k9: Add support for Senbono K9

The K9 is similar to the PineTime and P8 devices but does not appear
to use the CST[78]16 touch screen controllers. At present the protocol
is not known (readfrom yields all zeros, readfrom_mem provokes an
exception) so we have a hugely limited interface consisting of the side
button and the touchscreen interrupts (in other words we can treat the
touchscreen like a second button).

Works suprisingly well considering...

Signed-off-by: Daniel Thompson <daniel@redfelineninja.org.uk>

1 files changed, 84 insertions, 0 deletions

diff --git a/wasp/drivers/touch.py b/wasp/drivers/touch.py
new file mode 100644
index 0000000..0b08653
--- /dev/null
+++ b/wasp/drivers/touch.py
@@ -0,0 +1,84 @@
+# SPDX-License-Identifier: LGPL-3.0-or-later
+# Copyright (C) 2020 Daniel Thompson
+
+"""Basic touch sensor driver
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+"""
+
+import array
+import time
+from machine import Pin
+from watch import rtc
+
+class TouchButton:
+    """Simple touch controller driver.
+
+    .. automethod:: __init__
+    """
+
+    def __init__(self, intr, rst, schedule=None):
+        """Specify the bus used by the touch controller.
+
+        :param machine.I2C bus: I2C bus for the CST816S.
+        """
+        self.tp_int = intr
+        self.tp_rst = rst
+        self.schedule = schedule
+        self.event = array.array('H', (0, 0, 0))
+
+        self._reset()
+        self.tp_int.irq(trigger=Pin.IRQ_FALLING, handler=self.get_touch_data)
+
+    def _reset(self):
+        self.tp_rst.off()
+        time.sleep_ms(5)
+        self.tp_rst.on()
+        time.sleep_ms(50)
+        self.event[0] = 0
+        self._wake_at = rtc.get_uptime_ms() + 300
+
+    def get_touch_data(self, pin_obj):
+        """Synthesize a right swipe during interrupt.
+        """
+        self.event[0] = 4
+
+        if self.schedule:
+            self.schedule(self)
+
+    def get_event(self):
+        """Receive a touch event.
+
+        Check for a pending touch event and, if an event is pending,
+        prepare it ready to go in the event queue.
+
+        :return: An event record if an event is received, None otherwise.
+        """
+        if rtc.get_uptime_ms() < self._wake_at:
+            self.event[0] = 0
+
+        if self.event[0] == 0:
+            return None
+
+        return self.event
+
+    def reset_touch_data(self):
+        """Reset touch data.
+
+        Reset touch data, call this function after processing an event.
+        """
+        self.event[0] = 0
+
+    def wake(self):
+        """Wake up touch controller chip.
+
+        Just reset the chip in order to wake it up
+        """
+        self._reset()
+
+    def sleep(self):
+        """Put touch controller chip on sleep mode to save power.
+        """
+        self.tp_rst.off()
+
+        # Ensure get_event() cannot return anything
+        self.event[0] = 0