I'm using an MCP23017 expander to get some extra pins on my Raspberry Pi. It is powered by an external 5v power supply. I have a Piezo buzzer and a simple red led connected. When I turn on the circuit, the LED lights up fine, but the buzzer is very low. I understand this is something to do with frequency, but I'm pretty much a noob to electronics. I tested the buzzer previously to make sure it worked by connecting directly to the RPi and using software PWM with RPi.GPIO.
I really just need a more audible buzzer, not tunes or anything like that. Is this possible with the MCP23017?
I'm using the Python smbus module to write to the pins.