epaper2in13v2: implement deep sleep

This commits defines sleep and wakeup methods to enter deep sleep
and wake from sleep mode. Only the feature has been tested, meaning,
calling sleep and wakeup in SLEEP_MODE_1.

During SLEEP_MODE1, RAM is still accessible and thus it is possible to
write new data but they won't show.
After wakeup, updating display will show the operations done during sleep
mode.

Signed-off-by: Pierre-Yves Kerbrat <pykerbrat@gmail.com>

epaper2in13v2.py

@@ -285,14 +285,22 @@ class EPD:
                 self.send_data(bytearray([color]))
         self.update_display()
 
-    def sleep(self, mode):
+    def set_sleep_mode(self, mode):
+        self.sleep_mode = mode
+
+    def sleep(self):
+        print("Going into sleep %d" % self.sleep_mode)
         self.wait_display()
         self.send_command(DISPLAY_UPDATE_CONTROL_2, b'\xc3') #POWER OFF
         self.send_command(MASTER_ACTIVATION)
 
-        self.send_command(DEEP_SLEEP_MODE, bytearray([mode])) #enter deep sleep
+        self.send_command(DEEP_SLEEP_MODE, bytearray([self.sleep_mode]))
         sleep_ms(100)
+        self.rst(0)
 
+    def wakeup(self):
+        print("wakeup")
+        self.init()
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