The leds share ground with the motor, but that doesn't necessarily mean that the signal inputs do also. Ideally the signals would first pass through optical isolators, but that doesn't mean they do.
dual battery mod
- Thread starter gtomko
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The leds share ground with the motor, but that doesn't necessarily mean that the signal inputs do also. Ideally the signals would first pass through optical isolators, but that doesn't mean they do.
Just poked around in a spare motor pod. Powered it from a bench supply at 14V. All 3 LEDs came on green. the atmegaA8A is powered by an LTC 5V regulator on the pod. So no wonder 3DR had problems. The PixHawk2.0 uses 3.3V signalling for the PWM outputs. looking at the A8A datasheet, when powered from 5V, the input threshold is 2.6V for a 1 and 2.2 for a 0 (page 332/3) While this might work ok in a non flight critical noise free application IMHO they were asking for trouble in the Solo.
It might be worth some testing, but after realizing (I should have checked that a long time ago!) that there was a mismatch in the signalling the real solution is the PixHawk 2.1 Green.
This is a design fault, a mistake that a recent EE grad would be raked over the coals for in any of the companies I've worked for.
3DR should have rolled out the proposed update to the PixHawk2.0 to all the production Solos.
Grumble grumble grumble...
It might be worth some testing, but after realizing (I should have checked that a long time ago!) that there was a mismatch in the signalling the real solution is the PixHawk 2.1 Green.
This is a design fault, a mistake that a recent EE grad would be raked over the coals for in any of the companies I've worked for.
3DR should have rolled out the proposed update to the PixHawk2.0 to all the production Solos.
Grumble grumble grumble...
I did a quick test on the motor pod, and the third signal line from the left, when looking into the jack on the motor pod with the propeller up, is directly connected to the main motor ground.
There should be an opto at that point that would both isolate the signals and match logic levels.
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Ya this is why the engineers that were overridden by management are so disgruntled about it. They all said this is bad. They all said it needs different ESCs. But the executive management decided the flaw was cheaper.
Any clue as to what the SiteScan Solo's are fitted with, I've heard rumblings that there was a new ESC, but I have no ground truth.
Solo is still a great platform, it still may be worth testing with the ESC's rewired and the CPU & Pixhawk powered by a different battery.
You have direct experience with the fault happening in flight, could you produce a description of how to make it happen?
Solo is still a great platform, it still may be worth testing with the ESC's rewired and the CPU & Pixhawk powered by a different battery.
You have direct experience with the fault happening in flight, could you produce a description of how to make it happen?
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As far as I know, the motor pods are no different. And the firmware with the slew rate limiting is still there in site scan.
Ok, good info.
As far as I can tell 3DR is still using Arducopter 1.5.? so it would make sense that they have not changed the ESC/MotorPod citcuitry or gone to their own version of the PixHawk2.1 (Green).
Wow, you don't get crap for 12K these days... ;>))
As far as I can tell 3DR is still using Arducopter 1.5.? so it would make sense that they have not changed the ESC/MotorPod citcuitry or gone to their own version of the PixHawk2.1 (Green).
Wow, you don't get crap for 12K these days... ;>))
If you are you referring to the gps failures and controller signal losses without the second battery, the first solo I had was not too bad, and only lost gps randomly every other flight or so. This new replacement I have loses either gps lock or controller signal every 10 or so minutes of flight. No need to do anything special to reproduce the failures, just hover for a little while.
With the second battery powering the computers and radios I haven't had a single failure after hours of flight.
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Sorry gtomko, that was directed to P2P. He experienced an in flight motor stall that is directly attributed to the PWM "ground bounce" issue. It seems hard if not impossible to reproduce on the ground, I was wondering if he could describe the events leading up to the motor stall. and if there were any logs to evaluate.
Didn't mean to hijack your thread, but your work with the dual battery has shown that there is a lot of noise introduced into all sorts of places by the less than stellar design of the Solo main board and power distribution system.
Apologies...
Apologies...
I've personally been wondering if a couple filter caps placed judiciously might not help things.
The trouble is that the noise we are dealing with is pretty powerful. The transistors switching on and off the motor coils create serious voltage spikes. It may be possible to get things down to an acceptable level with enough tantalum and ferrite, but it's never going to get you close to the stability of a second battery.
After a couple more hours of flight testing on the dual battery mod, the gps performance has been spectacular. During flight with clear view of the sky, the solo maintains between 12 and 14 satellites occasionally dropping to 10. In between and under trees where it would struggle to maintain 6 for a lock, I haven't seen it drop below 8.
The solo has not lost gps lock once since the mod, and the controller connection has also been perfectly reliable. I doubt there would be an appreciable difference in the range of the controller link, but I will do some long range tests at some point just to check.
I have a 1ah lipo on the way, when it arrives I'll post some pics and a simple set of instructions for getting it all set up. I definitely would not recommend attempting this modification if you aren't comfortable with a soldering iron or losing the warranty, but if your solo continuously experiences many random errors, it might be worth a try.
The solo has not lost gps lock once since the mod, and the controller connection has also been perfectly reliable. I doubt there would be an appreciable difference in the range of the controller link, but I will do some long range tests at some point just to check.
I have a 1ah lipo on the way, when it arrives I'll post some pics and a simple set of instructions for getting it all set up. I definitely would not recommend attempting this modification if you aren't comfortable with a soldering iron or losing the warranty, but if your solo continuously experiences many random errors, it might be worth a try.
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I'm really impressed this has had such a dramatic effect. Is bigger or additional ferrite beads something that can be done to mitigate the issue without rewiring the whole thing?
From my experience, if you want a computer to run consistently you need clean power. If you have many computers, all communicating with each other, and you are trusting them with such a critical task as the flight controller on a uav, you need extremely clean power.
It may be possible with enough ferrite and tantalum to get some solos to be reliable most of the time. Adding the second battery wasn't a big deal, I just cut and soldered a few wires. The whole mod took about 30 minutes. You could probably spend countless hours chasing your tail to find what part is susceptible to what noise under what conditions. Or you could run the sensitive electronics on clean power and have fun flying a reliable drone.
It may be possible with enough ferrite and tantalum to get some solos to be reliable most of the time. Adding the second battery wasn't a big deal, I just cut and soldered a few wires. The whole mod took about 30 minutes. You could probably spend countless hours chasing your tail to find what part is susceptible to what noise under what conditions. Or you could run the sensitive electronics on clean power and have fun flying a reliable drone.
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