Should there be a low Ohm resistor between P1 and P7? Maybe 100 Ohm? Just in case an external USB 5V has a difference between the P1 VIN.
It depends what you are trying to do and what you are worried about.
I would not recommend trying to power it from both USB and External 5V with Pin 1 and Pin 7 shorted. That is just a work-around to keep it running when powered from external +5 V.
I am just worried about somebody powering from Vin and Vusb simultaneously.
I have seen crazier things happen. Seems like a safety net. ID10T thing.
Here’s an example. PB is powered by external 5V through Vin. Then, user hooks up a powered USB hub to Vusb interface to hook up peripherals through the USB hub. Not an unreasonable scenario.
Nothing that I would do of course!
Yes it is a real world scenario.
I don’t recommend you do it unless you are really knowledgeable in the way that USB power works, and are willing to accept the consequences if you do it wrong.
A 100 Ohm resistor is way too high to power a PocketBeagle through.
If you make it low enough to cross-feed power between the pins, then it is too low to prevent problems.
Rather than design a circuit that will allow it to work safely under all circumstances, I suggest the PMIC and control software in the PocketBeagle get fixed, so it works as well as, and just like a BBB. It is supposed to be the same base parts.
In the meantime, I suggest that shorting Pin 1 and Pin 7 be restricted to use as a workaround, in the event you need to power a PocketBeagle from 5 Volts only, and not plug in a USB source of power at the same time, or defeat the USB power lead if you do need to plug in USB for control/communications.
We are seeing something similar on a board we designed using USB1 host. We have PB powered through VIN, with P1.7 floating and are seeing spurious reboots a few times per day. We are running on latest 9.5 image.
Our initial thought was that it was related to our 5V supply on Vin, and were going to start adding capacitance, and doing some testing based on this line of thought, but it seems you’ve already been down this road and it did not have an impact. Have there been any new findings since July? If not, have you found the P1.1<=>P1.7 to be stable? In our case this would be fine since we remove the uUSB connector anyway.
**If not, have you found the P1.1<=>P1.7 to be stable?
It has worked for me. No more random reboot after this.
I’m working in a clone board using the same IC as the PB, when they arrive i will test stability powering from VIN and VUSB.
I have than this test on the BBBW and not detect any issue, although the ICs are not the exactly same ( OSD335x vs OSD335x-SM).
Has anybody powering the OSD335x-SM from VIN with no stability problems?
Can I power the PB with 5V on P1-7 and disconnect P1-1?
I plan to use the USB port for a wifi.
I have not used a PocketBeagle in several years, so my memory might be in error.
I didn’t do any extensive testing with power only on P1-7, but as I remember, I never saw any unexplained resets when powered from P1-7 only.
When power is applied simultaneously to both P1-1 and P1-7, the unit is definitely stable.
When you say you plan to use the USB Port for a WiFi …
As I remember the Pocketbeagle has two USB ports. USB0 pinned out to the micro-USB connector, and USB1 pinned out to P1- 3, 5, 7, 9, 11, 13.
USB0 is commonly used for USB “client” functions, such as the memory-drive that shows up on the host computer.
USB1 is commonly used for USB “Host” functions, such as a Ethernet or WiFI interface.
You can use USB0 for host functions, refer to:
You may find it easier to use USB0 for connection to the host, and USB1 to interface to your WiFi dongle, but this will require wiring a USB adaptor to the USB1 connections on P1.
I plan to use USB1 for the wifi. I have bread boarded that and it works well. I’m making a pcb which will bring out the USB1.
Thanks for the help.
I’m going to wire them together.
I plan to run both on a 1s battery and 5 volts for shore power.
There is a separate battery power input, (P2-14) designed for a single cell battery, with its own dedicated switching converter.
Whereas the J1-1 and J1-7 inputs are intended for 5 Volt input.
They may or may not work well with a 3.7 Volt input.
I don’t have any personal experience running off a single cell battery, but I would at least try a multiple day run with the battery on the battery input.
Will the WiFi run off of 3.7 Volts?
I plan to use the battery input for a 1S battery.
The beaglebone blue also has one for 2S batteries which I have also used.