Add Serial Port

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Revision as of 00:40, 23 June 2007 by IqzPia (Talk)

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WARNING!

There is a possibility that you could brick your NAS with these instructions. Please make sure that you read the entire page carefully. Adding a serial port requires soldering onto the Kurobox main board and can cause catastrophic failure to the hardware.


Contents

Getting Started

Locate J1 on the Mainboard

Locate J1 on the Mainboard after removing it from the case. This should be a 4 pin unpopulated header. The easiest way to find this is to first find the CPU first, and then look near the corners for J1.

Attach the serial port

J1 Pinout
Pin Signal
1 Transmit (TX)
2 Receive (RX)
3 Power (3.3V)*
4 Ground (GND)

The manufacturer of the Kuro filled the jumper holes for the Serial port with solder. Removing the solder from the jumper holes on the Kuro board is simple.

  • Press the tip of a 15 watt soldering iron with a good sharp tip (if the tip isn’t sharp use a file to sharpen it and tin the tip) into the hole from the back of the circuit board.
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WARNING!

THIS IS VERY IMPORTANT. IN THE NEXT STEP THE BOARD SHOULD BE BETWEEN THE SOLDERING IRON AND YOUR MOUTH. FAILURE TO PLACE THESE THREE OBJECTS IN THE CORRECT ORDER WILL RESULT IN EXCESSIVE PAIN.


  • When the solder is flowing nicely, get your mouth about 1" from the front of the board and blow hard into the wet solder while at the same time removing the solder iron. You will blow the solder out of the hole leaving a hole that you can easily put a wire through.

Single or Bi-directional Traffic?

To allow one-way serial port traffic (read only) you can just add the 4 pin header and be done. To enable bi-directional serial port activity, you must also add a 10K resistor as described below.

Enable Write Mode (optional)

This step is optional, but you might find that the serial port is more useful with bi-directional traffic. To enable write support across the serial port, remove the 10K ohm pullup resistor from R75 and solder this, or another 10K ohm pullup resistor (SMD package size is 0603 if you want to buy one), to R76.

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TIP

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.

Level shifter

The serial port signals from the processor are only 3.3V. For proper RS-232 5V signaling, an RS-232 level shifter needs to be added. These are very common in PDA serial cables also, but can be purchased from Compsys Bench or Digital Nemesis

Item Name: A232DBH3v Max232 3.3v ver. adapter assembled w/hood kit 
Item Number: A232DBH3v 

As an alternative you can make the level shifter cable yourself: [http://www.type-g.com/index.php?plugin=attach