Add Example 3 - Camera

Update HM01B0 with methods `open()`, `read()`, and `release()`
Add HM01B0 camera setup to example boot.py

Author: sfe-SparkFro

drivers/camera/hm01b0_pio.py

@@ -2,7 +2,7 @@
 from machine import Pin, I2C
 from ulab import numpy as np
 from time import sleep_us
-import time
+import cv2
 
 # Derived from:
 # https://github.com/openmv/openmv/blob/5acf5baf92b4314a549bdd068138e5df6cc0bac7/drivers/sensors/hm01b0.c
@@ -289,10 +289,35 @@ def start_pio_dma(self):
             ctrl = dma_ctrl
         )
 
-        Pin(self.pin_vsync).irq(
-            trigger = Pin.IRQ_FALLING,
-            handler = lambda pin: self._vsync_handler()
-        )
+    def active(self, active = None):
+        if active == None:
+            return self.sm.active()
+        
+        self.sm.active(active)
+
+        if active:
+            Pin(self.pin_vsync).irq(
+                trigger = Pin.IRQ_FALLING,
+                handler = lambda pin: self._vsync_handler()
+            )
+        else:
+            Pin(self.pin_vsync).irq(
+                handler = None
+            )
+
+    def open(self):
+        self.active(True)
+
+    def release(self):
+        self.active(False)
+
+    def read(self):
+        """
+        Reads a frame from the camera.
+        Returns:
+            tuple: (success, frame)
+        """
+        return (True, cv2.cvtColor(self.buffer, cv2.COLOR_BayerRG2BGR))
 
     def _vsync_handler(self):
         # Disable DMA before reconfiguring it

examples/boot.py

@@ -5,6 +5,10 @@
 # this based on your specific board and configuration
 spi = machine.SPI(0)
 
+# Initialize I2C bus, assuming default pins on bus 0. You may need to adjust
+# this based on your specific board and configuration
+i2c = machine.I2C(0)
+
 # Initialize display, if available
 try:
     # Import a display driver module. This example assumes the ST7789, which is
@@ -64,3 +68,22 @@
     # Clear the display, if the driver supports it
     if hasattr(display, 'clear'):
         display.clear()
+
+# Initialize camera, if available
+try:
+    # Import a camera driver module. This example assumes the HM01B0, which is
+    # a popular camera module for embedded systems. This example uses a PIO
+    # driver, which is a peripheral interface only available on Raspberry Pi RP2
+    # processors
+    import hm01b0_pio
+
+    # Create a camera object. This will depend on the camera driver you are
+    # using, and you may need to adjust the parameters based on your specific
+    # camera and board configuration
+    camera = hm01b0_pio.HM01B0_PIO(i2c,
+                                   pin_d0=12,
+                                   pin_vsync=13,
+                                   pin_hsync=14,
+                                   pin_pclk=15)
+except ImportError:
+    print("boot.py - Camera driver module not found, skipping camera initialization.")

examples/ex03_camera.py

@@ -0,0 +1,39 @@
+# Import OpenCV
+import cv2
+
+# Open a camera, similar to any other Python environment! In standard OpenCV,
+# you would use `cv2.VideoCapture(0)` or similar, and OpenCV would leverage the
+# host operating system to open a camera object and return it as a
+# `cv2.VideoCapture` object. However, we don't have that luxury in MicroPython,
+# so a camera driver is required instead. Any camera driver can be used, as long
+# as it implements the same methods as the standard OpenCV `cv2.VideoCapture`
+# class, such as `open()`, `read()`, and `release()`
+# 
+# This example assumes a camera driver called `camera` has been initialized by a
+# `boot.py` script. See the example `boot.py` script for more details
+camera.open()
+
+# Loop to continuously read frames from the camera and display them
+while True:
+    # Read a frame from the camera, just like any other Python environment! It
+    # returns a tuple, where the first element is a boolean indicating success,
+    # and the second element is the frame (NumPy array) read from the camera
+    success, frame = camera.read()
+
+    # Check if the frame was read successfully
+    if success == False:
+        print("Error reading frame from camera")
+        break
+
+    # Display the frame
+    cv2.imshow(display, frame)
+
+    # Check for key presses
+    key = cv2.waitKey(1)
+
+    # If the 'q' key is pressed, exit the loop
+    if key == ord('q'):
+        break
+
+# Release the camera, just like in any other Python environment!
+camera.release()