# Mixer & PWM Update rate problem

**URL:** <https://discuss.px4.io/t/mixer-pwm-update-rate-problem/2643>\
**Category:** Uncategorized\
**Created:** [March 6, 2017, 11:39am UTC](https://discuss.px4.io/t/mixer-pwm-update-rate-problem/2643 "2017-03-06T11:39:57Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![muealexi](https://discuss.px4.io/letter_avatar_proxy/v4/letter/m/f07891/32.png) [@muealexi](https://discuss.px4.io/u/muealexi)\
**Post date:** [March 6, 2017, 11:39am UTC](https://discuss.px4.io/t/mixer-pwm-update-rate-problem/2643/1 "2017-03-06T11:39:57Z")

</div>

I am working on a new drone project and need to create a mixer with 12 feed through outputs, so I created a vol.main.mix and a vol.aux.mix file with 6 outputs each. I also changed the rcS and interface code to call them up, but doing this I have received some error messages, but not sure why.

[boot] Fault Log is Armed

sercon: Registering CDC/ACM serial driver  
sercon: Successfully registered the CDC/ACM serial driver  
[i] microSD mounted: /fs/microsd  
[hardfault\_log] Fault Log is Armed

WARN [param] selected parameter default file /fs/mtd\_params  
rgbled on I2C bus 2 at 0x55 (bus: 100 KHz, max: 100 KHz)  
MS5611\_SPI on SPI bus 4 at 2 (20000 KHz)  
WARN [ms5611] no device on bus 4  
MS5611\_SPI on SPI bus 1 at 3 (20000 KHz)  
WARN [bst] no devices found  
INFO [ver] match: PX4FMU\_V2  
WARN [hmc5883] no device on bus 1 (type: 2)  
WARN [lis3mdl] no device on bus 2  
WARN [hmc5883] no device on bus 2 (type: 1)  
WARN [mpu6000] no device on bus 5  
WARN [mpu9250] no device on bus 4  
MPU6000 on SPI bus 1 at 4 (1000 KHz)  
WARN [mpu6000] no device on bus 5  
WARN [mpu9250] no device on bus 3  
WARN [mpu9250] no device on bus 4  
L3GD20 on SPI bus 1 at 1 (11000 KHz)  
LSM303D on SPI bus 1 at 2 (11000 KHz)  
ERROR [meas\_airspeed] no MS4525 airspeed sensor connected  
ERROR [ets\_airspeed] no ETS airspeed sensor connected  
ERROR [ets\_airspeed] no ETS airspeed sensor connected  
INFO [load\_mon] stack check enabled  
WARN [param] Error: Parameter UAVCAN\_ENABLE not found.  
INFO [px4io] default PWM output device  
INFO [mavlink] mode: Normal, data rate: 1200 B/s on /dev/ttyS1 @ 57600B  
INFO [mavlink] mode: OSD, data rate: 1000 B/s on /dev/ttyS2 @ 57600B  
WARN [param] Error: Parameter UAVCAN\_ENABLE not found.  
INFO [ver] match: PX4FMU\_V2  
px4flow [137:100]  
WARN [px4flow] scanning I2C buses for device…  
INFO [mavlink] mode: Config, data rate: 800000 B/s on /dev/ttyACM0 @ 57600B  
Mixer should exist  
INFO [init] Mixer: /etc/mixers/voliro.main.mix on /dev/pwm\_output0  
**ERROR [pwm] PWM\_SERVO\_SET\_SELECT\_UPDATE\_RATE**  
Aux Mixer should be loaded here:  
INFO [init] Mixer: /etc/mixers/voliro.aux.mix on /dev/pwm\_output1

NuttShell (NSH)  
nsh\> \0x1b[KINFO [lib\_\_ecl] EKF aligned, (pressure height, IMU buf: 21, OBS buf: 16)  
WARN [commander] Not ready to fly: Sensors not set up correctly

The error that bugs me the most is the one about the update rate, because I checked and the variable PWM\_RATE is 400, but it still gives out this error. A reason for this to happen might be that I commented out the SYS\_AUTOSTART feature, because it always set the variables with wrong information.

I also thought about using the IO\_pass mixer, since that one is already a passthrough mixer, but I am not sure how to access 12 different outputs. I need 6 outputs for motors and 6 for servos.

I would be happy if anybody might now a elegant why to do this. I think my approach creating all new mixers might be to complicated for the easy mixer I need.