# Mixer from SDcard

**URL:** <https://discuss.px4.io/t/mixer-from-sdcard/12555>\
**Category:** PX4 Autopilot\
**Created:** [August 20, 2019, 10:02pm UTC](https://discuss.px4.io/t/mixer-from-sdcard/12555 "2019-08-20T22:02:34Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![Jontan](https://discuss.px4.io/user_avatar/discuss.px4.io/jontan/32/4481_2.png) [@Jontan](https://discuss.px4.io/u/Jontan)\
**Post date:** [August 20, 2019, 10:02pm UTC](https://discuss.px4.io/t/mixer-from-sdcard/12555/1 "2019-08-20T22:02:34Z")

</div>

Can you help me?

Hi, I would like to try my mixer file (cyclic.txt). It is very simple but I have not been able to make it work in my pixracer.

* * *

```
#quadrotor X
R: 4x 10000 10000 10000 0

# left servo
M: 2
S: 1 0 -5000 -5000 0 -10000 10000
S: 1 1 5000 5000 0 -10000 10000

# right servo
M: 2
S: 1 0 -5000 -5000 0 -10000 10000
S: 1 1 -5000 -5000 0 -10000 10000

```

* * *

is installed in microsd/etc/mixers/cyclic.txt

I have also tried to include a config.txt file with the following information

* * *

```
MIXER cyclic set
set PWM_AUX_OUT 12
set PWM_AUX_DISARMED 1500
set PWM_AUX_MIN 1000
set PWM_AUX_MAX 2000
set PWM_AUX_RATE 50

```

* * *

---

<div class="post-metadata">

**Author:** ![JulianOes](https://discuss.px4.io/user_avatar/discuss.px4.io/julianoes/32/30_2.png) [@JulianOes](https://discuss.px4.io/u/JulianOes)\
**Post date:** [August 21, 2019, 9:34am UTC](https://discuss.px4.io/t/mixer-from-sdcard/12555/2 "2019-08-21T09:34:22Z")

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What instructions are you following?

---

<div class="post-metadata">

**Author:** ![Jontan](https://discuss.px4.io/user_avatar/discuss.px4.io/jontan/32/4481_2.png) [@Jontan](https://discuss.px4.io/u/Jontan)\
**Post date:** [August 21, 2019, 4:53pm UTC](https://discuss.px4.io/t/mixer-from-sdcard/12555/3 "2019-08-21T16:53:36Z")

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Hi, I followed these instructions

[https://dev.px4.io/v1.9.0/en/concept/system\_startup.html](https://dev.px4.io/v1.9.0/en/concept/system_startup.html)

And at the end the bootlog.txt file is created in the SD  
root with the following message

ERROR [init] Failed loading mixer: /etc/mixers/cyclic.main.mix

---

<div class="post-metadata">

**Author:** ![JulianOes](https://discuss.px4.io/user_avatar/discuss.px4.io/julianoes/32/30_2.png) [@JulianOes](https://discuss.px4.io/u/JulianOes)\
**Post date:** [August 22, 2019, 9:26am UTC](https://discuss.px4.io/t/mixer-from-sdcard/12555/4 "2019-08-22T09:26:01Z")

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Ok, it looks like it looks for the mixer file in the wrong location.

I can see that only replacing a mixer file using the same name is supported:  
[https://dev.px4.io/v1.9.0/en/concept/system\_startup.html#starting-a-custom-mixer](https://dev.px4.io/v1.9.0/en/concept/system_startup.html#starting-a-custom-mixer)

What airframe have you selected?

---

<div class="post-metadata">

**Author:** ![Jontan](https://discuss.px4.io/user_avatar/discuss.px4.io/jontan/32/4481_2.png) [@Jontan](https://discuss.px4.io/u/Jontan)\
**Post date:** [August 22, 2019, 4:10pm UTC](https://discuss.px4.io/t/mixer-from-sdcard/12555/5 "2019-08-22T16:10:39Z")

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Hi JulianOes

I am using an X4 quadrotor, my intention is to add two servos that functions as the elevons of a delta wing that works with attitude control.

I have a question, only .txt files are placed on the sd card, right?

---

<div class="post-metadata">

**Author:** ![JulianOes](https://discuss.px4.io/user_avatar/discuss.px4.io/julianoes/32/30_2.png) [@JulianOes](https://discuss.px4.io/u/JulianOes)\
**Post date:** [August 23, 2019, 9:50am UTC](https://discuss.px4.io/t/mixer-from-sdcard/12555/6 "2019-08-23T09:50:00Z")

</div>

According to [https://dev.px4.io/v1.9.0/en/concept/system\_startup.html#starting-a-custom-mixer](https://dev.px4.io/v1.9.0/en/concept/system_startup.html#starting-a-custom-mixer) you can replace the mixer file but it needs to have the same filename as the one that is chosen by the airframe.

An alternative is to just build the firmware yourself and add a new airframe with the mixer file that you need.