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Old May 14, 2012, 07:16 AM
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Open source ESC firmware for F5B

Right, well i thought this would perhaps be a good location to collect data / ideas and so on.

The main concept may change as i go along.

The concept;

Make an open source firmware ESC capable of hardcore F5B abuse. Everyone can decide what firmware to use and modify things as they please. Lower the price of an ESC down to the parts + manufacture. No software provided, no guaranty. Proceed at your own parrel.

1ste phase;

Modify a cheap Chinese 200A controller to accept open source firmware. Probably what has been developed by SimonK for the multicopters or a little something from George Shering. Maybe add a little smoothing / ramp on the throttle input as we go.

http://www.rcgroups.com/forums/showthread.php?t=1513678
http://wiki.openpilot.org/display/Do...g+Instructions

The USBasp programmer
http://www.hobbyking.com/hobbyking/s...dproduct=21321
Red Brick 200A ESC
http://www.hobbyking.com/hobbyking/s...dproduct=18016
Red Brick 200A ESC with BEC
http://www.hobbyking.com/hobbyking/s...dproduct=18017
USB dongle
http://www.hobbyking.com/hobbyking/s...dproduct=10628

2nd phase;

Build our own controller to run with the above firmware. Use the same ATMega8 for the main processor. Upgraded mosfets and smaller form factor power boards. Likely to have a modular connector like the CC controllers. This would allow interaction with other projects from other people.

https://open-bldc.org/wiki/Open-BLDC

3de phase;

Build a new logic board with a better processor. Dependant on what processors become popular with the software writing community in the future.

If you are looking at my blog page, please click ''comments'' to continue reading.
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Old May 14, 2012, 08:03 AM
Needs to do 52 legs !!
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While i am waiting on a USBasp programming lead to hack my Red Brick 200A, i started looking at what componants to use for Phase 2.

The main cost factor seems to be the fets still. Since a CC P180 has 108 fets the cost adds up. To make 10 speed controllers you would need 1080 fets so we can look at the price for 1000 pieces.

The original fets on the P180 seem to be out dated and not available.
http://search.digikey.com/scripts/Dk...KeyWords=4108N

The fets from the ICE 200 seem to be very good and are certainly an option;
http://uk.farnell.com/infineon/bsc01...=BSC019N04NS+G

This looks to be from the same series as the ICE but only rated at 30V like the P180;
http://uk.farnell.com/infineon/bsc01...n-8/dp/1775422

A cheaper alternative that seems better then the P180 fets but less then half the price of the ICE fets;
http://uk.farnell.com/international-...qfn/dp/1782258

A cheaper Infineon with 2.1mohm typical on state resistance vs 1.8mohm of the P180 fets;
http://uk.farnell.com/infineon/bsc02...n-8/dp/1775433

Another option by Fairchild with the lowest on state resistance yet at 0.9mohm (half of the P180);
http://uk.farnell.com/fairchild-semi...77%2B110191386

When having a look around your self, for the selection of the fets it is important to keep an eye on the total rise time and fall time as well as the on state resistance. Longer switching times mean less time spent putting power into the motor and higher resistance.

The white connectors used on the CC controllers to connect the boards;
http://search.digikey.com/us/en/prod...3CT-ND/1015372

Power board side;
http://search.digikey.com/us/en/prod...0CT-ND/1015379

Caps;
http://www.farnell.com/datasheets/50911.pdf

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Old May 14, 2012, 08:31 AM
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Note sure, is this the same processor as on the 200A controllers?

http://uk.farnell.com/atmel/atmega8-...p32/dp/9171371

I read ATMEGA8 16AI 0543 on my Red Brick but can't seem to find that one.

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Old May 14, 2012, 08:49 AM
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Looks like a fun project Joe. Always enjoy seeing what you are up to!

-you have probably seen the interface for the Hydra controller, with respect to throttle curves, but if not, it's worth doing the demo via the Castle link software.

I'd imagine you plan to go beyond that with your own software for an f5b application, allowing the esc to track and or respond to rpm and out put, as the Marcus esc's are supposedly doing.

Look forward to seeing more from Joes Skunk Works.
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Old May 14, 2012, 09:10 AM
Needs to do 52 legs !!
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Hey Eric,

Thanks for dropping by.

The idea would be to test new software stuff on the cheap Chinese controllers first and when they don't burn move to a higher quality product and up the power. Currently there are hardly any controllers around that can take the F5B abuse, never mind ones where we can tweak the software. So provided i can work out the finances, the aim is to change that.

Going by the above source, you are already looking at a price of atleast 50 GBP (75USD) for the fets alone to have something equal to a P180. Then you have to add the PCB and manufacturing. The logic board will require another few small things like gate drivers, linear regulators and so on. So i am guessing the cost for the whole ESC will be around 100 GBP (150USD) up to maybe 150 GBP (225USD). This is where large manufacturers can buy in bulk strait from the source and get cheaper prices. But on the whole it is still acceptable if you ask me.
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Old May 14, 2012, 10:21 AM
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Quote:
Originally Posted by jjmouris View Post
Note sure, is this the same processor as on the 200A controllers?
http://uk.farnell.com/atmel/atmega8-...p32/dp/9171371
I read ATMEGA8 16AI 0543 on my Red Brick but can't seem to find that one.
Yes, this is the good processor. Some have the ATMEGA8L which can workk at low voltage, 3.3V, but only at 8MHz, too slow for us. OK for 16MHz on 5V.The other difference is that some have the mlf package which is very small. If the PCB does not have solder pads leading to teh ISP pins then it is problematic, not insuperable, see your earlier mentioned thread.
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Old May 14, 2012, 10:24 AM
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Originally Posted by jjmouris View Post
The concept;

Make an open source firmware ESC capable of hardcore F5B abuse. Everyone can decide what firmware to use and modify things as they please. Lower the price of an ESC down to the parts + manufacture. No software provided, no guaranty. Proceed at your own parrel.
good idea, no guarantee and at your own peril!

OK at $29, but some may hesitate above 50?
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Old May 14, 2012, 10:54 AM
Needs to do 52 legs !!
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Just a small calculation for fun then.

Given a switching time of 315ns per cycle, then with a PWM rate of 12Khz you would spend 3780000ns every second switching the fets on and off. That is 0.00378 seconds. Multiply that by 2 seconds we spend with the motor on per climb. Still a very very short time. A full flight with 21 seconds of motor at 5000W would see a total of about 0.08 seconds spent switching. Even if you where to dump the whole 5000W strait into heat for those 0.08 seconds then you would still only loose 0.38% worth of Energy. Now take one of those new ICE fets with 67ns per cycle, we gain ?!

Note, the ESC on the other hand has to keep up with this really fast switching or it could run into problems.

Now push 300A through 0.4 mohms (1.6mohm fet on ICE 200) = 0.12V drop, at 300A that makes 36W. Half the fet on state resistance or double the fets and you gain only 18W. Those 18W out of 5000W = 0.36% lost in heat.

Sounds to me as tho we are looking in the wrong places for an improvement. There is likely much more to be gained by running better firmware on the controller and running the whole thing much more efficiently.
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Old May 14, 2012, 11:01 AM
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Originally Posted by epwierman View Post
I'd imagine you plan to go beyond that with your own software for an f5b application, allowing the esc to track and or respond to rpm and out put, as the Marcus esc's are supposedly doing.
Look forward to seeing more from Joes Skunk Works.
That would be one aim. Another would be to use Active freewheeling aka Synchronous Rectification to avoid overheating at part throttle.
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Old May 14, 2012, 11:08 AM
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Originally Posted by jjmouris View Post
Sounds to me as tho we are looking in the wrong places for an improvement. There is likely much more to be gained by running better firmware on the controller and running the whole thing much more efficiently.
You are right. At 6kW like Alan was using in Gommerscheim the ESC must not lose any significant power, especially without heat sink. Otherwise FIRE! the aim is to have the ESC not get too hot. But the ESC can cause losses in the motor if the advance or switching is not correct. So you have to measure motor temparature as well as ESC temperature. All of these things were easy with simple ON/OFF. Full climb ramping is buch more delicate.
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Old May 14, 2012, 11:39 AM
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George, are these the NIKOS P0603BD fets found on my Red Brick?

http://www.unikc.com.cn/UploadFile/p...DDatasheet.pdf

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Old May 14, 2012, 01:32 PM
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http://www.rcgroups.com/forums/showp...5&postcount=58
is the report I gave on mine.

FETs are Niko Semiconductor P0603BD. max 5.8 milliohm at 10V drive. No figure for typical. 30V drain 20V gate. 70A max.
It seems to be the same.
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Old May 16, 2012, 01:02 PM
Needs to do 52 legs !!
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Thanks to George for pointing me to this very interresting read.

http://www.silabs.com/Support%20Docu...Docs/AN208.pdf

By the way, i noticed that the above mentioned typ 0.9mohm Fairchild fets have a much higher gate capacitance then even the old P180 fets. So i think these are probably not a good idea to use despite the tempting low resistance.

Also, the original P180 fets have a forward diode voltage lower then that of the ICE fets. If i am not mistaking, this will lead to higher losses running at partial load in the case of the ICE fets. It's only a small difference 0.85 vs 0.72 but it's worth keeping in mind.

To me the IRFH5301PbF look pretty good for the price.

Joe
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Old May 29, 2012, 02:01 PM
Needs to do 52 legs !!
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Flash the firmware file.
Flashing firmware from file.: C:\Documents and Settings\Jos\Bureaublad\HK200\F5B\F5B1.hex

C:\Documents and Settings\Jos\Bureaublad\HK200\kkmulticopterflashto ol_0.62\lib\avrdude\windows\avrdude.exe -C C:\Documents and Settings\Jos\Bureaublad\HK200\kkmulticopterflashto ol_0.62\lib\avrdude\windows\avrdude.conf -p m8 -P usb -c usbasp -B 8 -e -U flash:w:C:\Documents and Settings\Jos\Bureaublad\HK200\F5B\F5B1.hex:i

avrdude.exe: set SCK frequency to 93750 Hz
avrdude.exe: warning: cannot set sck period. please check for usbasp firmware update.
avrdude.exe: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.02s

avrdude.exe: Device signature = 0x1e9307
avrdude.exe: erasing chip
avrdude.exe: set SCK frequency to 93750 Hz
avrdude.exe: warning: cannot set sck period. please check for usbasp firmware update.
avrdude.exe: reading input file "C:\Documents and Settings\Jos\Bureaublad\HK200\F5B\F5B1.hex"
avrdude.exe: writing flash (3700 bytes):

Writing | ################################################## | 100% 2.55s

avrdude.exe: 3700 bytes of flash written
avrdude.exe: verifying flash memory against C:\Documents and Settings\Jos\Bureaublad\HK200\F5B\F5B1.hex:
avrdude.exe: load data flash data from input file C:\Documents and Settings\Jos\Bureaublad\HK200\F5B\F5B1.hex:
avrdude.exe: input file C:\Documents and Settings\Jos\Bureaublad\HK200\F5B\F5B1.hex contains 3700 bytes
avrdude.exe: reading on-chip flash data:

Reading | ################################################## | 100% 2.31s

avrdude.exe: verifying ...
avrdude.exe: 3700 bytes of flash verified

avrdude.exe done. Thank you.
1ste one done !!!
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Old May 30, 2012, 12:03 PM
Needs to do 52 legs !!
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This is a small 4 pole 4200KV inrunner with no load on 2S Lipo.

Except for the slight hickup on the last burst it seemed to be working fine.

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