esp8266: Implement basic deep-sleep capabilities.

Use the machine.deepsleep() function to enter the sleep mode.  Use the
RTC to configure the alarm to wake the device.

Basic use is the following:

    import machine

    # configure RTC's ALARM0 to wake device from deep sleep
    rtc = machine.RTC()
    rtc.irq(trigger=rtc.ALARM0, wake=machine.DEEPSLEEP)

    # do other things
    # ...

    # set ALARM0's alarm to wake after 10 seconds
    rtc.alarm(rtc.ALARM0, 10000)

    # enter deep-sleep state (system is reset upon waking)
    machine.deepsleep()

To detect if the system woke from a deep sleep use:

    if machine.reset_cause() == machine.DEEPSLEEP_RESET:
        print('woke from deep sleep')

3 files changed, 101 insertions, 0 deletions

diff --git a/esp8266/modmachine.c b/esp8266/modmachine.c
index 83fb8d3504..c75f6e528d 100644
--- a/esp8266/modmachine.c
+++ b/esp8266/modmachine.c
@@ -33,14 +33,20 @@
 #include "extmod/machine_i2c.h"
 #include "utils.h"
 #include "modpyb.h"
+#include "modpybrtc.h"
 
 #include "os_type.h"
 #include "osapi.h"
 #include "etshal.h"
+#include "ets_alt_task.h"
 #include "user_interface.h"
 
 #if MICROPY_PY_MACHINE
 
+//#define MACHINE_WAKE_IDLE (0x01)
+//#define MACHINE_WAKE_SLEEP (0x02)
+#define MACHINE_WAKE_DEEPSLEEP (0x04)
+
 STATIC mp_obj_t machine_freq(mp_uint_t n_args, const mp_obj_t *args) {
     if (n_args == 0) {
         // get
@@ -75,6 +81,40 @@ STATIC mp_obj_t machine_unique_id(void) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_0(machine_unique_id_obj, machine_unique_id);
 
+STATIC mp_obj_t machine_deepsleep(void) {
+    // default to sleep forever
+    uint32_t sleep_us = 0;
+
+    // see if RTC.ALARM0 should wake the device
+    if (pyb_rtc_alarm0_wake & MACHINE_WAKE_DEEPSLEEP) {
+        uint64_t t = pyb_rtc_get_us_since_2000();
+        if (pyb_rtc_alarm0_expiry <= t) {
+            sleep_us = 1; // alarm already expired so wake immediately
+        } else {
+            uint64_t delta = pyb_rtc_alarm0_expiry - t;
+            if (delta <= 0xffffffff) {
+                // sleep for the desired time
+                sleep_us = delta;
+            } else {
+                // overflow, just set to maximum sleep time
+                sleep_us = 0xffffffff;
+            }
+        }
+    }
+
+    // put the device in a deep-sleep state
+    system_deep_sleep_set_option(0); // default power down mode; TODO check this
+    system_deep_sleep(sleep_us);
+
+    for (;;) {
+        // we must not return
+        ets_loop_iter();
+    }
+
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_0(machine_deepsleep_obj, machine_deepsleep);
+
 typedef struct _esp_timer_obj_t {
     mp_obj_base_t base;
     os_timer_t timer;
@@ -160,7 +200,9 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_reset), MP_ROM_PTR(&machine_reset_obj) },
     { MP_ROM_QSTR(MP_QSTR_reset_cause), MP_ROM_PTR(&machine_reset_cause_obj) },
     { MP_ROM_QSTR(MP_QSTR_unique_id), MP_ROM_PTR(&machine_unique_id_obj) },
+    { MP_ROM_QSTR(MP_QSTR_deepsleep), MP_ROM_PTR(&machine_deepsleep_obj) },
 
+    { MP_ROM_QSTR(MP_QSTR_RTC), MP_ROM_PTR(&pyb_rtc_type) },
     { MP_ROM_QSTR(MP_QSTR_Timer), MP_ROM_PTR(&esp_timer_type) },
     { MP_ROM_QSTR(MP_QSTR_Pin), MP_ROM_PTR(&pyb_pin_type) },
     { MP_ROM_QSTR(MP_QSTR_PWM), MP_ROM_PTR(&pyb_pwm_type) },
@@ -168,6 +210,14 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_UART), MP_ROM_PTR(&pyb_uart_type) },
     { MP_ROM_QSTR(MP_QSTR_I2C), MP_ROM_PTR(&machine_i2c_type) },
     { MP_ROM_QSTR(MP_QSTR_SPI), MP_ROM_PTR(&pyb_spi_type) },
+
+    // wake abilities
+    { MP_ROM_QSTR(MP_QSTR_DEEPSLEEP), MP_ROM_INT(MACHINE_WAKE_DEEPSLEEP) },
+
+    // reset causes
+    { MP_ROM_QSTR(MP_QSTR_PWR_ON_RESET), MP_ROM_INT(REASON_EXT_SYS_RST) },
+    { MP_ROM_QSTR(MP_QSTR_HARD_RESET), MP_ROM_INT(REASON_EXT_SYS_RST) },
+    { MP_ROM_QSTR(MP_QSTR_DEEPSLEEP_RESET), MP_ROM_INT(REASON_DEEP_SLEEP_AWAKE) },
 };
 
 STATIC MP_DEFINE_CONST_DICT(machine_module_globals, machine_module_globals_table);
diff --git a/esp8266/modpybrtc.c b/esp8266/modpybrtc.c
index 594c34b157..e62dc88175 100644
--- a/esp8266/modpybrtc.c
+++ b/esp8266/modpybrtc.c
@@ -49,6 +49,10 @@ typedef struct _pyb_rtc_obj_t {
 // singleton RTC object
 STATIC const pyb_rtc_obj_t pyb_rtc_obj = {{&pyb_rtc_type}};
 
+// ALARM0 state
+uint32_t pyb_rtc_alarm0_wake; // see MACHINE_WAKE_xxx constants
+uint64_t pyb_rtc_alarm0_expiry; // in microseconds
+
 void mp_hal_rtc_init(void) {
     uint32_t magic;
 
@@ -61,6 +65,10 @@ void mp_hal_rtc_init(void) {
         system_rtc_mem_write(MEM_CAL_ADDR, &cal, sizeof(cal));
         system_rtc_mem_write(MEM_DELTA_ADDR, &delta, sizeof(delta));
     }
+
+    // reset ALARM0 state
+    pyb_rtc_alarm0_wake = 0;
+    pyb_rtc_alarm0_expiry = 0;
 }
 
 STATIC mp_obj_t pyb_rtc_make_new(const mp_obj_type_t *type, mp_uint_t n_args, mp_uint_t n_kw, const mp_obj_t *args) {
@@ -177,9 +185,49 @@ STATIC mp_obj_t pyb_rtc_memory(mp_uint_t n_args, const mp_obj_t *args) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(pyb_rtc_memory_obj, 1, 2, pyb_rtc_memory);
 
+STATIC mp_obj_t pyb_rtc_alarm(mp_obj_t self_in, mp_obj_t alarm_id, mp_obj_t time_in) {
+    (void)self_in; // unused
+
+    // check we want alarm0
+    if (mp_obj_get_int(alarm_id) != 0) {
+        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "invalid alarm"));
+    }
+
+    // set expiry time (in microseconds)
+    pyb_rtc_alarm0_expiry = pyb_rtc_get_us_since_2000() + mp_obj_get_int(time_in) * 1000;
+
+    return mp_const_none;
+
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_3(pyb_rtc_alarm_obj, pyb_rtc_alarm);
+
+STATIC mp_obj_t pyb_rtc_irq(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    enum { ARG_trigger, ARG_wake };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_trigger, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
+        { MP_QSTR_wake, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
+    };
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    // check we want alarm0
+    if (args[ARG_trigger].u_int != 0) {
+        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "invalid alarm"));
+    }
+
+    // set the wake value
+    pyb_rtc_alarm0_wake = args[ARG_wake].u_int;
+
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_rtc_irq_obj, 1, pyb_rtc_irq);
+
 STATIC const mp_map_elem_t pyb_rtc_locals_dict_table[] = {
     { MP_OBJ_NEW_QSTR(MP_QSTR_datetime), (mp_obj_t)&pyb_rtc_datetime_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_memory), (mp_obj_t)&pyb_rtc_memory_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_alarm), (mp_obj_t)&pyb_rtc_alarm_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_irq), (mp_obj_t)&pyb_rtc_irq_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_ALARM0), MP_OBJ_NEW_SMALL_INT(0) },
 };
 STATIC MP_DEFINE_CONST_DICT(pyb_rtc_locals_dict, pyb_rtc_locals_dict_table);
 
diff --git a/esp8266/modpybrtc.h b/esp8266/modpybrtc.h
index 2a982d38fa..b4ca780712 100644
--- a/esp8266/modpybrtc.h
+++ b/esp8266/modpybrtc.h
@@ -24,6 +24,9 @@
  * THE SOFTWARE.
  */
 
+extern uint32_t pyb_rtc_alarm0_wake;
+extern uint64_t pyb_rtc_alarm0_expiry;
+
 void pyb_rtc_set_us_since_2000(uint64_t nowus);
 
 uint64_t pyb_rtc_get_us_since_2000();