Merge pull request #11 from colinpate/colin_fix_channel

Add support for channels 2 and 3 to control GPIO_18 and GPIO_19 on the Pi 5

Author: CamDavidsonPilon

README.md

@@ -8,6 +8,8 @@ Access the hardware PWM of a Raspberry Pi with Python. More lightweight than alt
 
 1. On the Raspberry Pi, add `dtoverlay=pwm-2chan` to `/boot/config.txt`. This defaults to `GPIO_18` as the pin for `PWM0` and `GPIO_19` as the pin for `PWM1`.
     - Alternatively, you can change `GPIO_18` to `GPIO_12` and `GPIO_19` to `GPIO_13` using `dtoverlay=pwm-2chan,pin=12,func=4,pin2=13,func2=4`.
+    - On the Pi 5, use channels 0 and 1 to control GPIO_12 and GPIO13, respectively; use channels 2 and 3 to control GPIO_18 and GPIO_19, respectively
+    - On all other models, use channels 0 and 1 to control GPIO-18 and GPIO_19, respectively
 2. **Reboot your Raspberry Pi**.
     - You can check everything is working on running `lsmod | grep pwm` and looking for `pwm_bcm2835`
 3. Install this library: `sudo pip3 install rpi-hardware-pwm`

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