Problem Connecting via Serial
I am trying to connect to my Omega2 (on Expansion Dock) from a Windows 10 PC.
Downloaded and installed the CP2102 driver, apparently successfully.
Downloaded PUTTY, installed fine.
Had to search a bit, but located a USB-A Male-to-Male cable.
The Omega2 is powering off the USB-A port (I accidentally dislodged the micro-USB, and it stayed up), but Windows will not register any USB device when I connect them. Only shows COM1, already on the PC. No CP2102, or COMx for x>1.
Any thoughts as to what's wrong?
Do I need some sort of USB crossover cable, with Tx and Rx swapped?
@dbell USB-A doesn't provide serial terminal connection, only the micro USB.
@crispyoz I completely misread that! Thanks for the correction.
Now, any ideas why I can't find a new COM port?
The PC I'm using is a relatively new one, from an Amazon upgrade vender.
It has a 9-pin serial port connector, but I've never verified if it's actually implemented. Device Manager shows only COM1 (and no reference to CP2102), and connecting to COM1 with PUTTY at 115200, I don't get a CLI prompt, or anything else. I suspect it's talking to the DA9; maybe tonight I will jumper Tx to Rx to verify that.
@dbell Are you connecting the PC to the micro USB of the Omega2?
@jossvall Well, yes.
To clarify, I started out using the micro USB on the Omega expansion dock.
I misunderstood, believing that I needed to connect the PC USB to the USB-A jack, to use the serial port for command line direct access.
With the USB-A cable or without, I can't get a CLI prompt using COM1 at 115200 baud.
No problem connecting over the network to the Omega, but since I want to modify the web server, I don't want to do that without the direct port access.
Chris H last edited by
@dbell You need a USB A to Micro-USB (or in millennial language a "Android Charger") cable. When plugged into to PC it should appear as additional COM port in device manager. If not then your cable might truly be a charge-only cable with no data connections, or there's a fault with the dock.
The only physical UART (serial) connections are on the dock expansion connector. Additionally you'll need voltage level translator/interface circuitry before you can connect this tot he PC serial port (which will use RS232 levels).
@dbell Well let's go in parts,
You mentioned that your PC has a serial port which has a DB9 connector, Be careful that this connector is RS232 which is very different from TTL, you can cause damage to the omega if you connect it directly.
Most likely that COM1 refers to the native serial of your PC.
In the device manager of your PC do you see more COM ports apart from COM1?
do you have unknown devices?
@jossvall Yes, I understand the RS232 vs. TTL issue!
I was expecting to find the CP2102-based COM port, but it doesn't show up in Device Manager.
No Unknown Devices, either.
@dbell This seems to be getting over complicated.
You need a USB A to USB micro cable as Chris H said. When you plug that into your computer and connect it to the expansion dock Windows should find a new com port. If it doesn't then there is an issue with your cable or the expansion dock.
I think messing around with the DB9 is just digging yourself a hole.
@crispyoz No, I'm not messing with the DB9 serial port, that's clearly not what needs to connect to the Omega.
I am using the Omega-supplied USB-A-to-micro USB cable that came with the Omega and Expansion Dock.
I suppose it's possible the cable is bad, but it does provide power fine. I'll try another cable, for sure.
Any idea how to tell if there is a dock problem?
I'm most concerned about the PC not registering the USB device and creating a new COM port at this point.
@dbell The dock doesn't come with a cable, so maybe someone bundled it for you.
Just as windoze is designed to detect any hardware you plug in, it will detect the CPxxxx once the dock is connected. If it doesn't then it suggests a hardware issue, either the cable or the dock. Are you sure you have an expansion dock, not a power dock? Power Dock doesn't have the USB - UART chip.
Do you have any "Unknown device" in your device tree on windoze? you may have a driver issue. Remove the device and then plug in your dock and see if it re-adds it.
If you have more than one USB port on your computer is worth trying each of them, my ThinkPad has a USB port on the rear that seems only to work with some devices, then 2 others on the side that work with everything. Not sure why, can't be bothered to look at it
@crispyoz Hmm. Now I think of it, I may have used a cable I already had. If so, it's possibly a "charge only" cable.
Otherwise, no Unknown Devices, and definitely an Expansion Dock. The UART/USB chip is present.
Thinking about "bundles", when I ordered the Omega and the Dock, add-ons were the 40-pin GPIO cable, 32GB SDCard, and microSD.
The SDCard has the Rasperry PI logo; is that a system distro, for re-flashing?
And what is the microSD for ?
@dbell Not sure why you would receive a sdcard with a pie logo on it. This is not an Onion offering, maybe something your retailer bundled so I have no idea what would be on it.
@crispyoz Sorry, brain fart!
Comes from unboxing two devices the same weekend...
I ordered an RP-400 about the same time. Pretty nice package, with a complete Linux box in a compact keyboard. That had all those accessories...
@crispyoz Well, having a complete, functioning cable is the key!
Amazon one-day to the rescue.
As soon as I plugged it in (still powered through the USB-A port) it registered as COM3.
Unplugged the -A and brought up the CLI in PUTTY,,,
Thank you for the patient assistance!
@dbell Happy to hear it's working now. A very long and twisted road to get there.