# Connectors

{% hint style="info" %}
When running the FMU you will see the RGB-LED glow, follow the link bellow to know what the different meanings for each color are.

<https://docs.px4.io/main/en/getting_started/led_meanings.html>&#x20;
{% endhint %}

There are two relevant versions of the FMUK66. The Rev. C/D and the Rev. E/F. Each version has a slight difference, the main difference to be seen is the number of PWM pins. Below are images of the location of all pins on both boards. &#x20;

### Rev C/D:

* Front side of the board:

<figure><img src="https://3991116448-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-M8v3AGPa-j5DtYx8zqd%2Fuploads%2FDCjkpnaGRL7FFKTseteU%2Fimage.png?alt=media&#x26;token=188835c2-06eb-47a8-81bf-d01941d3c58a" alt=""><figcaption></figcaption></figure>

* Back side of the board:

<figure><img src="https://3991116448-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-M8v3AGPa-j5DtYx8zqd%2Fuploads%2F7ydCeUcswmBlaugG28hP%2Fimage.png?alt=media&#x26;token=27009ea4-50a2-4ab4-9de9-f5358f6f6b94" alt=""><figcaption></figcaption></figure>

* Location and description of the PWM pins:

<figure><img src="https://3991116448-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-M8v3AGPa-j5DtYx8zqd%2Fuploads%2FPx9Cviwd7gGCQyb9PLeK%2Fimage.png?alt=media&#x26;token=4ea73f62-afc4-4852-b39f-8ee51c556864" alt=""><figcaption></figcaption></figure>

### Rev E/F:

* Front side of the board:

<figure><img src="https://3991116448-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-M8v3AGPa-j5DtYx8zqd%2Fuploads%2FQiLxHGobYfRpjUlT4of0%2Fimage.png?alt=media&#x26;token=4ce20418-cba9-401a-9856-bd3e0104eddf" alt=""><figcaption></figcaption></figure>

* The back side of the board:

<figure><img src="https://3991116448-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-M8v3AGPa-j5DtYx8zqd%2Fuploads%2F1Q58AFRbilrnJe6qIYJp%2Fimage.png?alt=media&#x26;token=274f7ce7-9c70-4276-9779-2837d9a2a501" alt=""><figcaption></figcaption></figure>

* Location and description of the PWM pins:

<figure><img src="https://3991116448-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-M8v3AGPa-j5DtYx8zqd%2Fuploads%2FLajR3Ttv6vtAKDhNIJlz%2Fimage.png?alt=media&#x26;token=09ff3989-121f-4772-94e5-728b36f120d8" alt=""><figcaption></figcaption></figure>