I designed a board with FTDI FT232R chip and ATMEGA 1284P. This prototype is working pretty well except on my laptop.
PC: HP EliteBook G1 Core i-5 4300U (2014). My laptop has 4 USB 3.0 ports, two on the left and two on the right. It sits on a dock with 3 additional ports. It's running win 7 pro 64 bit.
If I connect my prototype to the right ports or the ones on the dock, it works fine. I can upload code and communicate with it. If I connect to one of the left ports, it reports unrecognized device (device malfunctioned). There is no VID or PID so no COM port. If I connect to the other left port, the VID and PID show up correctly and the COM port appears. But if I attempt to load sketch, it throws the following error:
Arduino: 1.6.0 (Windows 7), Board: "Open source physics lab V 2.4.x"
Sketch uses 1,198 bytes (0%) of program storage space. Maximum is 130,048 bytes.
Global variables use 9 bytes (0%) of dynamic memory, leaving 16,375 bytes for local variables. Maximum is 16,384 bytes.
avrdude: stk500_paged_load(): (a) protocol error, expect=0x14, resp=0x00 avrdude: stk500_cmd(): programmer is out of sync Problem uploading to board. See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.
This report would have more information with "Show verbose output during compilation" enabled in File > Preferences.
I suspected the ports were bad so I tested it out with a nano that has CH340 TTL USB chip. The thing installs a different COM port for each port I plugged in but it works on left and right ports.
I've used this prototype on my home computer with no problem. I also have a mac from 2008 that I use for development. It has not shown any problem. I will try with a couple more laptops to see whether it is just my laptop.
Thoughts: Is it possible that these ports are damaged, or set to somehow clamp on currents and that made the FTDI chip not work?
I'll post my schematic in a bit. I will be testing