A Raspberry Pi 3 Model B was used. Note that these instructions are specific to this model and may differ for other models.
### UART Setup
#### raspi-config
Under `Interface Options` > `Serial Port`, answer "No" to "Would you like a login shell to be accessible over serial?" and then "Yes" to "Would you like the serial port hardware to be enabled?".
#### /boot/config.txt
Add the following lines:
*`dtoverlay=miniuart-bt`
* Ordinarily, the Bluetooth device uses the PL011 UART (/dev/ttyAMA0); this line forces it to use the mini-UART instead. We want the PL011 UART available because it's the only one that supports hardware flow control.
*`gpio=16-17=a3`
* This line switches GPIO16 and GPIO17 to be CTS and RTS for hardware flow control.
### Connections
| PIC12F1840 Pin | RPi 3 Pin |
| -------------------- | ------------- |
| 01 Supply | 01 3v3 Power |
| 02 RA5/LocalTalk Out | |
| 03 RA4/Driver Enable | |
| 04 RA3/LocalTalk In | |
| 05 RA2/UART CTS | 36 GPIO16/CTS |
| 06 RA1/UART RX | 08 GPIO14/TXD |
| 07 RA0/UART TX | 10 GPIO15/RXD |
| 08 Ground | 06 Ground |
Driver/Receiver
---------------
While the LocalTalk bus is half-duplex, LocalTalk and PhoneNet dongles use a hybrid transformer to accommodate the SCC's separate TxD and RxD lines. Because a PhoneNet dongle was used for the prototype, a pair of SN65HVD08 were used, one as a receiver and one as a driver.
Other RS-422/485 drivers may be suitable, but it is important to experimentally verify that their receivers output a logic '1' when the bus is not being driven.
