What's this mystery multicopter board coming from HobbyKing?

Jonas Beseler May 16, 2012 at 11:43pm

Char of flitetest mentioned it in his Director Video as a KK2 Board

John Arne Birkeland May 13, 2012 at 8:21am

But the processor core and hence math performance is exactly the same for a 328/2560, so we run into the same computational limitations when trying to make sense of the sensor data and calculate an AHRS solution. The performance gain from extra PWM hardware is marginal in this regard.

Vernon Barry May 12, 2012 at 2:46pm

R_Lefebvre, No you got it backwards. The 328 on APM sums the PPM inputs into a format the Mega 2560 take tak ein in on one channel instead of reading 8channels with 8 pins thus limiting free resources on the 2560. Then, we smartly use the hardware timers within the 2560 which make PWM functions out for 8 or more channels of outputs to drive servos or speed controls. To say the 328 and 2560 have the same "power" is some serious over simplification. Bascially, they allow us to use the same IDE and more or less the same code base, but when we get into hardware performance, it's apples and oranges. See the chart below about PWM outs. 6 PWM outs on a 328P isn't going to cut it for an Octo.

Arduino board models

Processor	Frequency	Voltage	Flash kB	EEPROM kB	SRAM kB	Digital I/O pins	...with PWM	Analog input pins
ATmega1280	16 MHz	5 V	128	4	8	54	14	16
ATmega2560	16 MHz	5 V	256	4	8	54	14	16
ATmega328P	16 MHz	5 V	32	1	2	14	6	6

Rob_Lefebvre May 12, 2012 at 1:24pm

Which we then do through a 328 anyway... ;)

Developer

John Arne Birkeland May 12, 2012 at 12:57pm

@Lefebvre: Yes, that pretty much sums it up. The only thing that might make a difference is that the 1280/2560 has more hardware PWM channels, making it easier to drive servos/motors.