Adding a serial port
From NAS-4220
Contents |
Adding a serial port to the Taurus LAN
Disclaimer
These instructions are for adding a serial port to the MacPower Taurus LAN network attached storage enclosure. While the NAS-4220 appears to share the same hardware this hasn't been confirmed. Please do not assume that the pin outs are the same. As always do not attempt this unless you know what you are doing.
Why add a serial port?
- Local access to your NAS in the event that you are unable to connect via the network
- Shell access as the Taurus LAN firmware does not provide a ssh or telnet server
- Uploading custom firmware and kernels images
- Recovery from the uploading of custom firmware and kernel images ;-)
Let's get hacking
On the Taurus LAN the serial port lines are exposed by the J2 connector (shown below). This was discovered by probing with an oscilloscope and rebooting the NAS several times.
RS232 and TTL
As these serial lines use TTL logic levels (0 -> 5V) they need to be converted to RS232 levels to work with a standard PC serial port. There are many ways to go about doing this and the choice is typically based on what components are most easily available. A very simple and cheap circuit is shown below for convenience but is by no means mandatory. This circuit was designed by Dale Botkin, and further details can be found at http://www.botkin.org/dale/rs232_interface.htm
- X1
- PC serial port
- PIC_TX
- Transmit line from the NAS to the receive port on the PC
- PIC_RX
- Receive line to the NAS from the transmit port on the PC
J2 pin outs
Peeling back the protective plastic insulator you can attach wires as shown below. Keep in mind that the hard drive sits on top of this connector so a low profile connection is important.
- RxD
- Is PIC_RX in the circuit above and ends up connecting to the TxD pin on the serial port.
- TxD
- Is PIC_TX in the circuit above and eventually connects to RxD pin on the serial port.
Finished
Serial terminal
Connection uses 19200 8N1
Storlink SL351x Boot Loader [Linux], version 1.0.9
Built by linux, 17:55:15, Jul 11 2007
Processor: SL3516c2
CPU Rate: 300000000
AHB Bus Clock:150MHz Ratio:2/1
MAC 1 Address: 00:01:D2:01:D2:10
MAC 2 Address: 00:50:C2:2B:D0:02
inet addr: 192.168.1.102/255.255.255.0
==> enter ^C to abort booting within 3 seconds ......
Load Kern image from 0x30020000 to 0x1600000 size 1583204
Load Ramdisk image from 0x30320000 to 0x800000 size 2359296
Uncompressing Linux............................
8<-- SNIP! Kernel boot messages 8<--
Please press Enter to activate this console.
BusyBox v1.8.2 (2008-07-27 10:10:11 NZST) built-in shell (ash)
Enter 'help' for a list of built-in commands.
_______ ________ __
| |.-----.-----.-----.| | | |.----.| |_
| - || _ | -__| || | | || _|| _|
|_______|| __|_____|__|__||________||__| |____|
|__| W I R E L E S S F R E E D O M
KAMIKAZE (bleeding edge, r10634) -------------------
* 10 oz Vodka Shake well with ice and strain
* 10 oz Triple sec mixture into 10 shot glasses.
* 10 oz lime juice Salute!
---------------------------------------------------
root@FlatBed:/# uname -a
Linux FlatBed 2.6.15 #2 Sat Aug 2 17:25:24 NZST 2008 armv4l unknown
root@FlatBed:/#
