ESC Firmware Flashing, Part 2

I actually finished this a while ago, I just haven’t got around to updating the blog since then. A lot has happened since I updated it…so let’s get into it.

In Part 2 of the ESC flashing, I’m going to add a couple pics on the hardware side of things. From there, it should be easy enough to figure out how to do the software yourself, with the link to BLHeli I posted in Part 1.

To start the process, take a knife or razor blade and split the shrink wrap open. Do this on the flat side, which has the heat sink, which will help protect the ESC from the knife. Go slow, and it goes pretty quick.
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Each ESC needs three wires (not four, which I soldered on the first ESC). I cut all the wires I needed for the other three ESCs.
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Here’s all four of the speed controllers, with the wires soldered on.
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The three wires were soldered onto a servo connector, because it was handy, and uses three wires. Any lightweight three pin connector will work fine here, though.
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I then made a jumper to my Arduino with a female servo connector and a four pin row of male header pins.
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This four pin header with only three pins connected allows the ESC to connect to ground and pins 12 and 11 on the Arduino using only one connector. Pins 12 and 11 are default, but can be changed to any Arduino pin. Once connected, I ran a test to make sure the solder joints were good, and then flashed the speed controller.
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Finally, you have to shrink wrap, or otherwise protect the ESCs. I choose to use shrink wrap, it’s easy to use. First, cut the wrap to fit over the speed controller.
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Then, with a lighter or torch, shrink it until it fits nice and snug. Keep the heat moving at all times, don’t stop or you’ll melt a hole in the covering. It doesn’t take long, and soon you’ll be done. Who would even know you’ve ever opened it up?
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That’s all there is too it, besides the software.

P.S. If this seems like too much work, there are several places that sell ESCs already flashed with SimonK firmware, and they are only a couple bucks more then buying them stock.

New Soldering Station/ESC Firmware Flashing, Part 1

I mentioned I was going to get a 300W Weller soldering gun for soldering the power wires, and I did, and it was crap. When I powered it up, the tip started smoking and bubbling. Whatever it was coated in, it was not cleaned below the coating (which appeared to be lead or tin). I could have taken off the coating with a wire brush, but why pay for poor quality? Plus, the whole thing felt cheaply constructed. Instead, I sent it back, and ordered the Hakko FX-888 soldering station I’ve been wanting to get for a while now.

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This is what the tip looked like after heating for a short time. It looked worse with continued heating, turning brown and bubbling more.

My Hakko soldering station is 70W, which should be enough to handle almost anything I care to throw at it. It has a nice heft to it, from the transformer inside, and appears to have excellent build quality. The bottom plate is metal, while the sides and top are plastic. It is adjustable from 200°-480°C (400°-900°F), with an on-off switch and a power LED. The LED is somewhat odd in that it only lights when it is heating the element. This means that it will light for about 25 seconds, which is all the time it takes to heat up (at least to 350°C), and after which will only blink occasionally as it slowly pulses the power to keep the tip hot.

The iron holder is made completely of metal, with a built in brass wool tip cleaner, a rubber lip for wiping the tip, and a sponge, allowing multiple ways or preferences for cleaning the tip.
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The iron is lightweight, yet does not feel cheaply made. The power cord is long enough to cover my entire ESD mat.
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The included tip is a 1.7mm chisel tip. I purchased a 5mm chisel tip along with the iron for better conductivity and thermal mass for soldering heat-sucking materials, such as 12 gauge wire.
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Now, we get to the fun part, something relating to my quad. It’s recommended that you use a custom firmware for your ESC’s on your quad, for a number of reasons. The main one is that the motors will have a quicker response, allowing for a smoother flying quad as the controller can correct an imbalance faster. A close second is that it allows the low voltage cut-off to be disabled. Far better you ruin your Li-Po pack by over discharging it then have your quad crash because the low voltage cut-out shut down a motor on you.

The pads are pretty small and close together. If you’re not comfortable soldering on these pads, you can use a rig that you hold on the pads while flashing instead, however, this is a pain, as further firmware updates will then require you to remove the heat shrink from the ESC again. I decided to go ahead and solder them. I have an Arduino, so that is what I will be using. If you do not, it will be easier for you to get the SiLabs Toolstick for flashing instead of using an Arduino.

I thought I needed all four pads, but it turns out I only need three. I will remove the fourth wire before I shrink wrap the ESC again. The wires will terminated in header pins, for ease of future firmware updates or setting adjustments.

The first step is to tin the pads. This was relatively easy.
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Next, I stripped and bent hookup wire at a 90° angle, tinned it, and soldered it in place by heating it up.
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To get a true feeling of the scale of this soldering job, I’ve placed the tip of a medium point ballpoint pen next to the wires, as well as laid the pen next to the ESC.
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Finally, I hooked it up to my Arduino, and successfully flashed the BlHeli firmware onto the ESC.
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How to flash it with an Arduino, and more on the custom firmware, will be covered in a later post. Also, I have the firmware on the Naze32 flight controller updated. Once all four ESCs are in place, testing on the Naze32 begins, at which point the quad will be getting close to its first test fly…

Status Update

Just a really quick update. I know I’m overdue for one, as I said in my last post I would update the next day or so. I’ve been enjoying the holidays and not having school and haven’t been at my place very much to work on it.

I found the last motor mount, which I couldn’t find, so now the forth motor is sitting so the Loctite on the screws holding the newly attached motor mount and propeller mount can cure. I then attached one propeller to another motor and ran it up, and that thing has some thrust. This quad is going to climb like a rocket when it’s done.

Tonight I have some time available, so I plan to research the custom firmware I’m going to flash on my ESCs, and hopefully tomorrow I will start the process of flashing those. If I don’t break the first one, the other three shouldn’t be too hard.

I need a heavier duty soldering iron for soldering multiple 12 gauge wires. I have ordered a 300W Weller soldering gun for this purpose, which will be here Saturday. At that point, I plan on starting to solder the ESCs to a connector. I had a board to split off the wires, but I realized it’s going to get in the way, so I’ve just going to spider-wire the connectors together. This means the ESCs will all be connected together by solder joints; however, I will keep the bullet connectors between the motors and the ESCs

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Construction Continues

In the last post about my quad construction, I built the basic part of the frame, attaching the arms to the plywood plate that makes up the body of the quad. This post continues from there, as I add the motor mounts to the frame.

For the motor mounts, I went to the craft store where I picked up the wood used to make the frame, and picked up a small sheet of 1/4″ thick basswood. I cut out four small squares from the sheet with a miter saw, each a little bigger then the motor mounts. I then marked the center of each with a line in the middle, and did the same on the arms of the quad.
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I used the lines to line up the wood motor mount plates, then centered the aluminum motor mounts using the lines and eyeballing. I then held it together with finger pressure while I drilled two holes down through the wood plate and the quad arm, using the metal mount as a guide.
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After I drilled the two holes, I marked the arm and the plate with a number and an arrow, so they went back on in the same location, as slight variations while hand drilling can mean a mount drilled on one arm may not fit on another. The holes were then drilled out with a bigger drill bit, to allow an M3 bolt to fit through.
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I then glued the wood plates onto the arms, using the metal motor mount, and two M3 nuts and bolts to clamp it in place for about 30 minutes, then removed the bolts so they didn’t get stuck, and let it dry overnight. In the morning, I put the metal bracket back in, and used it to drill out the other two holes, and a hole in the middle for the motor shaft.
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At this point, I took my motors and used removable blue locktight to mount the mounting accessory kit to my motors. Well, three of them, anyway. I’m not sure where the fourth kit is, right now.
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I know where the mount for the forth motor is, just not the propeller mount, washer, bolt, and the mounting screws.

The mounting plate is mainly held on by the glue, although the bolts do provide a little bit of backup, but the main purpose of the bolts is to hold the motor in place, and allow it to be removed. The nuts are not yet secure, when I balance the motors and props, I will use locktight on the nuts as well. A lose screw or nut could make for a very bad day!
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So this is what it looks now. It’s coming along pretty good, I think. Still quite a lot left to do, though. I plan on having it done before school starts again, though.
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12V, High Current ATX Power Supply Mod, Part 3

I ran some tests using the 12V lead-acid battery I pulled out of my motorcycle for the winter, and I’m only able to charge at a disappointing 1.5 amps, at which point the power supply is down to 10.07V, just above the charger’s low voltage cut-off of 10V. So, I either did something wrong, or I missed something. I’m not sure what I’m going to do about it at this point. At least I can charge though, if just at a very slow rate.

12V, High Current ATX Power Supply Mod, Part 2

This is part 2 of a three part post on turning a PC PSU into a high current, 12V power source for a hobby charger. This was work done on the morning of the 15th, but I did not have time to post about it at that time, so I’m doing it now.

To begin with, I used the following site article as a guide to the conversion. In the article, they put outputs for +5V and +12V, as well as -5V and -12V. However, I really have no need for the other outputs, as I am also building a lab-quality, adjustable, dual output, linear power supply for my miscellaneous projects. So, I simply cut all the other output wires, so that I could add them in the future, if I ever wanted too. Also, there wasn’t a whole lot of room, so I probably would have needed a bigger case if I wanted additional outputs anyway.

What I did in part 1 was cut all the output wires I didn’t need, and solder some banana jack output terminals to the +12V (red terminal) and 0V (black terminal) wires. I had a purple and gray wire, which I was going to use for a “plugged in” indicator and an “power on” indicator, but decided not too, at this time.

If you look, you can see a gold heatsink hidden in the back, this is a 5Ω resistor, which provides a load on the 5V necessary for proper operation of the power supply. I just tucked in it back there because there isn’t a lot of room anywhere else.

I used a drill and a grinder cut a spot for the terminals in the lid, and mounted them in place with some silicon caulk I had handy to help keep them in place, but mainly to keep the mounting nuts from loosening over time. I found a power switch in my junk box and ran a wire from ground (black) to the switch, then from the switch to the green wire. This turns on and off the outputs, but doesn’t shut off the mains power. I then used liquid electrical tape on everything, as there were a bunch of solder joints and lots of cut wires.
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To be double sure, I put a coat of liquid electrical tape on the side of the case next to the wires, as well.
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More modern supplies have voltage sense wires, which are connected at the motherboard connector, to monitor the voltage of the outputs. These are smaller wires of the same color as the wires they monitor, and must be connected together. Mine had them for 3.3V (orange), 5V (red), and I can’t remember now if it had it for 12V (yellow), but I doubt it, as 12V is not critical on a computer. This is the 5V voltage sense wire, connected.
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I put it all together (quite a tight fit now), and measured the output. It looked pretty good, at 12.09V, according to my $5 multimeter.
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Here’s what it looks like, completed.
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Now, I didn’t get a chance to test it much, but the initial results seemed disappointing. I put it on a half amp charge on my three cell Lipo quad pack, and I heard the fan slow down as soon as the charge started. I used the charger’s menu to find out the input (PSU) voltage, and it was around 10.4 volts. Wow, I thought, that’s disappointing, to drop that much under that little of a load. I then tried to up the charge to 6A, which I figured it should be able to handle no sweat, and the charger stopped the charge because the input voltage dropped too much (it can function properly down to 10V). Since it’s rated at 18A, I was honestly very disappointed. I mean, I know the charger won’t be very efficient, as it has to have a buck/boost converter, but even at 50% efficiency, at 12V input it should not have drawn more then 12A input, and I doubt it’s only 50% efficient, I can see 75%, but not 50%. But even then, I should have 18A, right?

Well, I figured I would, but it appears I don’t. I’m not quite sure why. I did think it might be because power supplies sometimes have split rails, and I might have only been pulling from one rail, so I might only have had half the power available. All in all, I’m not quite sure why I don’t have the power I should. I’ll test it more tomorrow, and see just how much current I can charge at before my power supply lets me down.

I’m also going to keep my eye out on a high current, 13.8V power supply on eBay, the ones designed to power radios and other high power electronics that are designed to run off vehicle power. They are generally pretty pricey though. I might be able to make my own, as well. We’ll see.

Testing results will appear in part 3.