Source code for adafruit_focaltouch

# SPDX-FileCopyrightText: 2017 ladyada for Adafruit Industries
#
# SPDX-License-Identifier: MIT

"""
`adafruit_focaltouch`
====================================================

CircuitPython driver for common low-cost FocalTech capacitive touch chips.
Currently supports FT6206 & FT6236.

* Author(s): ladyada

Implementation Notes
--------------------

**Hardware:**

* Adafruit `2.8" TFT LCD with Cap Touch Breakout Board w/MicroSD Socket
  <http://www.adafruit.com/product/2090>`_ (Product ID: 2090)

* Adafruit `2.8" TFT Touch Shield for Arduino w/Capacitive Touch
  <http://www.adafruit.com/product/1947>`_ (Product ID: 1947)

**Software and Dependencies:**

* Adafruit CircuitPython firmware for the ESP8622 and M0-based boards:
  https://github.com/adafruit/circuitpython/releases
* Adafruit's Bus Device library (when using I2C/SPI):
  https://github.com/adafruit/Adafruit_CircuitPython_BusDevice
"""

# imports

__version__ = "0.0.0-auto.0"
__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_FocalTouch.git"

try:
    import struct
except ImportError:
    import ustruct as struct

from adafruit_bus_device.i2c_device import I2CDevice

from micropython import const


_FT6206_DEFAULT_I2C_ADDR = 0x38

_FT6XXX_REG_DATA = const(0x00)
_FT6XXX_REG_NUMTOUCHES = const(0x02)
_FT6XXX_REG_THRESHHOLD = const(0x80)
_FT6XXX_REG_POINTRATE = const(0x88)
_FT6XXX_REG_LIBH = const(0xA1)
_FT6XXX_REG_LIBL = const(0xA2)
_FT6XXX_REG_CHIPID = const(0xA3)
_FT6XXX_REG_FIRMVERS = const(0xA6)
_FT6XXX_REG_VENDID = const(0xA8)
_FT6XXX_REG_RELEASE = const(0xAF)


[docs]class Adafruit_FocalTouch: """ A driver for the FocalTech capacitive touch sensor. """ _debug = False chip = None def __init__( self, i2c, address=_FT6206_DEFAULT_I2C_ADDR, debug=False, irq_pin=None ): self._i2c = I2CDevice(i2c, address) self._debug = debug self._irq_pin = irq_pin chip_data = self._read(_FT6XXX_REG_LIBH, 8) # don't wait for IRQ lib_ver, chip_id, _, _, firm_id, _, vend_id = struct.unpack( ">HBBBBBB", chip_data ) if vend_id != 0x11: raise RuntimeError("Did not find FT chip") if chip_id == 0x06: self.chip = "FT6206" elif chip_id == 0x64: self.chip = "FT6236" if debug: print("Library vers %04X" % lib_ver) print("Firmware ID %02X" % firm_id) print("Point rate %d Hz" % self._read(_FT6XXX_REG_POINTRATE, 1)[0]) print("Thresh %d" % self._read(_FT6XXX_REG_THRESHHOLD, 1)[0]) @property def touched(self): """ Returns the number of touches currently detected """ return self._read(_FT6XXX_REG_NUMTOUCHES, 1, irq_pin=self._irq_pin)[0] # pylint: disable=unused-variable @property def touches(self): """ Returns a list of touchpoint dicts, with 'x' and 'y' containing the touch coordinates, and 'id' as the touch # for multitouch tracking """ touchpoints = [] data = self._read(_FT6XXX_REG_DATA, 32, irq_pin=self._irq_pin) for i in range(2): point_data = data[i * 6 + 3 : i * 6 + 9] if all(i == 255 for i in point_data): continue # print([hex(i) for i in point_data]) x, y, weight, misc = struct.unpack(">HHBB", point_data) # print(x, y, weight, misc) touch_id = y >> 12 x &= 0xFFF y &= 0xFFF point = {"x": x, "y": y, "id": touch_id} touchpoints.append(point) return touchpoints # pylint: enable=unused-variable def _read(self, register, length, irq_pin=None): """Returns an array of 'length' bytes from the 'register'""" with self._i2c as i2c: if irq_pin is not None: while irq_pin.value: pass i2c.write(bytes([register & 0xFF])) result = bytearray(length) i2c.readinto(result) if self._debug: print("\t$%02X => %s" % (register, [hex(i) for i in result])) return result def _write(self, register, values): """Writes an array of 'length' bytes to the 'register'""" with self._i2c as i2c: values = [(v & 0xFF) for v in [register] + values] i2c.write(bytes(values)) if self._debug: print("\t$%02X <= %s" % (values[0], [hex(i) for i in values[1:]]))