Update __init__.py to support channels 2, 3 for pi 5

Author: colinpate

rpi_hardware_pwm/__init__.py

@@ -28,6 +28,7 @@ class HardwarePWM:
     Notes
     --------
      - For Rpi 1,2,3,4, use chip=0; For Rpi 5, use chip=2
+     - For Rpi 1,2,3,4 only channels 0 and 1 are available
      - If you get "write error: Invalid argument" - you have to set duty_cycle to 0 before changing period
      - /sys/ pwm interface described here: https://jumpnowtek.com/rpi/Using-the-Raspberry-Pi-Hardware-PWM-timers.html
 
@@ -38,8 +39,8 @@ class HardwarePWM:
 
     def __init__(self, pwm_channel: int, hz: float, chip: int = 0) -> None:
 
-        if pwm_channel not in {0, 1}:
-            raise HardwarePWMException("Only channel 0 and 1 are available on the Rpi.")
+        if pwm_channel not in {0, 1, 2, 3}:
+            raise HardwarePWMException("Only channel 0 and 1 and 2 and 3 are available on the Rpi.")
 
         self.chippath: str = f"/sys/class/pwm/pwmchip{chip}"
         self.pwm_channel = pwm_channel