Getting speaker to work with STM32F3discovery

[bibble235]

Hi,

Following the code from https://github.com/antoinevg/stm32f3-rust-examples

And my speaker is not making any noise when GND and PA04 connected. 

I have one of these https://www.jaycar.co.nz/27mm-all-purpose-replacement-speaker/p/AS3002

Specifications:

• Type: Mylar Cone
• Output Power: 0.25WRMS
• Impedance: 8Ω
• Dimensions: 27(Dia) x 8(H)mm

Thanks