For any discussion not specifically related to your project
By SilentBob
#48829
Just curious has anybody had any problems powering either the mega or a teensy from VIn and usb at the same time?

In another project I used a teensy 3.6 and had all kinds of issues with external power and usb being used at the same time.
By dazq
#48837
SilentBob wrote: Mon Mar 08, 2021 6:05 am Just curious has anybody had any problems powering either the mega or a teensy from VIn and usb at the same time?

In another project I used a teensy 3.6 and had all kinds of issues with external power and usb being used at the same time.
You must NOT power a teensy from vin and usb at the same time. See the pjrc site for details on cutting the power link or making the diode modification
By SilentBob
#48839
dazq wrote: Mon Mar 08, 2021 10:58 am You must NOT power a teensy from vin and usb at the same time. See the pjrc site for details on cutting the power link or making the diode modification
fram wrote:As previously said, You must NOT power from vin and usb at the same time.
From most of the MEGA2560 boards, it's easy to cut VUSB as removing the fuse close to USB connector.
Yep am well aware that they shouldn't be used together, just haven't seen it mentioned anywhere else or on any of the designs so thought it was worth posting a topic for people who aren't aware.
User avatar
By PSIG
#48842
PSIG wrote:
Torslund wrote: ↑25 May 2020 02:06
Suddenly stall that occurs now and then can USB related.
Cool. 8-) There are several threads on how to fix USB power errors. Some simply remove the USB power PTC fuse (gold and black thing by the USB port on a Mega) so it only communicates data. Others like to use two USB cables, one with power for 5V bench testing, and one without power for tuning. There are other solutions. Do your thing.
By kettlekev
#48931
Power things is a related issue and cutting the 0v line helped that but then it didnt help sync loss issues.

I had loads of sync loss issues and eventually got the main culprit down to the USB cable picking up noise.

Corrections were;

1. Buy good quality cable
2. Use as shorter a cable as possible
3. If you are still having issues then add ferrites into the USB cable. Some cables come with them anyway (black blob the cable passes through). I needed 3 on my not so good cable.

And obviously sort where it is coming from in the first place, starting at restive plugs and caps.

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