Controlling NJW1194 pre-amp with RasPi Pico or Arduino Nano

NJW1194 has:

• 4 stereo inputs
• SPI interface
• Volume control (separate L/R)
• Tone controls (Bass/Treble)

Requirements:

Audio inputs:

• AM Radio
• FM Radio
• IP Radio (Raspberry Pi as an internet radio stream receiver)
• External input (TV)

MCU inputs - total 12 GPI:

• Power switch - 1 GPI
• Phono/AM/FM switch - 3 GPI
• Tape Select - 1 GPI
• Volume (rotary ctrl) - 2 GPI
• Mute - 1 GPI
• Bass/Treble/Balance - 3 ADC
• IR receiver - 1 GPI

MCU outputs - total 9 GPO:

• Power relay - 1 GPO
• SPI (Data, Clock, ChipSelect) - 3 GPO
• RGB dial light (PWM) - 3 GPO
• Display I2C - 2 GPO

MCU needs 21 GPIO lines in total, plus maybe another 2 to "talk" to Raspberry Pi ...

TODO:

• Utilize rotary encoder w. push button for Volume/Mute control
• Use existing pots fed to ADC for controlling Tone + Balance