Solved USB to serial connector

B

balanga

How can I attach a console to an embedded device which only has a USB port? Presumably I can use a terminal emulator under FreeBSD to see what's going on...
 
I was talking about the physical connector. I can't really picture what I need....

On the one hand, my embedded device only has a USB connector. What would I need on the other end of the cable? In the old days you would have a serial connector which you would connect to your serial port. If I don't have a serial port do I need a USB to serial adapter? In which case I would have two USB to serial cables connected to each other.... so, I can't help wondering if there is a single cable with two USB connectors which would satisfy my needs...
 
A USB port won't be a console port unless specified. It takes a special chip onboard the device.
My server board offers a mini-USB connector for the "serial" console.
In FreeBSD it shows up as a USB Gadget device.

If this is related to your Dockstar postings you will need a TTL UART to USB cable like the Prolific PL2303 or similar. Like tingo used in your post.
There is no console over USB on 99% of devices.

There is power over USB so act wisely. You can fry components if wrong.
 
Just for a heads up many times you would not use the power from the USB-UART converter. The target device will provide power to the UART. All you need to connect is Rx,Tx and Ground. The TTL signals come in different flavors. 5V, 3.3V and 1.7V being common. This is all the more reason why not to use the power from the UART adapter. Put 5V TTL on 1.7V TTL pins and something will fry. Use no power from the UART adapter.

To that point the TTL adapter that Tingo links to has a solid header block for the output wires. This is not optimal as every embedded board has a different pinout it seems. You have to find the respective pins and connect the correct colored wire from your UART adapter. Looking at the pinouts that getopt provided[1] the pinout on the UART adapter Tingo used is different. This is from my couch as I don't have my hands on the device.
If you are slick you might be able to re-arrange the wires in the solid header pin connector. That would take finesse.

Usually these UART dongles come with separate wires for the outputs.

Here is what I use for comparison:
https://www.amazon.com/Armorview-PL2303HX-RS232-Module-Converter/dp/B008AGDTA4

[1]http://dev.shyd.de/2011/04/dockstar-serial-connection/
 
I really feel out of my depth looking at circuit diagrams and couldn't solder if my life depended on it :)...

This is all related to my 'Dockstar' postings where I've installed some Arch Linux variant and can't work out what's happening, as per advice here
https://archlinuxarm.org/forum/viewtopic.php?f=53&t=11517

Before proceeding with obtaining a 'dockstar serial connection' can anyone say if there is any chance of booting up from a FreeBSD USB image and starting up sshd....

Also, is 'dockstar' exactly the same as this http://www.seagate.com/gb/en/external-hard-drives/desktop-hard-drives/goflex-home/ since there appear to be numerous variants.
 
The color wire are not always uniform on USB-UART cables.

If you noticed from the above graphic that he uses different color wires on his UART adapter..

You want this for Prolific 2303 on the 10 pin header on dockstar by the battery:
Pin2=black
Pin4=green
Pin6=white

If you are problem prone you might want to cut the connector off the red wire or tape it up. If you use this wrongly you will smoke the component.
It is 5VDC while most TTL pins use 3.3VDC.
 
Sometimes the physical USB shell holding the connector and board comes apart at the seems. The plastic housing can be glued back together.
Can't complain for the price.
 
My USB serial connector has just arrived from China! Now to work out to break into my GoFlex Home dock....
 
OK I'm all set...I've broken into my GoFlex Home dock, connected up the black, green and white cables of my USB serial adapter to pins 2,4,6 (actually they are not pins but holes). Pin 2 is at the bottom nearest the casing... yes?

So, what's next? Plug the USB connector into one of the four USB ports (but which one?) Start some FreeBSD program with various parameters which monitors a USB port. Switch on the GoFlex Home dock and wait...
 
Once wired up plug in the UART adapter to the client machine and at the command prompt notice the text on screen.
It should show you what hardware is in use. You should look at the /dev folder before and after plugin of UART adapter.
This will show your device port.

Then run the terminal program cu to view text onscreen while the GoFlex boots up.

My Prolific UART adapter shows up as port cuaU1. So I use this:
Code: 
[CMD]cu -l /dev/cuaU1[/CMD]
Connected

Yours might be cuaU0 depending on your hardware.
 
Phishfry said:
My Prolific UART adapter shows up as port cuaU1. So I use this:
Code: 
[CMD]cu -l /dev/cuaU1[/CMD]
Connected
Click to expand...

I got that far and then nothing...After a few attempts at switching the dock on and off the light stopped flashing so I guessed I might have blown it... I could have wept after waiting three months to get this far :(
 
Also make sure the connection settings are correct, baudrate, parity and start/stop bits. Usually console ports use 9600 baud, no parity and 1 start/stop bit. But these days you'll also find 19200 baud or even 115200.
 
Phishfry said:
I doubt if you blew it if you only using Rx, Tx, and ground. Did you use the graphic for hooking up the wires?
http://www.rudiswiki.de/wiki/DockSt...chFile&do=view&target=DockStar_serial_con.jpg

Black is pin2
Click to expand...

It looks like it is still alive because I get a flashing LED when switched on without any wires connected.

The image you posted seems to have the pins the wrong way round. Here's a picture of the GoFlex base unit:-

http://images.anandtech.com/doci/3955/baseunitinside.jpg

There seems to be a '10' at the right hand of the block. So according to my understanding pin2 is at the bottom left, nearest the casing. I have connected up the black, green and white cables of my USB serial adapter to pins 2,4,6 of the dock. When switching on, nothing happens. The normal LED does not blink, and nothing gets output to the screen. When I disconnect the serial connector I can switch on and within 5 secs the LED starts blinking.

Maybe I can connect the serial connector to my Raspberry Pi to check whether it is functioning correctly, although I wouldn't know what to check...
 
Usually there is a small triangle pointing to PIN1. Sometimes it is just a rectangle printed on board under the Pin.

Well looking at that pic I see a triangle pointing to PIN1. Do you see this on the header marked J1? J1 is the header name not PIN1.
Triangle points to PIN1 and the other pinout pics I have pointed to are exactly the same.

Black is ground here:
http://dev.shyd.de/wp-content/uploads/2011/04/dockstar_J1.jpg
 
OK it looks like got the pin numbering the wrong way round... I've reverse the wires and now the dock does start flashing, but nothing gets output to the screen. Is this because of the baud rate, or maybe the connector is faulty.
 
With respect to the 2 row connectors I have seen all options of numbering the pins as
Code: 
1  3  5  7  9
2  4  6  8  10
which is the expected version. But I have seen also
Code: 
1  2  3  4   5
6  7  8  9  10
and
Code: 
1   2  3  4  5
10  9  8  7  6
Mirroring by swap of top and botton adds a factor of two. And of course there are any kind of adapter cables to make it not too obvious.
 
Success!!!!!

I swapped the green and white cables and ran:-
cu -l /dev/cuaU0 -s 115200
... and got:-
Code: 
U-Boot 2014.04.R2-1 (May 15 2014 - 14:36:05) Arch Linux ARM
Seagate GoFlex Home

(plus lots of other stuff...)

Many thanks for all the help in getting to this point. Now a new journey begins....

Finding out the mysteries of the 'GoFlexHome>' prompt.
 
I use very low cost arduino nano board as usb-to ttl 3.3V_serial converter for my rpi3 and bananaPi boards .
I cut arduino cpu and wired D0 pin as Rxd and D1 as TxD.
 
Last edited:
You must log in or register to reply here.
Back
Top