68 lines
1.7 KiB
Python
68 lines
1.7 KiB
Python
# SPDX-License-Identifier: LGPL-3.0-or-later
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# Copyright (C) 2020 Daniel Thompson
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"""Hynitron CST816S touch contoller driver
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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"""
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import array
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class CST816S:
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"""Hynitron CST816S I2C touch controller driver.
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.. automethod:: __init__
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"""
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def __init__(self, bus):
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"""Specify the bus used by the touch controller.
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:param machine.I2C bus: I2C bus for the CST816S.
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"""
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self.i2c = bus
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self.dbuf = bytearray(6)
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self.event = array.array('H', (0, 0, 0))
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def get_event(self):
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"""Receive a touch event.
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Check for a pending touch event and, if an event is pending,
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prepare it ready to go in the event queue.
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:return: An event record if an event is received, None otherwise.
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"""
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dbuf = self.dbuf
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event = self.event
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# TODO: check the interrupt pin
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try:
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self.i2c.readfrom_mem_into(21, 1, dbuf)
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except OSError:
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return None
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# Skip junk events
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if dbuf[0] == 0:
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return None
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x = ((dbuf[2] & 0xf) << 8) + dbuf[3]
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y = ((dbuf[4] & 0xf) << 8) + dbuf[5]
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swipe_start = dbuf[2] & 0x80
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# Skip identical events... when the I2C interface comes alive
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# we can still get back stale events
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if dbuf[0] == event[0] and x == event[1] and y == event[2] \
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and not swipe_start:
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return None
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# This is a good event, lets save it
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event[0] = dbuf[0]
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event[1] = x
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event[2] = y
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# Do not forward swipe start events
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if dbuf[2] & 0x80:
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event[0] = 0
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return None
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return event
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