SamsungE810Cable
Contents |
Before you start
There are more than just only one revision of the serial cable descibed below. Please check if you have a newer revision (3.0 written by LordLoetkolben) of the Samsung E810 serial cable. This guide here describes revision 1.0 which might not be sold anymore.
(See SamsungE810USBCable if you are looking for the USB version.)
How to solder a Samsung E810 serial cable for use with the gp2x.
Nubie on the gp2x forums: [1] Found out that the Samsung E810 serial data cables already contained the serial level converter chip necessary to create a gp2x serial cable. Using some excellent instructions he PM'ed to me I managed to build one myself. Here are some instructions to do this, with pictures to clarify the situation.
These cables are available fairly cheaply from ebay and various other places on the web. I ordered mine from ebay and they arrived in about 2 weeks. You can plug the serial side of the cable into a serial port and measure the voltage across the 0V and 3.3V lines to make sure you have the correct cable (should register around the 3V mark).
Materials required
- A decent soldering iron (very fine tip)
- Flux cored solder.
- Some thin single core wire (kynar could be used, but I used single core telephone cable wire, or scooby wire as we call it in South Africa!).
- Xacto knife (or similar, to cut a trace on the pcb)
- Super Glue or 5 minute epoxy
Procedure
Open up the DB9 connector end
Open up the female DB9 (RS232 serial connector) end of the cable and write down the label for each wire.
You will not be soldering at all on the serial end of the cable but you might want to leave it open to check the labeling of the wires as you go along.
If your wires are not labeled on the serial side, you may be able to infer what signal each one carries by referencing their possitions on the PCBs to pictures on this page.
The colours and functions of the wires (on my cable) were:
- Red : 3.3V
- Black : 0V
- Green : TX
- White : RX
- Blue : CTS
- Yellow : DTR
Open up the EXT connector end
Open up the connector shell on the EXT end of the cable, you will find the same 6 wires connected to a small circuit board.
TODO: Post pics of 'original' cable before desoldering.
- Remove the circuit board from the shell.
- Desolder the six wires from the board.
- Orient the board as if you were going to plug it into your gp2x.
You should notice that the pin numbering on the Samsung connector is the inverse of the one in the wiki: EXT_Port.
I am using the pin numbering as per the EXT_Port documentation, NOT the pin numbers on the Samsung PCB.
- The three right most pins on the top of the connector (pins 20, 22 and 24 of the EXT Port) should be wired to 3.3V, TX, and 0V (Red, Green, and Black).
- The left most pin on the bottom of the connector (pin 23 of the EXT Port) should be wired to RX.
Note: TX on the serial cable connects to RX on the gp2x, and RX on the serial cable to TX on the gp2x.
Soldering the pins
Cut 4 strips of single core wire about 2-3cm long and solder them to the pins shown above:
- Strip and tin the wires.
- Put a small amount of solder on the pins (be CAREFUL, too much solder will 'run' up the pin and could cause a short).
- Solder the wires to the pins by placing the wire on the pin and heating it with the iron.
- Cut the track on the bottom side of the connector as shown in the image.
Method:
I used the single core wire (as opposed to soldering the actual cable wire directly onto the pins) for the following reasons:
- The single core wire is stiff and as it is single core, is a lot easier to solder to the small pins on the connector.
- The single core wire can be easily glued to the PCB, and if you are not too confident a solderer, you can glue the wire to the PCB before soldering (make sure you have tinned the wire, and prepped the pins first!)
- The quality of the cable wiring after desoldering it from the PCB is not great, in fact you usually have to trim and prep the wires. This also caused the wires to shorten, which in turn means they are not long enough to reach the pins.
When you have done this you should end up with something like the images to the right. Please be aware that the colours of the single core wire I have used in this image bear NO RELATION to the colours of the wires in the cable!
- Use the Super Glue to glue the single core wire to the board (this will stop the pins moving and possibly touching).
- Cut each wire so that about 1/2cm extends over the board.
- Strip and tin the end of each wire.
- Solder the wires from the EXT cable (Red, Black, Green, White) to the respective single core wire.
- Insulate each connection with some shrink wrap or insulative tape.
- Put the board back into the shell, put it all back together, close it up and screw the shell closed.
Note: You may have to shave off some of the plastic guide ridges on the bottom side of the Ext connector with your Xacto knife to get it to fit into the GP2X Ext Port. You can see where this has been done if you look closely at the pictures to the right.
You are now the proud owner of a gp2x serial cable!
--Sweetlilmre 03:39, 21 February 2006 (PST)
Testing the cable
The first time you jam the EXT end into your gp2x some plastic will be shaved off the connector. You may want to shave the plastic off with an exacto knife before jamming it in, to avoid the chance of bending the gp2x serial connector out of shape.
The DB9 end of the cable belongs in your PC.
If your cable is connected and you have a Try out the serial terminal connection up on your pc, booting the gp2x should scroll some data across your screen.
Troubleshooting a serial connection
- check the cable is properly inserted on both ends
- try another serial port on your computer (if you have more than one)
- check your terminal settings
- check your wiring/soldering job
