wasp-os/wasp/drivers/cst816s.py
Daniel Thompson ae5743529f wasp: Switch to scheduling from interrupt
This has two useful properties. Firstly it means the watch will be
maintained in the background, allowing the REPL to be used for
notifications and other updates. Secondly it will save a little bit
of power by reducing the work needed to handle spurious wake ups.

Signed-off-by: Daniel Thompson <daniel@redfelineninja.org.uk>
2020-06-30 23:04:01 +01:00

97 lines
2.5 KiB
Python

# SPDX-License-Identifier: LGPL-3.0-or-later
# Copyright (C) 2020 Daniel Thompson
"""Hynitron CST816S touch contoller driver
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"""
import array
import time
from machine import Pin
class CST816S:
"""Hynitron CST816S I2C touch controller driver.
.. automethod:: __init__
"""
def __init__(self, bus, intr, rst, schedule=None):
"""Specify the bus used by the touch controller.
:param machine.I2C bus: I2C bus for the CST816S.
"""
self.i2c = bus
self.tp_int = intr
self.tp_rst = rst
self.schedule = schedule
self.dbuf = bytearray(6)
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)
def get_touch_data(self, pin_obj):
"""Receive a touch event by interrupt.
Check for a pending touch event and, if an event is pending,
prepare it ready to go in the event queue.
"""
dbuf = self.dbuf
event = self.event
try:
self.i2c.readfrom_mem_into(21, 1, dbuf)
except OSError:
return None
event[0] = dbuf[0] # event
event[1] = ((dbuf[2] & 0xf) << 8) + dbuf[3] # x coord
event[2] = ((dbuf[4] & 0xf) << 8) + dbuf[5] # y coord
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 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.
"""
# Before we can sent the sleep command we have to reset the
# panel to get the I2C hardware running again...
self._reset()
self.i2c.writeto_mem(21, 0xa5, b'\x03')
# Ensure get_event() cannot return anything
self.event[0] = 0