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Old Oct 12, 2011, 08:43 AM
RC beginner
New York
Joined Oct 2008
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Quote:
Originally Posted by timecop View Post
Maybe our bldc expert dave1993 has some ideas?
far too many for my own good...

m8 has rep for mysterious resets. it usually turns out to be firmware bug but assuming code is ok maybe:

take special care on the reset pin. pu, caps, and tying to vcc make things worse sometimes. if possible connect NOTHING. even half inch run will pickup nearby fast edges. i went so far as to cut off the pin (make sure your optiboot is working good).

reverse biased io will do it too. make sure no pulses on io pins above vcc or below gnd. even sub-ns glitches will cause latchup and trigger bod.
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Old Oct 12, 2011, 09:02 AM
RC beginner
New York
Joined Oct 2008
6,054 Posts
hearing the word "expert", regardless of intent, thrills me. considering 3 yrs ago i thought ESC was the mechanism for ejecting toy pilot from the model.

seriously!
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Old Oct 12, 2011, 09:48 AM
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Joined Dec 2010
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Quote:
Originally Posted by dave1993 View Post
i think a lot of blowouts with these flashed units are due to improper or no overcurrent sensing. a stalled prop may kill a modded esc where those with stock firmware survive. theres little margin between false shutdowns and blown fets. lots of fine tuning required here maybe.
There is no current sensing in (this) branch of firmware.

Quote:
m8 has rep for mysterious resets. it usually turns out to be firmware bug but assuming code is ok
Code should be OK. there's only one way to get 3tone reset , and its definitely not that. Pretty sure its not brownout either. I did look at vcc and set a trigger on falling and etc, but did not see anything happening.

Next thing is that *stock* firmware works fine, so there's definitely something missing
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Old Oct 12, 2011, 01:48 PM
flying beam
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through the Looking Glass
Joined Apr 2008
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Bought some of these : http://www.hobbyking.com/hobbyking/s...ontroller.html

Thinking they would easy to flash, same as Mystery 12A they say (I don't own any of those btw).

Unfortunately no programing pads

Will have to use some pogo pins (more time waiting...).

Do the Mystery ones have programing pads ?

Thank you.
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Old Oct 12, 2011, 02:39 PM
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Madrid, Spain
Joined Mar 2006
763 Posts
do you guys see an improvement on flight behaviour with the new firmware?

I bet yes, but just want to see some real life experiences...
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Old Oct 12, 2011, 06:25 PM
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One would think, these ESC manufactures would get the message. Hmmm.
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Old Oct 12, 2011, 09:15 PM
If it flies, I will crash it
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USA, CO, Westminster
Joined Jan 2008
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We are starting to see some sign's since some motor manufacturers are starting to build motors specifically designed to work with multicopters.

Another interesting thing I have noticed. Of 3 ESC's on my Tri the rear one is getting quit hot during flight. I don't feel that it is a huge problem, it isn't dangerously hot but I do find it interesting that one is getting hot while the other two show no heating at all. I may try moving the ESC's around or I may wait. I have two more on the way.

Rob...
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Old Oct 12, 2011, 09:17 PM
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Just curious, do you know if the Timing is all set the same on all the ESCs?
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Old Oct 12, 2011, 09:23 PM
If it flies, I will crash it
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USA, CO, Westminster
Joined Jan 2008
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These are flashed. I did not notice if the problem existed or not before flashing. I just know it does now. I feel that it is a hardware quirk. That is why I ordered replacements. I will try those and see if it is still there.

I considered BEC heating but I am actually powering the board with the left front ESC. It stays cool. Another consideration is the motor on that arm. I have "Tailed it in" a few times so it is possible that the motor on the rear is the culprit. Hum, more things to look over.

Rob...
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Old Oct 12, 2011, 11:47 PM
hacker
Canada, BC, North Vancouver
Joined Dec 2010
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Quote:
Originally Posted by dave1993 View Post
i collected dozens of different versions of bernards code (i2c, rs232, pwm, inv/noninv, fast/slow, fat/thin, dark/light... ). permutations were endless. including when he started putting rc calibration bytes in ee. dont know if those variations are still on his site or deleted. i lost interest when he switched to m88.
I'm hoping this tree can grow to support all atmega8 variants without having to change the core. The 48/88 isn't really a huge difference, so maybe that, too, if any are in production. I'd rather focus on existing boards since at least then people can easily try this tree and/or improve something they already have.

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Originally Posted by dave1993 View Post
i agree it was not perfect but he deserves HUGE credit for pioneering the whole esc mod craze. til then most idiots were trying (key word: trying) to build from scratch. and theres his generosity with source and support.
The only reason we're talking about this is because quax DID start from scratch and made his code open, then eventually notice it could be easily ported to other boards being shipped, which he then did. Who knows how much his work actually influenced other manufacturers since he released it in 2003/2004.

Quote:
Originally Posted by dave1993 View Post
i made a couple attempts at understanding his code but lack of patience and language barrier frustrated me. only after davidt adapted and improved the comments did i see the light (HARDWARE light... still dont like poking around software... specially asm... yuccchhh!). and even he was standing on the shoulders of konze.
I started hacking on the code just because I was unhappy with a few things (8kHz PWM, dodgy startup, etc.), and wanted to make it better. I started by ripping out absolutely everything not needed to make it work, plus some. I was surprised at how hard it was to break. I've now since added most of the things back after learning why quax originally added them. Other changes are mostly micro-optimizations, particularly to the PWM and RC interrupts.

Quote:
Originally Posted by dave1993 View Post
not sure about (this) program but quaxs were very fussy about hardware. using bottom fet on resistance for current sensing instead of resistor make these el cheapo controllers very sensitive to fet part numbers.

i think a lot of blowouts with these flashed units are due to improper or no overcurrent sensing. a stalled prop may kill a modded esc where those with stock firmware survive. theres little margin between false shutdowns and blown fets. lots of fine tuning required here maybe.

bemf timing is tricky too IMO and very dependent on fet numbers and batch.

bottom line: escs are the kwaziest people...
quax' original at90s2313 builds did have current sense, but I have yet to find an atmega8 port that still has any. The code is often still there but nothing is checked. Everything I've seen still relies on timing to limit duty cycle and in turn limit current because of the assumed voltage difference between RMS drive voltage and back-EMF at the sensed timing. AVR Turnigy Plush and quax' original tree both still have problems where they think the motor is still running when you forcibly stop the motor very quickly -- Plush is actually worse -- but they don't tend to fry in this state, even though the timing loss typically spirals up to maximum speed. I think this is because the commutation switching ends up acting like a 33% duty cycle limit by itself.

Current sense by Rds[on] of a FET, really? Do you have any reference for this? It would be possible, I guess, but I'm not sure what would be used for the other side of the comparator in this case. It would be good to resurrect this if it does exist.

It seems that almost nobody ships ESCs that have a direct input to output PWM without some averaging or maximum change limiting; even quax' original tree has this. My fork here has this all removed other than the two power range limits by timing which are also in quax' trees, but make an assumption about input voltage and motor kv to be effective. I have yet to be able to fry anything with this, but perhaps I am not trying hard enough. All of the FET frying that I did do was a while ago when I was first working on this tree, and seemed to happen at weird times like when splashing into puddles, not when landing upsidedown at full throttle, which I did try a few times.
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Old Oct 13, 2011, 03:40 AM
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Quote:
Originally Posted by Nek View Post
Their older versions were the same. Plush could be a newer version that does not use an Atmega8. If your 2 plush have an Atmega8 then the RCT 10A are most likely the same.

In a couple days I will flash my RCT 18A and see how it goes...

tigar, there is a newer tgy.hex compiled by simon a few days ago. I will most likely try this one on one of the 18A to see how it goes. I am also using the old tgy.hex in my RCT 30A and they work great!
Did you flash your RCTimer 18A ESCs successfully? I'm going to try this for the first time tonight.
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Old Oct 13, 2011, 04:53 AM
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France
Joined Nov 2003
281 Posts
tests

Hi SimonK,
nice work you did ! Thanks for having shared this with us.
I tried the last version (16Khz) in flight on an Hexa H and a quadri. The motors now run very smoothly (AXI or aerodrive). Motors can now start at very low RPM, they are less noisy (power range set to 900). It reduces also woobles compared to previous converter version.

I tried also the Ultra PWM with a new version of Flyboard I2C converter. Compared to Fast PWM, it reduces even more wooble (as I feel it).

Next step is to try even quicker pulse, like max pulse = 512 usec. Start high during 100 usec period, then the duty between 0 and 512 usec, or even stronger between 0 and 256.
I assume it needs to change the code a bit for that, the duty has to be divided by 2 somewhere to have full power range (currently 900). Do you have any hint for this ?
Thanks
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Old Oct 13, 2011, 06:13 AM
RC beginner
New York
Joined Oct 2008
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Quote:
Originally Posted by simonk View Post
The 48/88 isn't really a huge difference, so maybe that, too, if any are in production. I'd rather focus on existing boards
actually except for pinout the m88 family is radically different. far more hardware features. 2x more pwm is of particular interest to us. also incompatible from binary standpoint due to completely new io and ram map. c/ardu guys may not notice because these details are hidden from them.

i agree about staying with m8 controllers due to availability (The Chip That Wouldn't Die!!). i've seen a few 8051 boards but personally not run into an m88 yet.

Quote:
Originally Posted by simonk View Post
The only reason we're talking about this is because quax DID start from scratch
i was under the impression his flea was based on a previous homegrown design. i had copies of a schematic and source but dont recall the fellows name or if he was still alive. not sure because it was couple years ago. in any case quax spoke english and was still around.

Quote:
Originally Posted by simonk View Post
Current sense by Rds[on] of a FET, really? Do you have any reference for this? It would be possible, I guess, but I'm not sure what would be used for the other side of the comparator in this case.
IIRC there were a few attempts in one of the huge DIY threads. again. it was a long time ago. has to be the same comparator circuit as bemf?

i have a few stolen images (some from ref design kits and couple inhouse leaks) and two of them i was told had protection via Ron. one was emax variant. i was directed to two particular bytes that set limits and sure enough it did change the stall shutdown point. it seemed too small to be bemf timeout. did not have source and never really got into the software end myself so cant say for sure.

it would be the only way to do current sense since there is no resistor in the cheapies.

Quote:
Originally Posted by simonk View Post
All of the FET frying that I did do was a while ago when I was first working on this tree, and seemed to happen at weird times like when splashing into puddles, not when landing upsidedown at full throttle, which I did try a few times.
i notice this too. my only two burnouts occurred when esc got soaked landing in wet grass (i only fly pre-dawn). never during a crash. rx also get wet and quit. drying in the sun always brings them back though.

BTW thanks for putting so much effort into this project. i intend to give it a try when i get a chance.
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Old Oct 13, 2011, 10:33 AM
Registered User
Ironbridge (UK)
Joined Jan 2009
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Hi,

what did you set your start and end points to when you tried the ultra pwm and what update rate did you use?

thanks

Josh


Quote:
Originally Posted by obor View Post
Hi SimonK,
nice work you did ! Thanks for having shared this with us.
I tried the last version (16Khz) in flight on an Hexa H and a quadri. The motors now run very smoothly (AXI or aerodrive). Motors can now start at very low RPM, they are less noisy (power range set to 900). It reduces also woobles compared to previous converter version.

I tried also the Ultra PWM with a new version of Flyboard I2C converter. Compared to Fast PWM, it reduces even more wooble (as I feel it).

Next step is to try even quicker pulse, like max pulse = 512 usec. Start high during 100 usec period, then the duty between 0 and 512 usec, or even stronger between 0 and 256.
I assume it needs to change the code a bit for that, the duty has to be divided by 2 somewhere to have full power range (currently 900). Do you have any hint for this ?
Thanks
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Old Oct 13, 2011, 01:10 PM
Droner
SebastianJ's Avatar
Denmark, Capital Region of Denmark, CPH
Joined Mar 2006
2,410 Posts
I found a possible candidate for the custom FW:

Mystery red 10A ESC

Mystery red 20A ESC

Atmel brains and programming pads.

They come in many sizes from 10A to 120A

Someone should give them a try, not me - I've spent all my allowance.
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