# MUX - Raspberry Pi Edition This folder contains the necessary sources and information to build a MUX for Raspberry Pis. This mux can be used independently or with the controller. Note : The mux needs to be configured via sources if not used with the controller. ## Important Considerations - The Raspberry Pi 4 has 5 available UARTS and we only document how to wire for UART0/1 and UART5 - The Raspberry Pi's prior to the 4 had only UART0 exposed. Please use ONLY the UART0 configuration and setup for these devices. ## Hardware / BoM | Item | Quantity | Unit Cost | | ---- | -------- | --------- | | [Feather M0 Basic Proto](https://www.adafruit.com/product/2772) | 1 | $19.95 | | [FeatherWing Proto](https://www.adafruit.com/product/2884) | 1 | $4.95 | | [2x20 pin IDC Box Header](https://www.adafruit.com/product/1993) | 1 | $0.75 | | [GPIO Ribbon Cable for Raspberry Pi](https://www.adafruit.com/product/1988) | 1 | $2.95 | | [Header Kit for Feather](https://www.adafruit.com/product/2886) | 1 | $0.96 | | [I2C Non-Volatile FRAM Breakout](https://www.adafruit.com/product/1895) | 2 | $9.95 | ## Schematic This build is ```i2c``` focused for additional parts. Please hookup using standard ```i2c``` methods. | Raspberry Pi Header Pin | Arduino Pin | | ----------------------- | ----------- | | 39 | Gnd | | 8 (TX) | D11 (RX) | | 10 (RX) | D10 (TX) | | 32 (TX) | MISO (RX) | | 33 (RX) | MOSI (TX) | | 1 | NOT CONNECTED TO ANYTHING / CUT PIN ON HEADER | | 2 | NOT CONNECTED TO ANYTHING / CUT PIN ON HEADER | | 3 | NOT CONNECTED TO ANYTHING / CUT PIN ON HEADER | | 4 | NOT CONNECTED TO ANYTHING / CUT PIN ON HEADER | | 13 | NOT CONNECTED TO ANYTHING / CUT PIN ON HEADER | | 14 | NOT CONNECTED TO ANYTHING / CUT PIN ON HEADER | | 15 | NOT CONNECTED TO ANYTHING / CUT PIN ON HEADER | | 16 | NOT CONNECTED TO ANYTHING / CUT PIN ON HEADER | ## Libraries Used ### Local These libraries are used by the project and contained in the ```src/``` folder local to the project. ### External These libraries are used by the project and can be installed via the Arduino IDE library manager. - [CircularBuffer](https://github.com/rlogiacco/CircularBuffer) ## Implementation (Incomplete) - FRAM break out for configuration persistence - Fall back to saved config *and* goes into stand alone via usb port *if* it's not seeing the main board - Receive configuration over i2c - Save configuration to FRAM - FRAM config reading - Ability to have USB *and* i2c for the UART output - Use ring buffer @ 16k for i2c - Send direct to USB and then add to ring buffer (always send over usb even if not used) ## Implementation (Complete) ## Building / Uploading The ```make.ps1```, ```build.ps1``` and ```upload.ps1``` scripts can be used to build/upload this project. These scripts call the ```arduino-cli``` commands programatically.