add a new deep sleep mode alongside backup mode

1 files changed, 50 insertions, 15 deletions

diff --git a/watch-library/watch/watch_deepsleep.h b/watch-library/watch/watch_deepsleep.h
index 14fe8115..3dadd663 100644
--- a/watch-library/watch/watch_deepsleep.h
+++ b/watch-library/watch/watch_deepsleep.h
@@ -33,7 +33,9 @@
   *        from deep sleep (aka BACKUP) mode.
   * @param pin Either pin BTN_ALARM, A2, or A4. These are the three external wake pins. If the pin
   *            is BTN_ALARM, this function also enables an internal pull down on that pin.
-  * @param callback The callback to be called if this pin triggers outside of deep sleep mode.
+  * @param callback The callback to be called if this pin triggers outside of deep sleep mode. If
+  *                 this is NULL, no callback will be called even in normal mode, but the interrupt
+  *                 will still be enabled so that it can wake from deep sleep or backup mode.
   * @param level The level you wish to scan for: true for rising, false for falling. Note that you
   *              cannot scan for both rising and falling edges like you can with the external interrupt
   *              pins; with the external wake interrupt, you can only get one or the other.
@@ -43,40 +45,73 @@
   *       WILL NOT be called, as the device is basically waking from reset at that point.
   * @warning As of the current SAM L22 silicon revision (rev B), the BTN_ALARM pin cannot wake the
   *          device from BACKUP mode. You can still use this function to register a BTN_ALARM interrupt
-  *          in normal or STANDBY mode, but to wake from BACKUP, you will need to use pin A2 or A4.
+  *          in normal or deep sleep mode, but to wake from BACKUP, you will need to use pin A2 or A4.
   */
 void watch_register_extwake_callback(uint8_t pin, ext_irq_cb_t callback, bool level);
 
-/** @brief Stores data in one of the RTC's backup registers, which retain their data in deep sleep.
+/** @brief Unregisters the interrupt on one of the EXTWAKE pins. This will prevent a value change on
+  *        one of these pins from waking the device from deep sleep or BACKUP modes.
+  * @param pin Either pin BTN_ALARM, A2, or A4. If the pin is BTN_ALARM, this function DOES NOT disable
+  *            the internal pull down on that pin.
+  */
+void watch_disable_extwake_interrupt(uint8_t pin, ext_irq_cb_t callback, bool level);
+
+/** @brief Stores data in one of the RTC's backup registers, which retain their data in the deep sleep
+           and backup modes.
   * @param data An unsigned 32 bit integer with the data you wish to store.
   * @param reg A register from 0-7.
   */
 void watch_store_backup_data(uint32_t data, uint8_t reg);
 
-/** @brief Gets 32 bits of data from the RTC's backup register, which retains its data in deep sleep.
+/** @brief Gets 32 bits of data from the RTC's backup register.
   * @param reg A register from 0-7.
   * @return An unsigned 32 bit integer with the from the backup register.
   */
 uint32_t watch_get_backup_data(uint8_t reg);
 
+/** @brief Enters a deep sleep mode by disabling RAM retention and all peripherals except the RTC and
+  *        (optionally) the LCD. You can wake from this mode by pressing the ALARM button.
+  * @param message Either NULL, or a string representing a message to display while in deep sleep mode. The
+  *                message will be displayed at position 0, so you should pad out the beginning of the string
+  *                with spaces if you wish for the message to appear on line 2, i.e. "    SLEEP". If this
+  *                parameter is NULL, the screen will be blanked, and this function will disable the SLCD
+  *                peripheral for additional power savings. (also note that while the message will replace any
+  *                text on the display, this function will not clear any indicators you have set. This is by
+  *                design, in case you wish to leave an indicator lit in sleep mode.)
+  * @details This deep sleep mode is not the lowest power mode available (see watch_enter_backup_mode), but
+  *          it has the benefit of being able to wake with a press of the ALARM button, and provides an option
+  *          for displaying a message to the user when asleep. The only way to wake from this mode is by
+  *          pressing the ALARM button, or receiving an interrupt on pin A2 or A4 of the nine-pin connector.
+  *          (An alarm interrupt would also work, but this has not yet been implemented.) This function enables
+  *          the ALARM button interrupt for you, but if you wish to wake from the A2 or A4 RTC interrupt, you
+  *          must configure them by calling watch_register_extwake_callback. Note however that your callback
+  *          will not be called in this case.
+  *          Power consumption in deep sleep mode varies a bit with the battery voltage and the temperature,
+  *          but at 3 V and ~25° C you can eoughly estimate:
+  *           * ~12µA current draw with the LCD controller on (message != NULL)
+  *           * ~6.5µA current draw with the LCD controller off (message == NULL)
+  * @note With RAM powered off, your application state will be cleared as soon as you call this function, and
+  *       when the user wakes up the watch, your app will effectively be waking from reset. Your app's @ref
+  *       app_wake_from_deep_sleep function will be called to give your app a chance to restore any state that
+  *       you stored using @ref watch_store_backup_data.
+  */
+void watch_enter_deep_sleep(char *message);
+
 /** @brief Enters the SAM L22's lowest-power mode, BACKUP.
   * @details This function does some housekeeping before entering BACKUP mode. It first disables all
-  *          peripherals except for the RTC, and disables the tick interrupt (since that would wake)
-  *          us up from deep sleep. It also sets an external wake source on the ALARM button, if one
+  *          peripherals except for the RTC, and disables the tick interrupt (since that would wake
+  *          us up from deep sleep). It also sets an external wake source on the ALARM button, if one
   *          was not already set. If you wish to wake from another source, such as one of the external
   *          wake interrupt pins on the 9-pin connector, set that up prior to calling this function.
   * @note If you have a callback set for an external wake interrupt, it will be called if triggered while
   *       in ACTIVE, IDLE or STANDBY modes, but it *will not be called* when waking from BACKUP.
   *       Waking from backup is effectively like waking from reset, except that your @ref
   *       app_wake_from_deep_sleep function will be called.
-  * @warning In initial testing, it seems like the ALARM_BTN pin (PA02 RTC/IN2) cannot wake the device
-  *          from deep sleep mode. There is an errata note (Reference: 15010, linked) that says that
-  *          due to a silicon bug, PB01 cannot be used as RTC/IN2. It seems though that this bug may
-  *          also affect PA02. As a result — and I'm very bummed about this — you cannot use deep sleep
-  *          mode unless you set up an external wake interrupt using a device on the nine-pin connector
-  *          (i.e. an accelerometer with an interrupt pin). Otherwise your only option for waking will
-  *          be to unscrew the watch case and press the reset button on the back of the board.
-  *          http://ww1.microchip.com/downloads/en/DeviceDoc/SAM_L22_Family_Errata_DS80000782B.pdf
+  * @warning On current revisions of the SAM L22 silicon, the ALARM_BTN pin (PA02 RTC/IN2) cannot wake
+  *          the device from deep sleep mode. There is an errata note (Reference: 15010) that says that
+  *          due to a silicon bug, RTC/IN2 is not functional in BACKUP. As a result, you should not call
+  *          this function unless you have a device on the nine-pin connector with an external interrupt
+  *          on pin A2 or A4 (i.e. an accelerometer with an interrupt pin).
   */
-void watch_enter_deep_sleep();
+void watch_enter_backup_mode();
 /// @}