Re: Waking up a serial port

On Sun, 16 Mar 2025 00:50:18 -0000 (UTC), bp@www.zefox.net wrote:

Jeff Liebermann <jeffl@cruzio.com> wrote:

On Sat, 15 Mar 2025 17:30:03 -0000 (UTC), bp@www.zefox.net wrote:
 

While looking around inside a 12 volt to 120 volt inverter charger
I noticed a pin header labeled "5v Rx Tx Gnd" near the edge of the
main circuit board.

 
That sounds more like a USB-A connector pinout:
<https://components101.com/sites/default/files/component_pin/USB-Type-A-Connector-Pinout.jpg>
 
See if there's any data on the Rx pin.
USB data runs at 12 to 480 Mbits/sec.  What's the maker and model
number of your oscilloscope?  What's the scope bandwidth?
 
If the connector is USB, the data is differential between the + and -
pins (which may be the Rx and Tx pins).  RS-232 is specified at
+/-15VDC.  It's possible for it to operate at 5VDC.
 
<https://www.testandmeasurementtips.com/measuring-universal-serial-bus-usb/>
 
The inverter manufacturers name and model number would also be
helpful.  Good luck.
 
Begin Mini_Rant()
1.  What problem are you trying to solve?  (Keep it simple)

I'm trying to figure out if I can talk to the controller

2.  What do you have to work with?  (maker, model, versions, photos,
URL's)

Owon vds1022i usb scope, 100Ms/sec, likely 10 MHz bandwidth.

<https://www.owon.com.hk/products_owon_vds_series_pc_oscilloscope>
See table near bottom of page.
Bandwidth for vds1022i is 25 MHz.  You should be able to see USB data.

Board images are at
zefox.net/~bp/ampinvt/2nd_inverter/board_photos

<https://zefox.net/~bp/ampinvt/2nd_inverter/board_photos>
The web server or load balancer is returning "Server not found".
I tried various variations with no improvement.  Please check the URL.

It sure doesn't look like a USB port to me. If it is, my scope is blind.

The wiring order and designations sure look like USB to me:
<https://www.testandmeasurementtips.com/wp-content/uploads/2017/03/USB-pin-outs-1.jpg>

3.  What have you done so far and what happened?

Connect the 'scope, power cycle the inverter, look for traffic on Tx.

Is there +5VDC on the 5v pin?
Try using the scope in differential mode. 
Channel A to + and Channel B to - with the scope looking at (Ch A
minus Ch B).

https://www.sciencedirect.com/topics/computer-science/differential-signaling

4.  What is your ability or experience level?

Retired experimental physicist, from the pre-digital epoch.

Ok.  I'll adjust my vocabulary to minimize digital technobabble.

5.  Optional - All the background data and history.

The inverter behaved strangely (but usably) when acquired. Eventually
I replaced it with another unit and would like to understand what ails
this one if it isn't too difficult. It's still usable as a spare, so
I'd rather not damage it.
>
My working guess is that the software is misconfigured. The vendor's
behavior was completely obfuscatory (if that's a word) so I'm not asking
them for anything. Their products are sold cheaply enough that buying
three to get two that work was still the best deal available.
>

End Mini_Rant()

>
Thanks for writing,
>
bob prohaska

I need some time to chase the vague references to the possible maker
of the inverter (Ampinvt and Sigineer).  Got any better info?  Photo?

If the inverter was working (strangely), I suspect you might get some
clues by looking at the output waveform with your oscilloscope (in
differential mode).  You can do some amazing things with software, but
trashing the AC output waveform is not one of them.  However, acting
strangely (whatever that means) is possible. 



--
Jeff Liebermann                 jeffl@cruzio.com
PO Box 272      http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann      AE6KS    831-336-2558