remembering that the
signal wire is orange
on this ESC (Figure
Now, connect the
battery to the setup
to power the ESC.
Then, plug in the USB
programmer to your
machine. A USB
extension cable makes
this plugging and
unplugging a lot
easier. In the
KKFlash Tool, set the
programmer to Afro
from the dropdown
menu. Make sure that
the COM port setting
is correct and that the
“use defaults” check
box is checked. Our
ESC is based on an
select the atmega 8-
(8kb flash) option from the controller menu. Set the
firmware repository to Afro NFET and select the most
recent version of the firmware (Figure 12).
Finally, click the green image of a running person
and let the program Flash and verify. When completed,
the status should read “Flashing of firmware was
Remember earlier when I espoused the merits of
working from a current-limited power supply? It was not
without reason! On my first attempt at Flashing SimonK
onto the ESC, I heard a bang, saw a flash, then watched
error messages scroll across the KKFlash Tool terminal. I
immediately removed power, but the ESC was nonresponsive in later attempts to Flash it.
After ordering another ESC, I did a post-mortem. It
turns out that the motor connectors — while disconnected
— were still close enough that an arc jumped between two
of them. I cut away the plastic shrink tube enclosing the
ESC and saw a small black piece of encapsulant fall out.
That’s never a good sign.
I flipped the board over and saw that there was a hole
blown out of one of the NFETs (Figure 13). A current-limited supply would likely have prevented this from
happening. After this incident, I taped the motor
connections down in a spread configuration (Figure 14)
and never had another issue.
After Flashing the newest SimonK firmware, I repeated
my earlier tests with the same setup and videoed it
( https://youtu.be/Z_HyZ3CUZXw). The motor sounded
roughly the same, and had a minimum/maximum RPM of
3,200 and 12,500 (very similar to the stock configuration).
The biggest difference I noticed was on the step test from
full stop to full throttle.
The motor’s torque actually rotated my test plate on
the bench (see 11 seconds into the video). This tells me
that the accelerations achieved by this firmware are much
greater than the stock configuration. For an aerial
photography platform, this probably isn’t good, but for a
racing setup it would be a decent performance gain. I
didn’t see any issues with/during the calibration procedure;
the biggest downfall of this install was the questionable
SERVO 07.2017 55
Figure 15: Finding the ESC in the BLHeli PDF just takes a little
searching. This is a nice reference to have as it allows you to identify
cloned ESCs and Flash them with the proper firmware.
Figure 14: To prevent the arcing, I taped the output leads down in a
spread configuration and placed the motor’s connectors under the
Figure 13: My first attempts at
Flashing new firmware ended with
an arc jumping between the output
connectors and completely
destroying one of the NFETS,
blowing a hole in the casing!