For a project, I built a prototype with all electrics, sensors, Lcd and displays, and code. It works as it should. Pins used from 2 to 13, A0, GND and +5V, on a UnoR3 card (called here “My Uno”), purchased as part of an Arduino starter kit that has given no trouble.
It runs with IDE Arduino 1.8.2.
The computer is Dell Inspiron 17R-5720 (+ docking station DisplayLink to multiply the number of USB ports and display on 2 screens). Inspiron has USB2, Docking has USB3. The OS is W7 professionnal 64 bits. During the problem described here, no changes were brought to the PC, no W7 update.
To turn the prototype into definitive form, I purchased another genuine Uno card (called here “Project Uno”). I plugged the brand new “Project Uno” in and W7 told me that a new driver was being installed. So far, so good.
However, the IDE did not upload the code and gave Error message AVRDUDE: ser_open() : can’t set com-state for « \.\COM4 ». I did not think, at that stage to collect more verbose detail; they are no longer accessible.
The comparison between the two Uno cards shows
« My Uno » « Project Uno »
Card type Arduino/Genuino Uno Arduino/Genuino Uno
VID 2A03 2341
PID 0043 0043
S/N 855 393 139 313 51B 021 E1 557 363 133 383 514 162 D1
Port Com3 Com4
Driver date 19/03/2015 24/11/2015
Driver version 22.214.171.124 126.96.36.199
Supplier Arduino srl Arduino LLC
Location 0 Port #0002. Hub#0001 0 Port #0002. Hub#0001
(Sorry, couldn't format this table properly)
After reading www.arduino.cc/en/Guide/Troubleshooting, Google search, forum posts, … I went through the following checks:
- Unplug & re-plug card: no change
- Try different USB port locations on PC: no change
- Restart PC: no change
- Reset Uno card: L Led flashes ok (bootloader is ok)
- Temporarily de-activate antivirus: no change
- Connect with another USB cable: no change
- Check 5V and 3.3V power: ok
- Execute IDE as Administrator: no change
- De-activate DisplayLink & restart PC as stand-alone: no change
- Connect to a port on docking station: no change. (I realized later that this is the first time it got plugged into USB3.)
“No change” means each check was made for both cards. “My Uno” always uploads, “Project Uno” always fails with same error message. This excludes any problem with electrical contacts, USB connectors, or cable.
All this leaves me with the same questions as when I started, and without direction.
Next, the problem changes: the “Project Uno” card is not even detected anymore by the computer: no dingdong sound when plugging, USB port does not show in W7 Control Panel\Device Manager (Gestionnaire de Périphériques in French), IDE Tools\Serial Port has gone grey.
I then tried plugging into another PC (with Windows XP, totally stand-alone to avoid risk of corruption of a critical program). Same No dingdong sound and USB port does not show anywhere with “Project Uno”. “My Uno”, however, is detected and tries to install driver.
The 16U2 chip seems to be regularly accused of being weak; but I never drew any current as the card has always been connected bare, with no output, and not powered by anything but the USB cable. It was never laid on an electrically conductive surface.
Has “ProjectUno” card developed a hardware problem, in addition to an initially suspected driver problem? I absolutely want to understand & correct; if not it will obviously happen again.
Are the differences of VID, driver version, driver date, … significant? If so, how should they be taken care of?
Has the card been damaged? If so, why? How can this, hardware or otherwise, be fixed?
Would a CH340 clone be better?
My thanks to anyone who would offer his help.