Difference between revisions of "Add a Serial port to the PowerPC Linkstation"
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== Stage 4 - The Serial Converter ==
== Stage 4 - The Serial Converter ==
Revision as of 13:30, 18 August 2007
The console is the text output device for system administration messages. These messages come from the kernel, from the init system and from the system logger. On modern small computers the console is usually the computer's attached monitor and keyboard. The LinkStation, however, doesn't have monitor output; instead, it uses a serial connection for console output. Not only does the serial console provide valuable debugging output, it also allows root access!
Also look at: How to attach a serial port to the Kurbox/KuroboxHG
- (1)Electronic-grade soldering iron
- (1) 0.015", 1 oz silver-bearing solder
- (1) Desolder braid, solder sucker, or Servisol Soldamop
- (1) 0.1” series PCB header plug, 4-way
- (1) Serial converter (or build your own - see Stage 4)
- (1) Tweezers
- (1) Anti-static wrist strap
Stage 1 - Access the Board
- Disassemble the LinkStation.
- Remove the main circuit board by removing the 4 mounting screws:
- Place the circuit board on a static-free work area:
Stage 2 - Attach Header to the Board
- The console header needs to be attached to the J1 pad:
- Remove the preexisting solder from J1:
- Solder the PCB header to J1 so that the pinouts face towards the IDE header
Stage 3 - Enable Full Serial Tx/Rx
- To enable write support across the serial port, remove the 10K ohm pullup resistor from R75 and install it , or another 10K ohm pullup resistor, to R76.
To desolder an SMD resistor you can apply the following trick:
- Take a short piece of blank wire and bend one end into a small U-shape using some small pliers. The U-shape should be as such that you can touch the sides of both ends of the resistor at the same time. The width of the U should basically be the length of the resistor.
- Wrap the other end of the wire around the tip of your soldering iron - while it is still cold. You now have a small U-shaped tool to remove the resistor.
- Heat up the iron. When the wire is hot enough, heat up the solder at both ends of the resistor and gently pull the resistor away from the pads with the U-shaped tip. Be careful, the resistor likes to end up on the floor.
Stage 4 - The Serial Converter
The serial port signals from the processor are only 3.3V. For proper RS-232 12V signaling, an RS-232 level shifter needs to be added. These are very common in PDA serial cables also, but can be purchased
Build your own LVTTL/RS232 or LVTTL/USB interface
- LVTTL/RS232 - Building a Custom Serial Interface
- LVTTL/USB - Use a Nokia Serial Cable on an ARM9 Linkstation
- LVTTL/USB - Use a cheap phone sync cable with the serial port
Buy your own TTL Level Shifter
- LVTTL/RS232 - MAX232 based from Futurelec - MINIRS2323V
- LVTTL/USB - FTDI chip based cable - TTL-232R-3V3
Usage considerations for the TTL-232R-3V3
A working/tested pinout/wire-color scheme is:
- Solder the 4-pin header to the board. Make sure you don't have shorts.
- You will need to switch wires on the TTL-232R-3V3 cable. Use a sharp object to lift the plastic tabs and carefully pull the wires out. Rearrange them according to the table above (black, empty, orange, yellow, empty, empty) and slide those wires back in. Tape the other wires to make sure they don't short anything.
- When plugging in the cable, make sure black aligns with GND, yellow with TXD, and orange with RXD.
- Connect the USB cable to your computer, start a terminal program with the right settings.
- Turn on the device, you should see output from the bootloader in couple seconds.
Stage 5 - Using the Serial Console
- You may access the serial console using Windows HyperTerminal (included with Windows) or [TeraTerm Pro].
Serial Port Settings