Serial adapters/Arduino

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How to use an Arduino Uno as a serial adapter for an OLPC XO laptop.

Ingredients

  • an Arduino Uno, called the Arduino,
  • a computer running the Arduino development environment, called the host,
  • a USB cable to connect the Arduino to the host, normally supplied,
  • an OLPC XO laptop, disassembled to expose the serial connector, called the target,
  • a way to connect wires between the Arduino and the target (jumper leads, solder, iron, connectors, etc).

Method

  • disconnect all wires from the Arduino,
  • connect the USB cable between the Arduino and the host,
  • download passthrough-serial-adapter.ino and program it into the Arduino,
  • on the host, start a serial terminal application like screen, and verify that pressing keys causes the D13 LED to flash,
  • connect a GND pin on the Arduino to the GND pin on the serial connector of the target,
  • connect the D0 (RX) pin on the Arduino to the RX pin on the target; this carries keys from the host to the target,
  • connect the D1 (TX) pin on the Arduino to the TX pin on the target; this carries text from the target to the host,
  • turn on the target, and the boot text should be displayed,
  • press Escape key, and the Ok prompt should appear.

Diagram

Arduino-uno-serial-passthrough.jpg