# 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: 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:

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

The question should be specific, self-contained, and written in natural language.
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.