Thanks Steve
Gimbal Bay | 3DR Solo Development Guide
====================================================================
Power Supply
The Gimbal Cable supplies two different voltage sources to the Gimbal Bay:
- VCC 5V (4.75V to 5.4V).
- VCC Battery (12V to 16.8 V).
VCC 5V should be used to power the camera (only). The camera must not draw more than 1A.
NOTE : The VCC 5V supply is also used as the backup supply for the Pixhawk. While the current is not limited, if more than 1A is used the vehicle may fail when running on backup power.
Solo Gimbal Cable
The
Solo Gimbal cable terminates in a
Molex 5031490800 (
alt link) connector. A gimbal board is connected using the corresponding
Molex 5031540890 (
alt link) connector.
Pin Name Color Description
1 VCC Battery Red 12V to 16.8V. Max recommended current/power is ~3A/50W. Drawing additional current may damage the battery and increases the risk of accident.
2 VCC 5V Yellow 4.75V to 5.4V voltage pin for Camera (only). Current should be less than 1A.
3 GND (Gimbal) Black
4 GND (USB) Brown
5 Gimbal Rx White
6 Gimbal Tx Green
7 USB D+ Blue Positive differential data signal to iMX6 OTG USB port.
8 USB D- Violet Negative differential data signal to iMX6 OTG USB port.
=================+++++=====================
I am not familiar with messing around at GoPro rear expansion port/BUS, for power injection.
If from USB as in charging and power injection into the camera, I am familiar.
If Pixhawk also uses this VCC 5V, and a GoPro is not allowed to drain more than 1A, I suggest never fly with empty battery or non fully charged battery.
I never measured Hero4 power consumption using milliamps meter, like I did with Black3 original using dummy battery, but 77 minutes is the best non stop 4K/25FPS protune ( no LCD BacPac, no Wifi ) I can get with original battery which I already recycled well like 10 discharge/recharge cylce.
H4 battery is claimed to be 4.4 watt hours at 1160 mAh 3.8V, as per sticker on battery.
If I can get 77 minutes, that means my Black4 is draining 903mAh at 3.8V. Its very close to 1A.
The problem is, if the gimbal can power the camera and at the same time charging the battery, power will exceed 1 amp. Hence its a must to fly with fully charged battery.
Here my worry of exceeding 1A is not purely Black4 heat damage. I worry the power backup for Pixhawk get disturbed and if bad luck comes upon us, its double bad luck
The only time I understood power injection to GoPro rear expansion port/BUS is when using the GoPro Battery BacPac. Its not power injection per se, its power usage allocation. When Battery BaPac is used, GoPro takes power first from Battery BP and when at approx 20% level, power usage is shifted to camera battery. So its never about charging.
I never like any gimbal to inject power to my GoPro, as no fly time of any hobby drone battery today can exceed 0.5 hour anyway and I do not like the heat issue when charging + supplying power to camera.
I think in earlier days, DJI Zenmuse gimbal also often overheat Black3 due to its capability of Zenmuse gimbal to charge a GoPro. Those days Zenmuse gimbal has the rear expansion port/BUS connector on gimbal, like Solo's. Later model Zenmuse gimbal do not use GoPro rear expansion port anymore and use the USB instead. GoPro and DJI love affair ended anyway and DJI drones can never have controls of GP cams the way Solo can.
Back to P2P theory of over voltage.
" I wonder if something in the FW (error, typo, etc) is causing the Solo's computer to send higher than spec voltage to the power input pins on the GoPro?"
This could also be the reason too.
In the earlier days of Black3 original, GoPro camera does not like unstable voltage condition coming from USB. It can freeze the camera. I think above 5.3volts, problem starts. Not all powerbanks are issues free when it comes to powering a GoPro for long recording. This also could explain why some members here are having freezing issues with the GoPro or some commands not working..... if voltage injected by Solo's gimbal to the camera is not within GP "liking"

.