PWM VU Meter
PWM (Pulse Width Modulation) output allows to show volume signal in such devices as LEDs and gas tubes. The PWM duty cycle changing from 0 to 100 reflects the volume level.
When LEDs are in use the brightness of the LED indicates the volume level in the channel.
The following image shows example of the VU Meter based on gas tubes Nixie IN-9:
Here is the schematic for the tube VU Meter. It's based on the design by Tobias (nixiepeppyATgmail.com). The schematic assumes that the Raspberry Pi should be powered from the GPIO connector. In this case there is no need to connect USB power supply.
Here are the default values for the configuration parameters of the PWM VU Meter defined in config.txt:
[pwm.interface] frequency = 500 gpio.pin.left = 24 gpio.pin.right = 25 update.period = 0.1
- frequency - PWM frequency in Hz.
- gpio.pin.left - GPIO pin number for the left channel (PWM output).
- gpio.pin.right - GPIO pin number for the right channel (PWM output).
- update.period - defines in seconds how often PeppyMeter will send signal to PWM VU Meter.