> For the complete documentation index, see [llms.txt](https://nxp.gitbook.io/hovergames/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://nxp.gitbook.io/hovergames/rddrone-fmuk66/connectors/rc-input.md).

# RC input

RDDRONE-FMUK66 Rev. C has a single RC input connector. It has PPM/SBUS, RSSI and Spektrum inputs, and a RC output that together with the PPM/SBUS input forms a UART TX/RX pair.

RDDRONE-FMUK66 Rev. B and older revisions had two connectors for input from the radio controller. The FRSKY port supports PPM and SBUS inputs and has telemetry output for an FrSky radio controller. The other connector, labelled RSSI/PPM, supports PPM, SBUS and Spektrum radio protocols. This port also has an RSSI input. FrSky telemetry is impossible when the PPM/SBUS input on either connector is also used. 

{% embed url="<https://oscarliang.com/pwm-ppm-sbus-dsm2-dsmx-sumd-difference/>" %}

{% embed url="<https://oscarliang.com/what-rssi-transmitter-receiver-quadcopter/>" %}

## RDDRONE-FMUK66 Rev. C RC input connector pinout

| Pin | Signal           | Voltage |
| --- | ---------------- | ------- |
| 1   | VCC              | +5.0V   |
| 2   | RC IN (PPM/SBUS) | +3.3V   |
| 3   | RSSI IN          | +3.3V   |
| 4   | SPEKTRUM IN      | +3.3V   |
| 5   | RC OUT           | +3.3V   |
| 6   | GND              | GND     |

## RDDRONE-FMUK66 Rev. C schematic

![](/files/-LVs3ECD9BO5uj8It3qX)

## RDDRONE-FMUK66 Rev. B FRSKY connector pinout

{% hint style="danger" %}
Rev. B (and older boards) are **not supported** anymore. This information is left for reference.
{% endhint %}

| Pin | Signal           | Voltage |
| --- | ---------------- | ------- |
| 1   | VCC              | +5.0V   |
| 2   | RC OUT (TELEM)   | +3.3V   |
| 3   | RC IN (PPM/SBUS) | +3.3V   |
| 4   | GND              | GND     |

## RDDRONE-FMUK66 Rev. B FRSKY RC IN/RSSI connector pinout

| Pin | Signal           | Voltage |
| --- | ---------------- | ------- |
| 1   | VCC              | +5.0V   |
| 2   | RC IN (PPM/SBUS) | +3.3V   |
| 3   | RSSI IN          | +3.3V   |
| 4   | SPEKTRUM IN      | +3.3V   |
| 5   | GND              | GND     |

## RDDRONE-FMUK66 Rev. B schematic

![](/files/-LOrv09vENHlBkUgGCL6)


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://nxp.gitbook.io/hovergames/rddrone-fmuk66/connectors/rc-input.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.