The first 22 pins of the RPI are used for the 18-bit DPI interface of the screen (6 per color plus 4 for clock, signal and position).
4 are defined for the I2S interface for sound (I only need 3)
12 are used for controls (4 direction buttons, 4 action buttons, 2 triggers and start/select)
2 will be used for power management
Beyond the created dt-blob.bin file, I call in my config.txt file different overlays to complete my config :
- i2s-gpio28-31 and hifiberry-dac: to send the sound in PCM format to the DAC.
- gpio-shutdown: so the raspberry can warn that it's done shutting down.
- gpio-poweroff: to order the raspberry to shut down...
- gamepad: this one is an overlay I created so that the use of the GPIOs dedicated to the controls simulate the keys of a keyboard.