I have around 4.6 volts on my PixHawk bus. It’s a significant drop compare to my supply when left floating (5.12v). I have some camera disconnecting issu and I am confident it is related to my Raspberry USB bus.
I want to power the BR camera with a 5volt supply directly on the red cable (disocnnecting it from the USB connector).
Can this be done?
I would alos like to know if there is power on the usb communication cable between the raspberry and the pixhawk. If so, it is redundant relative to the power on the pixhawk servo rail. Again, to decrease power surge on the Pie usb, can I disconnect the power pin in this usb cable?
I would end up having a 3A supply on the camera, 3A supply on the Pi (Br one) and a 3A supply on the Pixhawk rail. Grounded alltogether of course.
No! I answer this one myself. If we disconnect the +5V wire from the usb connector, the communication between the pixhawk and Pie is lost even if +5v is applied on the rail bus. The USB chip in the Pixhawk is probably powered from the usb cable.
It’s probably doable, but if external power is required for the camera or other USB peripherals it might be best to look into an externally powered USB hub.
What kind of supply are you currently using? We recommend using at least a 5V 6A supply to power the 5V electronics. If you’re using only our old 5V 3A supply and are having issues with undervoltage then it’s definitely worth upgrading to one with a higher capacity, and/or adding independent supplies for the components that readily support them.
It’s also important to ensure the main power supply has enough capacity to supply the 5V electronics as well as the thrusters and other components. If the issue persists with a higher capacity supply you may wish to look into limiting thrust to avoid excess instantaneous power consumption - especially on vehicles with several thrusters that get used at the same time.
So it work to power the lowligth cam by hacking the 5v wire and provide a separate power supply. As long as you also provide a common ground between the companion and the camera.
I also solder a 100 uF electrolitic cap on the +5v and ground pin on the camera itself. Smoothing cap to decrease current transient if power supply drop. Would have put a bigger value, but I do not have any handy at the moment.
Going from a 3A to a 6A can probably help. I now have a dedicated 3A for the Pi + Pixhawk and dedicated 3 A for the camera.
One point that Is not solve yet. With this setup I feed my pixhawk with 5V (from the Raspberry) but once inside the pixhawk electronic, it dropped down to 4.6 vcc. My GPS and a ping sonar are connected to the Pixhawk ports and they have 4.6v to play with instead of 5v. Disconnecting these devices did not increase the pixhawk internal voltage. So it’s not related to too much current draw by external instruments. It’s seem to be cause by the pixhawk regulator itself.
Do you guys also mesure 4.6 vcc on your pixhawk HWstate or like me with a DMM right on any +5v pin?
It’s not a problem per se since my instruments do work but it don’t let’s us with a big headroom and thus become more prone to problem in the future.
No problem on this side with my 24 Amp 4S battery pack.
I just measured 5.13 V on my Raspberry Pi power pins, 5.03 V on the Pixhawk’s TELEM and GPS ports, and 5.06 V on the Pixhawk’s DF13 USB port. Our 5V 6A supply is connected to the Raspberry Pi’s power pins and the Pixhawk’s servo rail, and there’s a USB-microUSB cable between the Raspberry Pi and Pixhawk.