Converting TowerPro 25A type 2 ESC's from PWM to TWI/I2C control - Page 3 - RC Groups
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Nov 03, 2007, 01:42 PM
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Try and lead the TWI/I2C cabe between the voltage regulators before heatshrinking. Also be careful not to melt the servo wires during the heatshrinking. Well applied heatshrink will help keep the little pad baord firmly in place.
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Nov 03, 2007, 01:44 PM
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The final result. As a nice little touch I-ve pulled the original stickers off of the old heatshrink and stuck them back on the modified ESC, which is now a TowerPro 25A MAG8i ESC for m1. And it has passed the Quality Check, i.e. it has been shown to work correctly.
Nov 03, 2007, 01:46 PM
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Final words
Of course QC could also as easilly been taken to read “Quax Conform”. Without the great work of Quax and several other quadrotor geniuses, we would not see the rapid development of these systems that we have seen in the last year or so.
Of course neither those who developed the firmware and figured out the changes needed to the PCB, nor the author of this manual can accept any liability for your errors or for failure of the ESC. And you probably voided your warranty by modifying it. However, if all went well you should hopefully enjoy many good and safely powered flights with this TWI/I2C enabled ESC.
Nov 03, 2007, 02:16 PM
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PS: Someone came up with an alternative name and label for these converted controlers:
Nov 03, 2007, 02:26 PM
I don't want to "Switch Now"
pmackenzie's Avatar
Thanks for posting this. Lots of cool information.
The schematics and hex files are for the 17 and 18 amp TP controllers.
I assume that everything (other than perhaps the FETs) is the same in the 18 and 25?

Pat MacKenzie
Nov 03, 2007, 04:27 PM
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The diagrams are roughly the same for the 17A type 1, 25A type 1 and 25A type 2.

If I understand it correctly there is a 18A type 1 or 2 which has the FETs inverted. That's the reason for the clear warning to make sure you use the correct firmware for the ESC you are modifying. (see post 165 here:

Looking at price, imho the 25A is the best buy: more than enough power for most applications at about the same price as the 17 and 18A. So why go for less

Originally Posted by pmackenzie
Thanks for posting this. Lots of cool information.
The schematics and hex files are for the 17 and 18 amp TP controllers.
I assume that everything (other than perhaps the FETs) is the same in the 18 and 25?

Pat MacKenzie
Nov 04, 2007, 02:25 AM
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Hi Arthur
Great work. I just ordered the ESC from U\H. I want to dedicate it only to the MK system so I will remove the voltage regulator and also I will solder pin plug row for better connection (no solder) BTW When I remove the voltage regulator there is special thing that I have to do?

Have a nice weekend
Nov 04, 2007, 03:24 AM
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The ESC has a separate 5V supply on the main PCB. So no problem removing the BEC circuit PCB. But you will loose the ability to supplant the 5V on the flight controler. That supply is limited to 1A. If you run multiple servos off of that (e.g. for camera stabilisation), you may eventually overload that. Of course U/H also have nice separate BECs which can supply up to 4A and can run off of 2-6 S lipos ;=))
Nov 04, 2007, 03:07 PM
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Two additional tips:

a) A simple sewing pin is a must have tool for the conversion. It's an excellent instrument to carefully remove small solder bridges between two pins, or to pry in between pins if in doubt about solder bridges.

b) If using the ISP on the SerCon you need the following wires from the 10 strand flat-cable (normally red wire should be 1):

2) 5V
3) (TXD, not used for the ISP)
4) (PPM, not used for the ISP)
5) RST
6) (INT0, not used for the ISP)
7) SCK
8) (RXD, not used for the ISP)
10) GND
Nov 05, 2007, 05:26 PM
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Just finished wiring up 4 more TowerPro 25A type W (=2) ESCs. And here's another tip:

For the wires which need to be connected to the processor legs, after removing the insulation of the end of the wire, cut it back to 0.5 to 1 mm, then bend the bare wire 70-90 degrees at the point were the insulation ends, keeping the rest of the wire reasonably straight at this time. This allows you to press it more firmly against the processor leg while soldering and it avoids the insulation becoming loose due to the pressure of a bend. Once securily soldered to the processor leg you can bend it whichever way is best (just don't go back and forth repeatedly, unless you're in the mood for breaking wires and having to redo them )
Nov 10, 2007, 04:03 AM
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Just noticed that still offer wirewrap wire (30G). Haven't been able to find that over here lately. Have found that some old modem cables had thin wires which might be usable for conversion even if thicker than wirewrap wire.
Nov 19, 2007, 05:30 PM
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TowerPro 50A ESCs can also be covnerted

I had ordered two 50A TowerPro ESCs and sent one to Quax to see whether those could also be converted to TWI / I2C. His first info back says yes. So I-ll start another thread on converting those. See:
Last edited by Arthur P.; Nov 19, 2007 at 05:40 PM.
Nov 24, 2007, 03:15 PM
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In the MK forum in the BL controler conversion thread there is a bit of a discussion ongoing on creating a programming adapter for ATMega8 SMD chips. That would avoid quite some soldering to those thin little legs. I had already done a first attempt with condom latex and simple epoxy, but without casing the pressure isn't high enough, and curing time too long, to get a good mold. Today I found some interesting new material at the creative hobbies shop. A sort of plastic clay which does not require 30 min baking in the oven to cure, just 5-10minutes in a mikrowave. Just to give it a try I pressed about 1 cm3 of this stuff over the processor on a Holger Esc for 5 seconds, baked it in the microwave for 5 minutes, and already have a resultant mold which fits snuggly over the CPU. Now this was a quick and dirty try and thus there is some creasing of the clay. But even this first cap could probably be used to drill some thin holes from the correct pin inpressions up, and glue some wire-wrap wire in such a way that the SCK, MISO, MOSI, 5V and GND pins are correctly connected by just pressing the cap firmly down over the processor with a small clamp. That would shave about an hour of the TowerPro 25A ESC conversion in my estimation and reduce the number of wires left in place to only the SDA, SCL and GND wires for the TWI interface.

I won't have time the rest of this weekend to progress this, but I have a good feeling about this stuff

In addition to this use, this stuff weighs near to nothing, and can be painted, could be quite useful for creating complex shapes in RC models.
Dec 12, 2007, 03:23 AM
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TowerPro 25A type 2 ESCs require new firmware

Just got a little note from Bernard (Quax) about the TowerPro 25A ESCs. Due to a different FET than the old version, at 11.1V with current firmware they tend to overheat. He is working on new firmware which should solve the problem. For those flying with them current software, keep an eye on the ESC temps, and have a bit of patience. I-ll post a link as soon as the new firmware is out.

Further details here:
Dec 12, 2007, 11:04 AM
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quax's Avatar
Originally Posted by Arthur P.
Due to a different FET than the old version, at 11.1V with current firmware they tend to overheat.
The versions with TPC8114's as P-FETs have that problem for sure. Those with TPC8111's as P-FETs may work without any problem.

Is someone out there, who has the TPC8111's on his board and can test it?


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