Initial CST816 touch screen driver

Resolves #23

Author: sfe-SparkFro

cv2_drivers/__init__.py

@@ -1,2 +1,3 @@
 from . import displays
-from . import cameras
+from . import cameras
+from . import touch_screens

cv2_drivers/touch_screens/__init__.py

@@ -0,0 +1 @@
+from . import cst816

cv2_drivers/touch_screens/cst816.py

@@ -0,0 +1,104 @@
+from .cv2_touch_screen import CV2_Touch_Screen
+
+# Derived from:
+# https://github.com/fbiego/CST816S
+class CST816(CV2_Touch_Screen):
+    _I2C_ADDRESS = 0x15
+    _CHIP_ID = 0xB6
+    
+    # Registers
+    _REG_GESTURE_ID = 0x01
+    _REG_FINGER_NUM = 0x02
+    _REG_X_POS_H = 0x03
+    _REG_X_POS_L = 0x04
+    _REG_Y_POS_H = 0x05
+    _REG_Y_POS_L = 0x06
+    _REG_BPC0H = 0xB0
+    _REG_BPC0L = 0xB1
+    _REG_BPC1H = 0xB2
+    _REG_BPC1L = 0xB3
+    _REG_CHIP_ID = 0xA7
+    _REG_PROJ_ID = 0xA8
+    _REG_FW_VERSION = 0xA9
+    _REG_MOTION_MASK = 0xEC
+    _REG_IRQ_PULSE_WIDTH = 0xED
+    _REG_NOR_SCAN_PER = 0xEE
+    _REG_MOTION_SL_ANGLE = 0xEF
+    _REG_LP_SCAN_RAW_1H = 0xF0
+    _REG_LP_SCAN_RAW_1L = 0xF1
+    _REG_LP_SCAN_RAW_2H = 0xF2
+    _REG_LP_SCAN_RAW_2L = 0xF3
+    _REG_LP_AUTO_WAKE_TIME = 0xF4
+    _REG_LP_SCAN_TH = 0xF5
+    _REG_LP_SCAN_WIN = 0xF6
+    _REG_LP_SCAN_FREQ = 0xF7
+    _REG_LP_SCAN_IDAC = 0xF8
+    _REG_AUTO_SLEEP_TIME = 0xF9
+    _REG_IRQ_CTL = 0xFA
+    _REG_AUTO_RESET = 0xFB
+    _REG_LONG_PRESS_TIME = 0xFC
+    _REG_IO_CTL = 0xFD
+    _REG_DIS_AUTO_SLEEP = 0xFE
+
+    def __init__(self, i2c, address=_I2C_ADDRESS, width=240, height=320, rotation=1):
+        self.i2c = i2c
+        self.address = address
+        self.width = width
+        self.height = height
+        self.rotation = rotation
+
+    def is_connected(self):
+        """
+        Check if the CST816 touch screen is connected by reading the chip ID.
+
+        Returns:
+            bool: True if connected, False otherwise
+        """
+        try:
+            # Try to read the chip ID
+            # If it throws an I/O error - the device isn't connected
+            chip_id = self.read_register_value(self._REG_CHIP_ID)
+
+            # Confirm the chip ID is correct
+            if chip_id == self._CHIP_ID:
+                return True
+            else:
+                return False
+        except:
+            return False
+
+    def getChipID(self):
+        return self.read_register_value(self._REG_CHIP_ID)
+
+    def get_touch(self):
+        x = self.read_register_value(self._REG_X_POS_H, 2) & 0x0FFF
+        y = self.read_register_value(self._REG_Y_POS_H, 2) & 0x0FFF
+        touch_num = self.read_register_value(self._REG_FINGER_NUM)
+
+        # Adjust for the rotation
+        if self.rotation == 0:
+            x,y = x, y
+        elif self.rotation == 1:
+            x,y = y, self.width - x
+        elif self.rotation == 2:
+            x,y = self.height - x, self.width - y
+        elif self.rotation == 3:
+            x,y = self.height - y, x
+
+        return (x, y, touch_num)
+
+    def read_register_value(self, reg, num_bytes=1):
+        """
+        Read a single byte from the specified register.
+
+        Args:
+            reg (int): Register address to read from
+
+        Returns:
+            int: Value read from the register
+        """
+        data = self.i2c.readfrom_mem(self.address, reg, num_bytes)
+        value = 0
+        for i in range(num_bytes):
+            value = (value << 8) | data[i]
+        return value

cv2_drivers/touch_screens/cv2_touch_screen.py

@@ -0,0 +1,5 @@
+class CV2_Touch_Screen():
+    def __init__(self):
+        pass
+
+    # TODO: Implement common methods for all touch screens