Difference between revisions of "Add a Serial port to the ARM9 Linkstation"
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== The Serial Converter ==
== The Serial Converter ==
Revision as of 13:41, 18 August 2007
- 1 Introduction
- 2 Project of creating ready2use serial cables
|The same instructions will work for a KuroBoxPro|
What you can do with serial access on a LS Pro
At first: check serial access
In fact you can control the UBoot Bootloader.
- You can change to EM Mode at will without any dirty tricks.
- You can look at the linux system of your LS pro without having to flash any custom firmware
- You can load a kernel + ramdisk via tftp
- Hey! We connect it because we can!
Serial access isn`t that important for users, but it is very important for developers because they
exactly see what is happening while the LS Pro boots.
The kernel log tells us a little more about the hardware and it allows us to debug a newer kernel.
Without serial that is not possible.
Why it is easy to gain serial access on the LS Pro
Project of creating ready2use serial cables
Anyone who wants a cable please add his name to the lists below.
List of developers who want a prebuilt serial cable:
List of kurobox.com-contest winners that will get a prebuilt serial cable:
Revogear does not respond to any mails anymore, so waite decided to use the donations to buy LS Pros for these guys instead.
List of user who want a prebuilt serial cable:
Here some pictures from the build-process (mindbender had fun with it)
I opened all FutureDial Cables to check if all cables used the same color-coding + Profilic-Chip:
Prebuilt cables will use a heat-shrink-tube to make the cables more stable.
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.