copyright (c) 2013, 2014 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <string.h>
+
+#include "py/obj.h"
+#include "py/objproperty.h"
+#include "py/runtime.h"
+#include "lib/timeutils/timeutils.h"
+#include "shared-bindings/rtc/__init__.h"
+#include "shared-bindings/rtc/RTC.h"
+#include "shared-bindings/time/__init__.h"
+
+void MP_WEAK common_hal_rtc_get_time(timeutils_struct_time_t *tm) {
+    mp_raise_NotImplementedError("RTC is not supported on this board");
+}
+
+void MP_WEAK common_hal_rtc_set_time(timeutils_struct_time_t *tm) {
+    mp_raise_NotImplementedError("RTC is not supported on this board");
+}
+
+int MP_WEAK common_hal_rtc_get_calibration(void) {
+    return 0;
+}
+
+void MP_WEAK common_hal_rtc_set_calibration(int calibration) {
+    mp_raise_NotImplementedError("RTC calibration is not supported on this board");
+}
+
+const rtc_rtc_obj_t rtc_rtc_obj = {{&rtc_rtc_type}};
+
+//| .. currentmodule:: rtc
+//|
+//| :class:`RTC` --- Real Time Clock
+//| --------------------------------
+//|
+//| .. class:: RTC()
+//|
+//|   This class represents the onboard Real Time Clock. It is a singleton and will always return the same instance.
+//|
+STATIC mp_obj_t rtc_rtc_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+    // No arguments
+    mp_arg_check_num(n_args, n_kw, 0, 0, false);
+
+    // return constant object
+    return (mp_obj_t)&rtc_rtc_obj;
+}
+
+//|   .. attribute:: datetime
+//|
+//|       The date and time of the RTC.
+//|
+STATIC mp_obj_t rtc_rtc_obj_get_datetime(mp_obj_t self_in) {
+    timeutils_struct_time_t tm;
+    common_hal_rtc_get_time(&tm);
+    return struct_time_from_tm(&tm);
+}
+MP_DEFINE_CONST_FUN_OBJ_1(rtc_rtc_get_datetime_obj, rtc_rtc_obj_get_datetime);
+
+STATIC mp_obj_t rtc_rtc_obj_set_datetime(mp_obj_t self_in, mp_obj_t datetime) {
+    timeutils_struct_time_t tm;
+    struct_time_to_tm(datetime, &tm);
+    common_hal_rtc_set_time(&tm);
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_2(rtc_rtc_set_datetime_obj, rtc_rtc_obj_set_datetime);
+
+const mp_obj_property_t rtc_rtc_datetime_obj = {
+    .base.type = &mp_type_property,
+    .proxy = {(mp_obj_t)&rtc_rtc_get_datetime_obj,
+              (mp_obj_t)&rtc_rtc_set_datetime_obj,
+              (mp_obj_t)&mp_const_none_obj},
+};
+
+//|   .. attribute:: calibration
+//|
+//|     The RTC calibration value.
+//|     A positive value speeds up the clock and a negative value slows it down.
+//|     Range and value is hardware specific, but one step is often approx. 1 ppm.
+//|
+STATIC mp_obj_t rtc_rtc_obj_get_calibration(mp_obj_t self_in) {
+    int calibration = common_hal_rtc_get_calibration();
+    return mp_obj_new_int(calibration);
+}
+MP_DEFINE_CONST_FUN_OBJ_1(rtc_rtc_get_calibration_obj, rtc_rtc_obj_get_calibration);
+
+STATIC mp_obj_t rtc_rtc_obj_set_calibration(mp_obj_t self_in, mp_obj_t calibration) {
+    common_hal_rtc_set_calibration(mp_obj_get_int(calibration));
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_2(rtc_rtc_set_calibration_obj, rtc_rtc_obj_set_calibration);
+
+const mp_obj_property_t rtc_rtc_calibration_obj = {
+    .base.type = &mp_type_property,
+    .proxy = {(mp_obj_t)&rtc_rtc_get_calibration_obj,
+              (mp_obj_t)&rtc_rtc_set_calibration_obj,
+              (mp_obj_t)&mp_const_none_obj},
+};
+
+STATIC const mp_rom_map_elem_t rtc_rtc_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_datetime), MP_ROM_PTR(&rtc_rtc_datetime_obj) },
+    { MP_ROM_QSTR(MP_QSTR_calibration), MP_ROM_PTR(&rtc_rtc_calibration_obj) },
+};
+STATIC MP_DEFINE_CONST_DICT(rtc_rtc_locals_dict, rtc_rtc_locals_dict_table);
+
+const mp_obj_type_t rtc_rtc_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_RTC,
+    .make_new = rtc_rtc_make_new,
+    .locals_dict = (mp_obj_dict_t*)&rtc_rtc_locals_dict,
+};
diff --git a/shared-bindings/rtc/RTC.h b/shared-bindings/rtc/RTC.h
new file mode 100644
index 000000000..76510bd72
--- /dev/null
+++ b/shared-bindings/rtc/RTC.h
@@ -0,0 +1,49 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Noralf Trønnes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef MICROPY_INCLUDED_SHARED_BINDINGS_RTC_RTC_H
+#define MICROPY_INCLUDED_SHARED_BINDINGS_RTC_RTC_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "lib/timeutils/timeutils.h"
+
+extern void common_hal_rtc_get_time(timeutils_struct_time_t *tm);
+extern void common_hal_rtc_set_time(timeutils_struct_time_t *tm);
+
+extern int common_hal_rtc_get_calibration(void);
+extern void common_hal_rtc_set_calibration(int calibration);
+
+extern const mp_obj_type_t rtc_rtc_type;
+
+typedef struct _rtc_rtc_obj_t {
+    mp_obj_base_t base;
+} rtc_rtc_obj_t;
+
+extern const rtc_rtc_obj_t rtc_rtc_obj;
+
+#endif  // MICROPY_INCLUDED_SHARED_BINDINGS_RTC_RTC_H
diff --git a/shared-bindings/rtc/__init__.c b/shared-bindings/rtc/__init__.c
new file mode 100644
index 000000000..ac67a7131
--- /dev/null
+++ b/shared-bindings/rtc/__init__.c
@@ -0,0 +1,100 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Noralf Trønnes
+ * Copyright (c) 2013, 2014 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/obj.h"
+#include "py/runtime.h"
+#include "shared-bindings/rtc/__init__.h"
+#include "shared-bindings/rtc/RTC.h"
+#include "shared-bindings/time/__init__.h"
+
+//| :mod:`rtc` --- Real Time Clock
+//| ========================================================
+//|
+//| .. module:: rtc
+//|   :synopsis: Real Time Clock
+//|   :platform: SAMD21
+//|
+//| The `rtc` module provides support for a Real Time Clock.
+//| It also backs the `time.time()` and `time.localtime()` functions using the onboard RTC if present.
+//|
+//| Libraries
+//|
+//| .. toctree::
+//|     :maxdepth: 3
+//|
+//|     RTC
+//|
+
+void rtc_reset(void) {
+    MP_STATE_VM(rtc_time_source) = (mp_obj_t)&rtc_rtc_obj;
+}
+
+mp_obj_t rtc_get_time_source_time(void) {
+    mp_obj_t datetime = mp_load_attr(MP_STATE_VM(rtc_time_source), MP_QSTR_datetime);
+    timeutils_struct_time_t tm;
+    struct_time_to_tm(datetime, &tm);
+    // This sets tm_wday and tm_yday
+    return struct_time_from_tm(&tm);
+}
+
+//| .. function:: set_time_source(rtc)
+//|
+//|   Sets the rtc time source used by time.localtime().
+//|   The default is `rtc.RTC()`.
+//|
+//|   Example usage::
+//|
+//|     import rtc
+//|     import time
+//|
+//|     class RTC(object):
+//|         @property
+//|         def datetime(self):
+//|             return time.struct_time((2018, 3, 17, 21, 1, 47, 0, 0, 0))
+//|
+//|     r = RTC()
+//|     rtc.set_time_source(r)
+//|
+STATIC mp_obj_t rtc_set_time_source(mp_obj_t time_source) {
+    MP_STATE_VM(rtc_time_source) = time_source;
+
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_1(rtc_set_time_source_obj, rtc_set_time_source);
+
+STATIC const mp_rom_map_elem_t rtc_module_globals_table[] = {
+    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_rtc) },
+    { MP_ROM_QSTR(MP_QSTR_set_time_source), MP_ROM_PTR(&rtc_set_time_source_obj) },
+    { MP_ROM_QSTR(MP_QSTR_RTC), MP_ROM_PTR(&rtc_rtc_type) },
+};
+
+STATIC MP_DEFINE_CONST_DICT(rtc_module_globals, rtc_module_globals_table);
+
+const mp_obj_module_t rtc_module = {
+    .base = { &mp_type_module },
+    .globals = (mp_obj_dict_t*)&rtc_module_globals,
+};
diff --git a/shared-bindings/rtc/__init__.h b/shared-bindings/rtc/__init__.h
new file mode 100644
index 000000000..0ee51fba5
--- /dev/null
+++ b/shared-bindings/rtc/__init__.h
@@ -0,0 +1,33 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Noralf Trønnes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef MICROPY_INCLUDED_SHARED_BINDINGS_RTC___INIT___H
+#define MICROPY_INCLUDED_SHARED_BINDINGS_RTC___INIT___H
+
+extern void rtc_reset(void);
+extern mp_obj_t rtc_get_time_source_time(void);
+
+#endif  // MICROPY_INCLUDED_SHARED_BINDINGS_RTC___INIT___H
diff --git a/shared-bindings/time/__init__.c b/shared-bindings/time/__init__.c
index 6956cc4e6..b4137706e 100644
--- a/shared-bindings/time/__init__.c
+++ b/shared-bindings/time/__init__.c
@@ -30,6 +30,8 @@
 
 #include "py/obj.h"
 #include "py/objnamedtuple.h"
+#include "lib/timeutils/timeutils.h"
+#include "shared-bindings/rtc/__init__.h"
 #include "shared-bindings/time/__init__.h"
 
 //| :mod:`time` --- time and timing related functions
@@ -133,6 +135,122 @@ const mp_obj_namedtuple_type_t struct_time_type_obj = {
         MP_QSTR_tm_isdst
     },
 };
+
+mp_obj_t struct_time_from_tm(timeutils_struct_time_t *tm) {
+    timeutils_struct_time_t tmp;
+    mp_uint_t secs = timeutils_seconds_since_2000(tm->tm_year, tm->tm_mon, tm->tm_mday,
+                                                  tm->tm_hour, tm->tm_min, tm->tm_sec);
+    timeutils_seconds_since_2000_to_struct_time(secs, &tmp);
+    tm->tm_wday = tmp.tm_wday;
+    tm->tm_yday = tmp.tm_yday;
+
+    mp_obj_t elems[9] = {
+        mp_obj_new_int(tm->tm_year),
+        mp_obj_new_int(tm->tm_mon),
+        mp_obj_new_int(tm->tm_mday),
+        mp_obj_new_int(tm->tm_hour),
+        mp_obj_new_int(tm->tm_min),
+        mp_obj_new_int(tm->tm_sec),
+        mp_obj_new_int(tm->tm_wday),
+        mp_obj_new_int(tm->tm_yday),
+        mp_obj_new_int(-1), // tm_isdst is not supported
+    };
+
+    return namedtuple_make_new((const mp_obj_type_t*)&struct_time_type_obj, 9, 0, elems);
+};
+
+void struct_time_to_tm(mp_obj_t t, timeutils_struct_time_t *tm) {
+    mp_obj_t *elems;
+    size_t len;
+
+    if (!MP_OBJ_IS_TYPE(t, &mp_type_tuple) && !MP_OBJ_IS_TYPE(t, MP_OBJ_FROM_PTR(&struct_time_type_obj))) {
+        mp_raise_TypeError("Tuple or struct_time argument required");
+    }
+
+    mp_obj_tuple_get(t, &len, &elems);
+    if (len != 9) {
+        mp_raise_TypeError("function takes exactly 9 arguments");
+    }
+
+    tm->tm_year = mp_obj_get_int(elems[0]);
+    tm->tm_mon = mp_obj_get_int(elems[1]);
+    tm->tm_mday = mp_obj_get_int(elems[2]);
+    tm->tm_hour = mp_obj_get_int(elems[3]);
+    tm->tm_min = mp_obj_get_int(elems[4]);
+    tm->tm_sec = mp_obj_get_int(elems[5]);
+    tm->tm_wday = mp_obj_get_int(elems[6]);
+    tm->tm_yday = mp_obj_get_int(elems[7]);
+    // elems[8] tm_isdst is not supported
+}
+
+mp_obj_t MP_WEAK rtc_get_time_source_time(void) {
+    mp_raise_RuntimeError("RTC is not supported on this board");
+}
+
+//| .. method:: time()
+//|
+//|   Return the current time in seconds since since Jan 1, 2000.
+//|
+//|   :return: the current time
+//|   :rtype: int
+//|
+STATIC mp_obj_t time_time(void) {
+    timeutils_struct_time_t tm;
+    struct_time_to_tm(rtc_get_time_source_time(), &tm);
+    mp_uint_t secs = timeutils_seconds_since_2000(tm.tm_year, tm.tm_mon, tm.tm_mday, // mp_uint_t date
+                                                  tm.tm_hour, tm.tm_min, tm.tm_sec);
+    return mp_obj_new_int_from_uint(secs);
+}
+MP_DEFINE_CONST_FUN_OBJ_0(time_time_obj, time_time);
+
+//| .. method:: localtime([secs])
+//|
+//|   Convert a time expressed in seconds since Jan 1, 2000 to a struct_time in
+//|   local time. If secs is not provided or None, the current time as returned
+//|   by time() is used.
+//|
+//|   :return: the current time
+//|   :rtype: time.struct_time
+//|
+STATIC mp_obj_t time_localtime(size_t n_args, const mp_obj_t *args) {
+    if (n_args == 0 || args[0] == mp_const_none) {
+        return rtc_get_time_source_time();
+    }
+
+    timeutils_struct_time_t tm;
+    timeutils_seconds_since_2000_to_struct_time(mp_obj_get_int(args[0]), &tm);
+
+    return struct_time_from_tm(&tm);
+}
+MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(time_localtime_obj, 0, 1, time_localtime);
+
+//| .. method:: mktime(t)
+//|
+//|   This is the inverse function of localtime(). Its argument is the
+//|   struct_time or full 9-tuple (since the dst flag is needed; use -1 as the
+//|   dst flag if it is unknown) which expresses the time in local time, not UTC.
+//|   The earliest date for which it can generate a time is Jan 1, 2000.
+//|
+//|   :return: seconds
+//|   :rtype: int
+//|
+STATIC mp_obj_t time_mktime(mp_obj_t t) {
+    mp_obj_t *elem;
+    size_t len;
+
+    if (!MP_OBJ_IS_TYPE(t, &mp_type_tuple) && !MP_OBJ_IS_TYPE(t, MP_OBJ_FROM_PTR(&struct_time_type_obj))) {
+        mp_raise_TypeError("Tuple or struct_time argument required");
+    }
+
+    mp_obj_tuple_get(t, &len, &elem);
+    if (len != 9) {
+        mp_raise_TypeError("function takes exactly 9 arguments");
+    }
+
+    return mp_obj_new_int_from_uint(timeutils_mktime(mp_obj_get_int(elem[0]), mp_obj_get_int(elem[1]), mp_obj_get_int(elem[2]),
+                                                     mp_obj_get_int(elem[3]), mp_obj_get_int(elem[4]), mp_obj_get_int(elem[5])));
+}
+MP_DEFINE_CONST_FUN_OBJ_1(time_mktime_obj, time_mktime);
 #endif
 
 STATIC const mp_rom_map_elem_t time_module_globals_table[] = {
@@ -142,7 +260,10 @@ STATIC const mp_rom_map_elem_t time_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_sleep), MP_ROM_PTR(&time_sleep_obj) },
     #if MICROPY_PY_COLLECTIONS
     { MP_ROM_QSTR(MP_QSTR_struct_time), MP_ROM_PTR(&struct_time_type_obj) },
+    { MP_ROM_QSTR(MP_QSTR_localtime), MP_ROM_PTR(&time_localtime_obj) },
+    { MP_ROM_QSTR(MP_QSTR_mktime), MP_ROM_PTR(&time_mktime_obj) },
     #endif
+    { MP_ROM_QSTR(MP_QSTR_time), MP_ROM_PTR(&time_time_obj) },
 };
 
 STATIC MP_DEFINE_CONST_DICT(time_module_globals, time_module_globals_table);
diff --git a/shared-bindings/time/__init__.h b/shared-bindings/time/__init__.h
index f6ecb5989..c5a0b47fc 100644
--- a/shared-bindings/time/__init__.h
+++ b/shared-bindings/time/__init__.h
@@ -30,6 +30,11 @@
 #include <stdint.h>
 #include <stdbool.h>
 
+#include "lib/timeutils/timeutils.h"
+
+extern mp_obj_t struct_time_from_tm(timeutils_struct_time_t *tm);
+extern void struct_time_to_tm(mp_obj_t t, timeutils_struct_time_t *tm);
+
 extern uint64_t common_hal_time_monotonic(void);
 extern void common_hal_time_delay_ms(uint32_t);