Building my first tricopter and everything is working great except the yaw servo. The first two servos never worked, and then finally tried an analog Mystery S0403 and got yaw movement though with lots of twitching as soon as the battery is plugged in and during testing. Refresh rate is set 50hz. Later tried a few other servos and they instantly burnt up, one when not even moving. Now thinking the first two burnt as well but didn't see it. I want to go buy some more metal gear servos, but a little scared they are just going to be instantly ruined. Any thoughts? Settings?
Multiwii Pro board
Multistar 2213-980 motors
Afro 20 Amp ESCs
Tricopter Yaw Servo Twitches and Burns up
Re: Tricopter Yaw Servo Twitches and Burns up
IF you keep burning servos that could be based on either
- servos are junk (some cheapo servos are just that); or
- the attached mechanical load is too high; or
- voltage is not correct; or
- pwm rate is too high - this happens regularly when attaching servo (50Hz for analog servos up to 333Hz for digital heli tail servos) to motor output (490Hz).
- or loads of other reasons
- servos are junk (some cheapo servos are just that); or
- the attached mechanical load is too high; or
- voltage is not correct; or
- pwm rate is too high - this happens regularly when attaching servo (50Hz for analog servos up to 333Hz for digital heli tail servos) to motor output (490Hz).
- or loads of other reasons
Re: Tricopter Yaw Servo Twitches and Burns up
Thank you Hamburger. I went and bought a new digital metal gear servo last night, but any specific settings I should check or adjust before doing so? I know the burnt servos weren't the best, but they had all been used on other projects and worked great. Leads me to fallow your advice of load, voltage, or pwm but could use a little insight as to what I should be looking for. Learning quickly, but still a ways to go.
Re: Tricopter Yaw Servo Twitches and Burns up
You mentioned you have a "pro"board. I assume that means it has 2560 atmega chip.
Then in MWii config.h, verify you have hardware pwm enabled and set the rate to nothing higher than what your servo can handle (best to keep a safety margin; you most likely will not notice the difference in flying).
Simple mistake is to attach servo to motor output - then twitch&burn.
If you have no way to check for the pwm value and frequency, then alternate way is as follows:
attach servo horn and use servo tester or direct connect to rx to find the center position. Next, hook up servo to mwii board output. If servo horn moves to and stays at very different position, then it most likely sees a motor output min value and will burn soon. Disconnect! Find documentation with hardware pwm pin mapping for mega2560 boards.
Then in MWii config.h, verify you have hardware pwm enabled and set the rate to nothing higher than what your servo can handle (best to keep a safety margin; you most likely will not notice the difference in flying).
Simple mistake is to attach servo to motor output - then twitch&burn.
If you have no way to check for the pwm value and frequency, then alternate way is as follows:
attach servo horn and use servo tester or direct connect to rx to find the center position. Next, hook up servo to mwii board output. If servo horn moves to and stays at very different position, then it most likely sees a motor output min value and will burn soon. Disconnect! Find documentation with hardware pwm pin mapping for mega2560 boards.
Re: Tricopter Yaw Servo Twitches and Burns up
The output doesn't seem to be a motor output so that's good. Though of all the servos I've tried only one works, a Mystery S0403 Analog though it still has a lot of jitters. (and is too small to use anyways for the Tri) All other servos are unresponsive or previously burnt.
These are my parameters, and are correct to best of my knowledge, but verification would be great if possible.
/**************************************************************************************/
/*********************** motor, servo and other presets ***********************/
/**************************************************************************************/
/* motors will not spin when the throttle command is in low position
this is an alternative method to stop immediately the motors */
#define MOTOR_STOP
/* some radios have not a neutral point centered on 1500. can be changed here */
#define MIDRC 1500
/*********************** Servo Refreshrates ***********************/
/* Default 50Hz Servo refresh rate*/
#define SERVO_RFR_50HZ
/* up to 160Hz servo refreshrate .. works with the most analog servos*/
//#define SERVO_RFR_160HZ
/* up to 300Hz refreshrate it is as fast as possible (100-300Hz depending on the cound of used servos and the servos state).
for use with digital servos
dont use it with analog servos! thay may get damage. (some will work but be careful) */
//#define SERVO_RFR_300HZ
/*********************** HW PWM Servos ***********************/
/* HW PWM Servo outputs for Arduino Mega.. moves:
Pitch = pin 44
Roll = pin 45
CamTrig = pin 46
SERVO4 = pin 11 (aileron left for fixed wing or TRI YAW SERVO)
SERVO5 = pin 12 (aileron right for fixed wing)
SERVO6 = pin 6 (rudder for fixed wing)
SERVO7 = pin 7 (elevator for fixed wing)
SERVO8 = pin 8 (motor for fixed wing) */
//#define MEGA_HW_PWM_SERVOS
/* HW PWM Servo outputs for 32u4 NanoWii, MicroWii etc. - works with either the variable SERVO_RFR_RATE or
* one of the 3 fixed servo.refresh.rates *
* Tested only for heli_120, i.e. 1 motor + 4 servos, moves..
* motor[0] = motor = pin 6
* servo[3] = nick servo = pin 11
* servo[4] = left servo = pin 10
* servo[5] = yaw servo = pin 5
* servo[6] = right servo= pin 9
*/
//#define A32U4_4_HW_PWM_SERVOS
#define SERVO_RFR_RATE 50 // In Hz, you can set it from 20 to 400Hz, used only in HW PWM mode for mega and 32u4
//#define SERVO_PIN5_RFR_RATE 200 // separate yaw pwm rate.
// In Hz, you can set it from 20 to 400Hz, used only in HW PWM mode for 32u4
These are my parameters, and are correct to best of my knowledge, but verification would be great if possible.
/**************************************************************************************/
/*********************** motor, servo and other presets ***********************/
/**************************************************************************************/
/* motors will not spin when the throttle command is in low position
this is an alternative method to stop immediately the motors */
#define MOTOR_STOP
/* some radios have not a neutral point centered on 1500. can be changed here */
#define MIDRC 1500
/*********************** Servo Refreshrates ***********************/
/* Default 50Hz Servo refresh rate*/
#define SERVO_RFR_50HZ
/* up to 160Hz servo refreshrate .. works with the most analog servos*/
//#define SERVO_RFR_160HZ
/* up to 300Hz refreshrate it is as fast as possible (100-300Hz depending on the cound of used servos and the servos state).
for use with digital servos
dont use it with analog servos! thay may get damage. (some will work but be careful) */
//#define SERVO_RFR_300HZ
/*********************** HW PWM Servos ***********************/
/* HW PWM Servo outputs for Arduino Mega.. moves:
Pitch = pin 44
Roll = pin 45
CamTrig = pin 46
SERVO4 = pin 11 (aileron left for fixed wing or TRI YAW SERVO)
SERVO5 = pin 12 (aileron right for fixed wing)
SERVO6 = pin 6 (rudder for fixed wing)
SERVO7 = pin 7 (elevator for fixed wing)
SERVO8 = pin 8 (motor for fixed wing) */
//#define MEGA_HW_PWM_SERVOS
/* HW PWM Servo outputs for 32u4 NanoWii, MicroWii etc. - works with either the variable SERVO_RFR_RATE or
* one of the 3 fixed servo.refresh.rates *
* Tested only for heli_120, i.e. 1 motor + 4 servos, moves..
* motor[0] = motor = pin 6
* servo[3] = nick servo = pin 11
* servo[4] = left servo = pin 10
* servo[5] = yaw servo = pin 5
* servo[6] = right servo= pin 9
*/
//#define A32U4_4_HW_PWM_SERVOS
#define SERVO_RFR_RATE 50 // In Hz, you can set it from 20 to 400Hz, used only in HW PWM mode for mega and 32u4
//#define SERVO_PIN5_RFR_RATE 200 // separate yaw pwm rate.
// In Hz, you can set it from 20 to 400Hz, used only in HW PWM mode for 32u4
Re: Tricopter Yaw Servo Twitches and Burns up
I also have a very similar problem. I am using the NanoWii (atmega 32u4) I tried it with two different high quality digital MG servos and both had the same problem. The symptoms are:
Right after I plug in the battery the servo goes crazy and eventually heats up. I can move the servo with my fingers and it doesn't respond to control inputs. Twitching is slower on 50 and 160Hz, than 300Hz.
However if I power the board first through a USB cable and plug in the battery after the FC has initialized everything works fine.
I tried to power the board and the servo different ways, but this makes no difference. I also tried using 2.3 and now the new 2.4, but no change. I have tried everything I could think about.
Could this be a software bug? Maybe this issue could be resolved by using hardware PWM. Anyone knows how to enable this for the servo?
Right after I plug in the battery the servo goes crazy and eventually heats up. I can move the servo with my fingers and it doesn't respond to control inputs. Twitching is slower on 50 and 160Hz, than 300Hz.
However if I power the board first through a USB cable and plug in the battery after the FC has initialized everything works fine.
I tried to power the board and the servo different ways, but this makes no difference. I also tried using 2.3 and now the new 2.4, but no change. I have tried everything I could think about.
Could this be a software bug? Maybe this issue could be resolved by using hardware PWM. Anyone knows how to enable this for the servo?