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.
On Sat, 15 Mar 2025 17:30:03 -0000 (UTC), bp@www.zefox.net wrote:I'm trying to figure out if I can talk to the controller
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)
2. What do you have to work with? (maker, model, versions, photos,Owon vds1022i usb scope, 100Ms/sec, likely 10 MHz bandwidth. Board
URL's)
3. What have you done so far and what happened?Connect the 'scope, power cycle the inverter, look for traffic on Tx.
4. What is your ability or experience level?Retired experimental physicist, from the pre-digital epoch.
5. Optional - All the background data and history.The inverter behaved strangely (but usably) when acquired. Eventually
End Mini_Rant()
Jeff Liebermann <jeffl@cruzio.com> wrote:
On Sat, 15 Mar 2025 17:30:03 -0000 (UTC), bp@www.zefox.net wrote:I'm trying to figure out if I can talk to the controller
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)
2. What do you have to work with? (maker, model, versions, photos,Owon vds1022i usb scope, 100Ms/sec, likely 10 MHz bandwidth.
URL's)
Board images are at
zefox.net/~bp/ampinvt/2nd_inverter/board_photos
It sure doesn't look like a USB port to me. If it is, my scope is blind.
3. What have you done so far and what happened?Connect the 'scope, power cycle the inverter, look for traffic on Tx.
4. What is your ability or experience level?Retired experimental physicist, from the pre-digital epoch.
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?
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.
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.
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>
Are there any customary tricks to making a diagnostic serial port
active?
On Sat, 15 Mar 2025 17:30:03 -0000 (UTC), bp@www.zefox.net wrote:
Are there any customary tricks to making a diagnostic serial port
active?
I am not aware of any standards.
Some devices will respond to a few CR-LF, as in pressing the enter key
a few times, but those are probably mostly intended to be accessible
by the user.
A device like this may very well have the serial port disabled in
firmware.
HW <none@no.no> wrote:
On Sat, 15 Mar 2025 17:30:03 -0000 (UTC), bp@www.zefox.net wrote:
Are there any customary tricks to making a diagnostic serial port
active?
I am not aware of any standards.
Some devices will respond to a few CR-LF, as in pressing the enter key
a few times, but those are probably mostly intended to be accessible
by the user.
A device like this may very well have the serial port disabled in
firmware.
I did briefly try to connect a usb-serial adapter, hoping to see at
least garbled boot messages during power up by varying baud settings.
Nothing at all appeared on the terminal screen. That's when I tried
the 'scope and found nothing.
There are some board photos at http://www.zefox.net/~bp/ampinvt/2nd_inverter/board_photos/
Please note it's http:..., not https. You'll have to pacify
your browser if it doesn't like unencrypted connections.
I'm not seeing an MCU, although it could be underneath or on another board.
Theo <theom+news@chiark.greenend.org.uk> wrote:
I'm not seeing an MCU, although it could be underneath or on another board.
It turns out there is an smd package with at least 40 pins on the >perpendicular daughter board at the lower of the photo at >http://www.zefox.net/~bp/ampinvt/2nd_inverter/board_photos/IMG_0007.JPG
It's only about 10 mm square, so any markings are going to be tiny.
Unfortunately it's on the side that can't be seen in the photo. It's
mounted diagonally, as one sees on images of SBCs. I've tried to get
a look at the package markings but can't make them out vi a dental
mirror, too much stuff in the way. The packaging is rather tight, so >improving the view won't be easy 8-(
Obviously it might help to identify the device. Then again, it might not.... >I'll try to figure out how to get a good look. Something like a camera >periscape the size of a pencil would be about right 8-)
I'm hesitant to
start taking things apart because the device is still usable, if not
entirely perfect.
10 mm body might be a QFP64 package. <https://www.amazon.com/programming-machine-Size10x10mm-12x12mm-FPQ-64-0-5-06/dp/B0757JNQR4>
Try an endoscope camera: <https://www.ebay.com/sch/i.html?_nkw=endoscope+camera&LH_PrefLoc=1>
They comes in 5.5, 6, 7 or 8mm dia probes. 7mm seems to be a good
compromise between viewing angle, depth of field and illumination.
If you leave it torn apart, you'll eventually lose some parts or
hardware which potentially will make it useless. That's what recently happened to me with a Chinese 12VDC to 115VAC power supply. Best to
make your decision fairly soon.
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. This piqued my curiosity, so I connect a 'scope
to the Tx pin and Gnd, then tried power-cycling the inverter a few
times. Several power cycles later I could find no hint of a signal
anywhere near the usual 9600 baud rate that I believed customary.
Are there any customary tricks to making a diagnostic serial port
active? Most of the silkscreen is in English, so there might be
an enable/disable jumper position if I could recognize it.
The manufacturer is actively unhelpful on sincere questions, so
this kind of inquiry won't be taken kindly. Some sources indicate
the inverter brand (ampinvt) is a knockoff of a Sigineer design.
I was unable to locate technical information of either of them.
The inverter-charger works acceptably but sometimes behaves oddly,
I'd like to explore the control parameters if it's possible.
Thanks for reading, and any ideas.
bob prohaska
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. This piqued my curiosity, so I connect a 'scope
to the Tx pin and Gnd, then tried power-cycling the inverter a few
times. Several power cycles later I could find no hint of a signal
anywhere near the usual 9600 baud rate that I believed customary.
Inverter/chargers are often provided with a basic communications
method, if only to turn off and on remotely.
These can use any com hardware or protocol mixed and matched
to do the job - usb sockets spouting rst232, network connectors
doing the same.
Theo <theom+news@chiark.greenend.org.uk> wrote:
I'm not seeing an MCU, although it could be underneath or on another board.
It turns out there is an smd package with at least 40 pins on the perpendicular daughter board at the lower of the photo at http://www.zefox.net/~bp/ampinvt/2nd_inverter/board_photos/IMG_0007.JPG
It's only about 10 mm square, so any markings are going to be tiny.
Unfortunately it's on the side that can't be seen in the photo. It's
mounted diagonally, as one sees on images of SBCs. I've tried to get
a look at the package markings but can't make them out vi a dental
mirror, too much stuff in the way. The packaging is rather tight, so improving the view won't be easy 8-(
Obviously it might help to identify the device. Then again, it might not.... I'll try to figure out how to get a good look. Something like a camera periscape the size of a pencil would be about right 8-) I'm hesitant to
start taking things apart because the device is still usable, if not
entirely perfect.
bp@www.zefox.net wrote:
Theo <theom+news@chiark.greenend.org.uk> wrote:
I'm not seeing an MCU, although it could be underneath or on another board.
It turns out there is an smd package with at least 40 pins on the
perpendicular daughter board at the lower of the photo at
http://www.zefox.net/~bp/ampinvt/2nd_inverter/board_photos/IMG_0007.JPG
It's only about 10 mm square, so any markings are going to be tiny.
Unfortunately it's on the side that can't be seen in the photo. It's
mounted diagonally, as one sees on images of SBCs. I've tried to get
a look at the package markings but can't make them out vi a dental
mirror, too much stuff in the way. The packaging is rather tight, so
improving the view won't be easy 8-(
Obviously it might help to identify the device. Then again, it might not.... >> I'll try to figure out how to get a good look. Something like a camera
periscape the size of a pencil would be about right 8-) I'm hesitant to
start taking things apart because the device is still usable, if not
entirely perfect.
A rough rule of thumb is if you can see a DRAM package (likely to be a BGA) and some storage (NOR/NAND/SPI flash) then there's a good chance it's
running Linux and the serial port will give you messages from the bootloader if nothing else. If it just has an MCU then it's likely running bare metal firmware and I'd not expect to see anything out of the UART, although it wouldn't hurt to probe it and confirm.
The fact the power is 5V and not 3.3V does suggest it's more likely to be an MCU.
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