> For the complete documentation index, see [llms.txt](https://nxp.gitbook.io/mr-canhubk344/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/mr-canhubk344/hardware/connectors-and-user-i-o/uarts.md).

# UARTs

## Location of UART connectors

The MR-CANHUBK3 contains 4 UART connectors (P2, P5, P24, P25)

<figure><img src="/files/fcBkiiRnsIlEUglNJfFt" alt=""><figcaption></figcaption></figure>

## UART Connectors

P2 and P5 follow the Dronecode 6-pin UART standard. Pin 1 is able to supply limited 5V power to an external device such as a GPS module or sensor.

**Connectors P2 and P4:**

<table><thead><tr><th width="114.33333333333331">Pin #</th><th width="171">Signal</th><th>Specification</th></tr></thead><tbody><tr><td>1</td><td>5V</td><td>(Optional) Limited 5V Output</td></tr><tr><td>2</td><td>TX</td><td>3.3V</td></tr><tr><td>3</td><td>RX</td><td>3.3V</td></tr><tr><td>4</td><td>CTS</td><td>3.3V</td></tr><tr><td>5</td><td>RTS</td><td>3.3V</td></tr><tr><td>6</td><td>GND</td><td>0V (GND)</td></tr></tbody></table>

Connectors P24 and P25 are also 6-pin JST-GH. However, they are not fully compliant with the Dronecode standard since pins 4 and 5 are repurposed to be a second UART channel instead of the handshaking lines RTS/CTS. The pinouts are shown below.

**Connector P24 (UART9/10):**

<table><thead><tr><th width="129.33333333333331">Pin #</th><th>Signal</th><th>Specification</th></tr></thead><tbody><tr><td>1</td><td>5V</td><td>Limited 5V Output (Optional)</td></tr><tr><td>2</td><td>TX (UART9)</td><td>3.3V</td></tr><tr><td>3</td><td>RX (UART9)</td><td>3.3V</td></tr><tr><td>4</td><td>TX (UART10)</td><td>3.3V</td></tr><tr><td>5</td><td>RX (UART10)</td><td>3.3V</td></tr><tr><td>6</td><td>GND</td><td>0V (GND)</td></tr></tbody></table>

**Connector P25 (UART13/14:**

<table><thead><tr><th width="129.33333333333331">Pin #</th><th>Signal</th><th>Specification</th></tr></thead><tbody><tr><td>1</td><td>5V</td><td>Limited 5V Output (Optional)</td></tr><tr><td>2</td><td>TX (UART13)</td><td>3.3V</td></tr><tr><td>3</td><td>RX (UART13)</td><td>3.3V</td></tr><tr><td>4</td><td>TX (UART14)</td><td>3.3V</td></tr><tr><td>5</td><td>RX (UART14)</td><td>3.3V</td></tr><tr><td>6</td><td>GND</td><td>0V (GND)</td></tr></tbody></table>