As I started to build my eBay HF450 quad-copter, I decided to tear into the ESCs and this is what I found.
First they are labeled as Hobbypower SimonK 30A 2-4s lipo with 5V/2A BEC. They did have a boot loader installed but when I attempted to flash via the signal wire the flash failed part way thru. I then proceeded to open them up and found they do have programming pads which are labeled. I then learned the hard way that this ESC does not have an external oscillator, luckily I was able to use my Arduino board as an oscillator and recovered the chip. Since I was playing with the fuses I notice that the defaults (originally) had not been set to Simon's recommendation, I took care of that on each one. Even after updating to latest firmware, the signal wire flash connects but fails part way thru. I ended up flashing "tgy".
Interesting point of note, identical item is for sell on amazon and advertised as having an external oscillator.
I am curious if there would be any benefit in adding an external oscillator such as this one http://www.digikey.com/product-detail/en/CSTLS16M0X53-A0/490-5999-1-ND/3845199
or is it not worth the hassle.
Replies
Also, here is the original firmware from this ESC
esc orginal.hex
The only benefit would be that the oscillator speed would drift less with temperature.
The oscillators in the Atmega8 and similar parts aren't all that great, and slow down significantly with temperature. This means that the pulse lengths appear to be shorter as the ESC heats up, which means that it may not reach full power without a significant calibration margin (overlap). Usually the only noticed problem is on the other end -- if the arming pulse is too close to starting the motor, it may think the pulse is too high to be in the idle range when the ESC is really cold (like when starting in very cold weather), and not arm unless you first warm up the ESC. Otherwise, you may not notice too much of a difference.
It might be fun actually getting it on there, though, and ceramic resonators can be somewhat moisture and impact sensitive.
Simon, do you think the lack of an external osillator could be cuasing issues with flashing via the signal wire?