Music City Multi-Rotor Club
(January 26th 2012 meeting topic)
Re-Flashing your ESCs for optimal multi-rotor copter use - a How-to guide.

This month’s MCMR topic is “How to flash your AVR based ESCs to provide better motor reaction for multi-rotor usage”. This modification is termed as “Rapid Drive” technology on the newer, 32-bit based ESCs coming to market later this year. What the modified firmware does is a) Removes the portions of the original ESC firmware that is not used in multi-rotor applications, and (more importantly) b) Increases the reaction time between the ESC and the motor. This provides superior copter control and will enhance your performance in level holding and stability by using your existing Amtel AVR unit you have today. Furthermore, some of today’s latest flight control boards (such as the recently released ‘Naza’ will not work without these high-reaction-time ESC’s.

However, there are some caveats, first - only ESCs that are based on the Amtel Mega8 processor will work. This includes most of the older units and a much smaller set of today’s units. The newer “Turnigy Plush” (and other HobbyWing clone/compatible) series have changed to a SIL processor and no modified code is available yet. The good news is that the current crops of Hobby King “Blue Series”, Mystery (brand) series, RCTimer, older Turnigy Plush series, HobbyWing, ZTW, and our own Hobby-Lobby eRC units are great candidates for modification.
To make a connection to your ESC requires removing the factory heat shrink tubing, soldering programming wires or using a programming pad, or very small clip leads from your programmer to the ESC. We will demonstrate how to make a programming pad out of Insta-Morph available on, and also how to flash the modified firmware onto an ESC.

There are six leads that need to be connected between your AVR programmer and your ESC: VCC, GND, MOSI, MISO, SCK and RESET. Some of the ESCs have PADs that are lined up and are easier to attach, some have PADs scattered around the board and some have nothing. The exact ESC you have will determine how to attach to your AVR programmer. Alternatively, by using a programming pad created with Insta-Morph, or by using micro-pin hooks, one can re-flash without having to heat up a soldering iron!

Once you have the ESC connected to the AVR programmer, you can run the FlashTool and program the ESC. After flashing, test the ESC before re-covering it with new heat shrink tubing.

The latest version of the modified firmware by SimonK includes a throttle calibration feature that will need to be set before testing. Connect your modified ESC to your R/C receiver’s throttle channel. You do not want the RX powered at this point. Power up your Radio (TX), and set the throttle on your TX to full. Next, provide power to your flashed ESC using a Lipo battery. Your RX will now be powered up from the ESC. Listen for the beeps. It will start by beeping three times indicating that a 3-cell battery is connected, then it will give an extra –beeep—indicating that it has ‘learned’ the throttle’s “High” position. Within a second or two of hearing the –beeep--, bring your throttle stick on your TX to minimum and listen for the beep, beep. You are now calibrated and ready to install onto your QUAD… Once you finish the other three ESC modifications. ?

The main RCGroups thread is here:
** Download the ESC flashing tool at
*** For a AVR programmer, I used the SparkFun Pocket AVR Programmer, available here:
1” heat shrink tubing, available locally at Bluff City Electronics on ElmHill Ave.
Insta-Morph available here: ... B003QKLJKQ