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RaspberryPI Setup

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Kaibu edited this page Jan 25, 2020 · 4 revisions

Prerequisites

  • Raspberry PI 2B, 3 or Zero (tested working)
  • 3V to 5V Level shifter
  • 220Ω Resistor
  • Some wires, (breadboard) and minimal soldering skills

Hardware

Level Shifter between 3V RPI and 5V Erika, pull-up resistor on Erika DTD.

schematics schematics on easyeda

Software

  1. To use RTC/CTS with the RPI we'll have to disable the onboard Bluetooth on the RPI3 B+ and Zero W. To do this, add this line to /boot/config.txt: dtoverlay=pi3-disable-bt If you need the serial port and Bluetooth simultaneously, check this https://wiki.fhem.de/wiki/Raspberry_Pi_3:_GPIO-Port_Module_und_Bluetooth
  2. It is also necessary to disable the system service that initialises the modem so it doesn't use the UART: sudo systemctl disable hciuart
  3. The serial port device is /dev/ttyAMA0
  4. Retrieve the device trees from https://github.com/HiassofT/AtariSIO/raw/master/contrib/rpi/uart-ctsrts.dtbo
  5. Move the uart-ctsrts.dtbo in the /boot/overlays directory. The file should belong to root and have the file permissions -rwxr-xr-x.
  6. Add dtoverlay=uart-ctsrts to your /boot/config.txt
  7. Disable the serial login shell via sudo raspi-config, leave serial hardware enabled!!
  8. Reboot.
  9. Check the settings with stty -F <device> -a. Speed should be set to 1200 baud and crtscts should be enabled (see screenshot below). Im not fix them by setting crtscts and the baud rate: stty -F <device> crtscts and stty -F <device> speed 1200, these might reset after reboot.

stty example with correct baud rate and enabled RTS/CTS

Troubleshooting

  1. double check your tty settings by stty -F <device> -a
  2. Check your solder joints, connections and wiring
  3. Use a voltmeter and/or a logic analyzer
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