Change motor pin

[KW272]

Hi,

I build my quad with the Hobbyking ATmega 2560 V2.0 Controller. But my PWM output for motor 4 is broken.
I tried to change the output to anpther pin, but I couldnt figure it out how to do it.

Does someone know how to change the motor pins on MultiWii 2.3?

[QuadBow]

Does someone know how to change the motor pins on MultiWii 2.3?

Yes, I do.
However, it requires significant changes in the file output.cpp, and therefore, is not that simple.
Furthermore, it limits your expansion possibilities (e.g. shifting to a hex or octo configuration).
In case you can claim for warranty, do so and get a new board.
In case you have broken the pin-out yourself, provide the information of your configuration:
- copter type
- motor pins still available
- servos required

[KW272]

Hi QuadBow, thank you for your reply.

I can not return the board therefore I would be very pleased, if you help me to change the code.

I have a QUADX. The broken pin is pin 6, (for the 4th motor).
I dont need any servos.

[waltr]

What is broken? the physical connector pin? or the Atmega output?
Is just the connector pin then it may be best to replace the connector.
If the Atmega output is bad then changing the code is the only way to fix it.
I have never tried this so do not know how its done. I think I've seen other threads here about this.

[KW272]

No its the ATmega output. I have read the threads about changing the motor pins, but they are for older Multiwii versions. It does not work with multiwii 2.3

[QuadBow]

The broken pin is pin 6, (for the 4th motor).

OK, pin 6 is related to motor number 2 due to the programming schema.
I show you how to hijack the pin 7, which can't be used without confusion any more for a hex or an octo.

Look for the following code in the file output.cpp:

Code: Select all

     #if (NUMBER_MOTOR > 2)
      #ifndef EXT_MOTOR_RANGE 
        OCR4A = motor[2]<<3; //  pin 6
      #else
        OCR4A = ((motor[2]<<4) - 16000);
      #endif
    #endif

and replace it by:

Code: Select all

      #if (NUMBER_MOTOR > 2)
      #ifndef EXT_MOTOR_RANGE 
        OCR4B = motor[2]<<3; //  pin 7
      #else
        OCR4B = ((motor[2]<<4) - 16000);
      #endif
    #endif

Furthermore, you have to swap the pin assignment as follows:

Code: Select all

#if defined(MEGA)
  uint8_t PWM_PIN[8] = {3,5,7,2,6,8,9,10};      //for a quad+: rear,right,left,front   //+ for y6: 7:under right  8:under left
#endif

And the initialisation shown below

Code: Select all

    #if (NUMBER_MOTOR > 2)
      // init 16bit timer 4
      TCCR4A |= (1<<WGM41); // phase correct mode
      TCCR4A &= ~(1<<WGM40);
      TCCR4B |= (1<<WGM43);
      TCCR4B &= ~(1<<CS41); // no prescaler
      ICR4   |= 0x3FFF; // TOP to 16383;    
      TCCR4A |= _BV(COM4A1); // connect pin 6 to timer 4 channel A
    #endif

has to be changed to:

Code: Select all

    #if (NUMBER_MOTOR > 2)
      // init 16bit timer 4
      TCCR4A |= (1<<WGM41); // phase correct mode
      TCCR4A &= ~(1<<WGM40);
      TCCR4B |= (1<<WGM43);
      TCCR4B &= ~(1<<CS41); // no prescaler
      ICR4   |= 0x3FFF; // TOP to 16383;    
      TCCR4A |= _BV(COM4B1); // connect pin 7 to timer 4 channel B
    #endif

That should it be. I hope I have not forgotten anything.
But, I have only derived it from the code, I have not tested it.
So, I do not guarantee anything. All changes you adapt are at your own risk.
Have much success!

[KW272]

I changed the code, but still the same problem, just at pin 7.

I think the timer is broken. pin 6 and 7 are both connected to timer 4. I tried to connect pin 6 to timer 5. but now my motor starts and stops really quick.

Timer 2 (pin 9 and 10) is an 8 bit timer.

How can i change the timer of pin 6?

[Hamburger]

You cannot.
Configure a hex and use your private mixing with avoiding the motor[x] which relates to broken pin.
If you cannot figure that out buy new board

[shikra]

^^ neat idea..

[mathieu974]

Hey guys
Ive the same problem, my pin 6 seems to be dead (crius aiop)...
Is there a software solution because i would like to use my board in a tricopter and i should have a yaw servo pin allocation...
Does the hexa solution work for a quad?
What is the "private mixing"?

Note : i have 2.2volts at each pin but 4.2volts at the pin 6...


Thx a lot

[haydent]

You cannot.
Configure a hex and use your private mixing with avoiding the motor[x] which relates to broken pin.
If you cannot figure that out buy new board

this works easy enough

concept is, enable copter type that has more motors, then specify layout file so extra available motors have same values as broken pin/s

http://www.multiwii.com/wiki/index.php? ... ual_Mixing

have a look at output.cpp to find layouts default mix

[IamTheVector]

this is the correct answer. Worked for me :

viewtopic.php?f=16&t=1681&p=66138#p66138

No "extra pin enabled" or other strange methods .