Reprogramming of a low
cost 6a BLC (e.g. Turnigy 6A)
This BLC has my favorite MPU, an ATmega8 on board and therefore it was possible to adapt my brushless software to it.
There exists a PPM version, a UART version and a I2C version.
People told me, that it works ;-)
The schematic: 6a schematic
The PPM version with sources: 6a ppm-r08
The UART version with sources: 6a uart-r06
I2C schematic: 6a i2c
The I2C version with sources: 6a i2c-r09
For the I2C version two ports of the AVR have to be rewired. The I2C schematic is also in the ZIP.
Brushed to Brushless Conversion:
A very simple brushed to brushless conversion can be done by using the brushed motor PWM as an input for a BLC. I realized that methode for X-UFO conversion to brushless years ago and actually with success for walkera 4#3 brushless conversion. The use of a simple port-int is not recommended, better is the use of an input capture register, like the ICP of the ATmega8 series.
The Turnigy-6A needs a little change on the PCB to support ICP as an input. You have to exchange Pin12 and Pin32 of the ATmega8 on the board. Here is an image from TheSteve with an example how to do it. But pay attention, you need some skills to do it.
If you do the exchange, you can use the following sources for the Turnigy-6A with ICP-input.