|12 | PWM AUDIO | PWM0 | | OUT | | on Raspberry Pi Zero|
|13 | PWM AUDIO | PWM1 | | OUT | | on Raspberry Pi Zero|
|07 | SPI | | /CE1 | | OUT | | reserved|
|08 | SPI | | /CE0 | | OUT | | reserved|
|09 | SPI | | MISO | | IN | | reserved|
|10 | SPI | | MOSI | | OUT | | reserved|
|11 | SPI | | SCLK | | OUT | | reserved|
|04 | NONE | | | | | | can generate clock signal|
|20 | NONE | | | | | | may be used for DAC DIN|
## Building locally
E.g., to build for Raspberry Pi 4 on a Ubuntu 20.04 build system, you can use the following example. See [`build.yml`](../../tree/main/.github/workflows/build.yml) for complete build steps that create versions for Raspberry Pi 1, 2, 3,and 4 in 32-bit and 64-bit as required.