> For the complete documentation index, see [llms.txt](https://docs.holybro.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.holybro.com/autopilot/pixhawk-baseboards/pixhawk-rpi-cm4-5-baseboard/connections-and-ports.md).

# Connections & Ports

{% hint style="info" %}
This baseboard is compatible with both Pixhawk 5X & 6X, and any flight controller that follows the Pixhawk Bus Standard.
{% endhint %}

<figure><img src="https://2367252986-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FLIgtGDAvVGkCKGOJb1bR%2Fuploads%2FHdcpbFPIbRT0ouM6KUyV%2FCM4_Baseboard_Ports.jpg?alt=media&amp;token=bca3ecc1-7189-4821-9236-0a08a31b0709" alt=""><figcaption></figcaption></figure>

{% hint style="info" %}
This baseboard is compatible with both Raspberry Pi CM4 and CM5 modules. The CM4 USB and Ethernet port names match the silk print on the baseboard's case.
{% endhint %}

### **Connection Between RPi CM4/5 & Flight Controller:**

FC Module is internally connected to the RPi CM4/5 through TELEM2

* CM4/5 GPIO14 <-> FMU TXD TELEM2
* CM4/5 GPIO15 <-> FMU RXD TELEM2
* CM4/5 GPIO16 <-> FMU CTS TELEM2
* CM4/5 GPIO17 <-> FMU RTS TELEM2

### **CM4 Slave USB-C port:**

CM4/5 USB Device Port. Use for CM4/5 Power and image flash. Max input voltage: 5V

### **CM4 Host1 & Host2  USB-C Port:**&#x20;

CM4/5 USB Host port. 1A Current output limit for each port.

### **Micro HDMI:**&#x20;

CM4/5 Video Output

### **Dip Switch**

![](https://2367252986-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FLIgtGDAvVGkCKGOJb1bR%2Fuploads%2Fvthc40V3NUXIluDBXlLn%2FCM4_DipSwitch.jpg?alt=media\&token=30486de3-c56b-4290-bc82-6608db36dc78)

|      | CM4 Slave                                     | CM4 Host1&2                                    |
| ---- | --------------------------------------------- | ---------------------------------------------- |
| RPI  | <p>Data Connected</p><p>Power IN and Data</p> | <p>Data Not Connected</p><p>Power out only</p> |
| EMMC | <p>Data Not Connected</p><p>Power IN only</p> | <p>Data Connected</p><p>Power out and Data</p> |

<figure><img src="https://2367252986-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FLIgtGDAvVGkCKGOJb1bR%2Fuploads%2FXilDQZLsYfrk92ic1T6v%2FCM4_USB_Switch.png?alt=media&amp;token=b1aee0e9-c510-44d2-bb46-490058656c70" alt=""><figcaption></figcaption></figure>

{% hint style="info" %}
Refer to this diagram for location of pin1. All connectors are JST GH 1.25 mm Pitch unless noted otherwise.&#x20;

![](https://2367252986-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FLIgtGDAvVGkCKGOJb1bR%2Fuploads%2F5ztMPc8sZRkgBLuofQ25%2FPin%20Number.png?alt=media\&token=33990df2-0d2d-4b45-9a4f-ead799af93fe)
{% endhint %}

### **CM4 ETH  port**

<table data-header-hidden data-search="false"><thead><tr><th></th><th></th><th></th></tr></thead><tbody><tr><td>Pin</td><td>Signal</td><td>Volt</td></tr><tr><td>1(red)</td><td>CM4/5_TRD0_P</td><td>+3.3V</td></tr><tr><td>2(pink)</td><td>CM4/5_TRD0_N</td><td>+3.3V</td></tr><tr><td>3(yellow)</td><td>CM4/5_TRD1_P</td><td>+3.3V</td></tr><tr><td>4(green)</td><td>CM4/5_TRD1_N</td><td>+3.3V</td></tr><tr><td>5(brown)</td><td>CM4/5_TRD2_P</td><td>+3.3V</td></tr><tr><td>6(blue)</td><td>CM4/5_TRD2_N</td><td>+3.3V</td></tr><tr><td>7(purple)</td><td>CM4/5_TRD3_P</td><td>+3.3V</td></tr><tr><td>8(black)</td><td>CM4/5_TRD3_N</td><td>+3.3V</td></tr></tbody></table>

### **FC ETH Port**

| **Pin**  | **Signal** | **Volt** |
| -------- | ---------- | -------- |
| 1(red)   | RXN        | +3.3V    |
| 2(black) | RXP        | +3.3V    |
| 3(black) | TXN        | +3.3V    |
| 4(black) | TXP        | +3.3V    |

<figure><img src="https://2367252986-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FLIgtGDAvVGkCKGOJb1bR%2Fuploads%2FafeCsTbUXasWlZcCQT0m%2FCM4%20Ethernet.png?alt=media&amp;token=f71ad010-d530-443c-90a4-46e291c3d14f" alt=""><figcaption><p>FC &#x26; CM4 connected via ethernet using cabled provided.</p></figcaption></figure>

### **FAN port**

{% hint style="info" %}
The 5V source for the fan is not shared with the USB 5V that powers the RPi compute module.
{% endhint %}

| Pin      | Signal | Volt |
| -------- | ------ | ---- |
| 1(red)   | VCC    | +5V  |
| 2(black) | GND    | GND  |

### **CAMERA  Port** (Use for CSI Camera IN)

<table data-header-hidden data-search="false"><thead><tr><th></th><th></th><th></th></tr></thead><tbody><tr><td>Pin</td><td>Signal</td><td>Volt</td></tr><tr><td>1</td><td>GND</td><td>GND</td></tr><tr><td>2</td><td>CM4/5_CAM1_D0_N</td><td>+3.3V</td></tr><tr><td>3</td><td>CM4/5_CAM1_D0_P</td><td>+3.3V</td></tr><tr><td>4</td><td>GND</td><td>GND</td></tr><tr><td>5</td><td>CM4/5_CAM1_D1_N</td><td>+3.3V</td></tr><tr><td>6</td><td>CM4/5_CAM1_D1_P</td><td>+3.3V</td></tr><tr><td>7</td><td>GND</td><td>GND</td></tr><tr><td>8</td><td>CM4/5_CAM1_CLK_N</td><td>+3.3V</td></tr><tr><td>9</td><td>CM4/5_CAM1_CLK_P</td><td>+3.3V</td></tr><tr><td>10</td><td>GND</td><td>GND</td></tr><tr><td>11</td><td>CM4/5_CAM1_D2_N</td><td>+3.3V</td></tr><tr><td>12</td><td>CM4/5_CAM1_D2_P</td><td>+3.3V</td></tr><tr><td>13</td><td>GND</td><td>GND</td></tr><tr><td>14</td><td>CM4/5_CAM1_D3_N</td><td>+3.3V</td></tr><tr><td>15</td><td>CM4/5_CAM1_D3_P</td><td>+3.3V</td></tr><tr><td>16</td><td>GND</td><td>GND</td></tr><tr><td>17</td><td>CM4/5_CAM1_GPIO</td><td>+3.3V</td></tr><tr><td>18</td><td>No Connected</td><td>--</td></tr><tr><td>19</td><td>GND</td><td>GND</td></tr><tr><td>20</td><td>CM4/5_I2C0_SCL</td><td>+3.3V</td></tr><tr><td>21</td><td>CM4/5_I2C0_SDA</td><td>+3.3V</td></tr><tr><td>22</td><td>CM4/5_VDD_3V3</td><td>+3.3V</td></tr></tbody></table>

### **Power1 (Main) & Power2 Port (Backup)** (2.00mm Pitch CLIK-Mate)

<table data-header-hidden data-search="false"><thead><tr><th></th><th></th><th></th></tr></thead><tbody><tr><td><strong>Pin</strong></td><td><strong>Signal</strong></td><td><strong>Volt</strong></td></tr><tr><td>1(red)</td><td>VDD5V_BRICK1/2</td><td>+5V</td></tr><tr><td>2(black)</td><td>VDD5V_BRICK1/2</td><td>+5V</td></tr><tr><td>3(black)</td><td>SCL1/2</td><td>+3.3V</td></tr><tr><td>4(black)</td><td>SDA1/2</td><td>+3.3V</td></tr><tr><td>5(black)</td><td>GND</td><td>GND</td></tr><tr><td>6(black)</td><td>GND</td><td>GND</td></tr></tbody></table>

### **Telem1, Telem2, Telem3 ports**

<table data-header-hidden data-search="false"><thead><tr><th></th><th></th><th></th></tr></thead><tbody><tr><td><strong>Pin</strong></td><td><strong>Signal</strong></td><td><strong>Volt</strong></td></tr><tr><td>1(red)</td><td>VCC</td><td>+5V</td></tr><tr><td>2(black)</td><td>TX7/5/2 (out)</td><td>+3.3V</td></tr><tr><td>3(black)</td><td>RX7/5/2 (in)</td><td>+3.3V</td></tr><tr><td>4(black)</td><td>CTS7/5/2 (in)</td><td>+3.3V</td></tr><tr><td>5(black)</td><td>RTS7/5/2 (out)</td><td>+3.3V</td></tr><tr><td>6(black)</td><td>GND</td><td>GND</td></tr></tbody></table>

### **GPS 1 Port**

<table data-header-hidden data-search="false"><thead><tr><th></th><th></th><th></th></tr></thead><tbody><tr><td><strong>Pin</strong></td><td><strong>Signal</strong></td><td><strong>Volt</strong></td></tr><tr><td>1(red)</td><td>VCC</td><td>+5V</td></tr><tr><td>2 black)</td><td>TX1(out)</td><td>+3.3V</td></tr><tr><td>3(black)</td><td>RX1(in)</td><td>+3.3V</td></tr><tr><td>4(black)</td><td>SCL1</td><td>+3.3V</td></tr><tr><td>5(black)</td><td>SDA1</td><td>+3.3V</td></tr><tr><td>6(black)</td><td>SAFETY_SWITCH</td><td>+3.3V</td></tr><tr><td>7(black)</td><td>SAFETY_SWITCH_LED</td><td>+3.3V</td></tr><tr><td>8(black)</td><td>VDD_3V3</td><td>+3.3V</td></tr><tr><td>9(black)</td><td>BUZZER-</td><td>0~5V</td></tr><tr><td>10(black)</td><td>GND</td><td>GND</td></tr></tbody></table>

### **GPS 2 Port**

<table data-header-hidden data-search="false"><thead><tr><th></th><th></th><th></th></tr></thead><tbody><tr><td><strong>Pin</strong></td><td><strong>Signal</strong></td><td><strong>Volt</strong></td></tr><tr><td>1(red)</td><td>VCC</td><td>+5V</td></tr><tr><td>2 black)</td><td>TX8(out)</td><td>+3.3V</td></tr><tr><td>3(black)</td><td>RX8(in)</td><td>+3.3V</td></tr><tr><td>4(black)</td><td>SCL2</td><td>+3.3V</td></tr><tr><td>5(black)</td><td>SDA2</td><td>+3.3V</td></tr><tr><td>6(black)</td><td>GND</td><td>GND</td></tr></tbody></table>

### **CAN1, CAN2 ports**

| **Pin**  | **Signal** | **Volt** |
| -------- | ---------- | -------- |
| 1(red)   | VCC        | +5V      |
| 2(black) | CANH1/2    | +3.3V    |
| 3(black) | CANL1/2    | +3.3V    |
| 4(black) | GND        | GND      |

### **Uart4 & I2C port**

<table data-header-hidden data-search="false"><thead><tr><th></th><th></th><th></th></tr></thead><tbody><tr><td><strong>Pin</strong></td><td><strong>Signal</strong></td><td><strong>Volt</strong></td></tr><tr><td>1(red)</td><td>VCC</td><td>+5V</td></tr><tr><td>2(black)</td><td>TX4(out)</td><td>+3.3V</td></tr><tr><td>3(black)</td><td>RX4(in)</td><td>+3.3V</td></tr><tr><td>4(black)</td><td>SCL3</td><td>+3.3V</td></tr><tr><td>5(black)</td><td>SDA3</td><td>+3.3V</td></tr><tr><td>6(black)</td><td>NFC_GPIO</td><td>+3.3V</td></tr><tr><td>7(black)</td><td>GND</td><td>GND</td></tr></tbody></table>

### **SPI Port**

<table data-header-hidden data-search="false"><thead><tr><th></th><th></th><th></th></tr></thead><tbody><tr><td><strong>Pin</strong></td><td><strong>Signal</strong></td><td><strong>Volt</strong></td></tr><tr><td>1(red)</td><td>VCC</td><td>+5V</td></tr><tr><td>2 (black)</td><td>SPI6_SCK</td><td>+3.3V</td></tr><tr><td>3(black)</td><td>SPI6_MISO</td><td>+3.3V</td></tr><tr><td>4(black)</td><td>SPI6_MOSI</td><td>+3.3V</td></tr><tr><td>5(black)</td><td>SPI6_CS1</td><td>+3.3V</td></tr><tr><td>6(black)</td><td>SPI6_CS2</td><td>+3.3V</td></tr><tr><td>7(black)</td><td>SPIX_SYNC</td><td>+3.3V</td></tr><tr><td>8(black)</td><td>SPI6_DRDY1</td><td>+3.3V</td></tr><tr><td>9(black)</td><td>SPI6_DRDY2</td><td>+3.3V</td></tr><tr><td>10(black)</td><td>SPI6_nRESET</td><td>+3.3V</td></tr><tr><td>11(black)</td><td>GND</td><td>GND</td></tr></tbody></table>

### **USB Port**

| **Pin**  | **Signal** | **Volt** |
| -------- | ---------- | -------- |
| 1(red)   | VBUS       | +5V      |
| 2(black) | DM         | +3.3V    |
| 3(black) | DP         | +3.3V    |
| 4(black) | GND        | GND      |

### **I2C Port**

| **Pin**  | **Signal** | **Volt** |
| -------- | ---------- | -------- |
| 1(red)   | VCC        | +5V      |
| 2(black) | SCL3       | +3.3V    |
| 3(black) | SDA3       | +3.3V    |
| 4(black) | GND        | GND      |

### **ETH Port**

| **Pin**  | **Signal** | **Volt** |
| -------- | ---------- | -------- |
| 1(red)   | RXN        | +3.3V    |
| 2(black) | RXP        | +3.3V    |
| 3(black) | TXN        | +3.3V    |
| 4(black) | TXP        | +3.3V    |

### **AD\&IO Port**

<table data-header-hidden data-search="false"><thead><tr><th></th><th></th><th></th></tr></thead><tbody><tr><td><strong>Pin</strong></td><td><strong>Signal</strong></td><td><strong>Volt</strong></td></tr><tr><td>1(red)</td><td>VCC</td><td>+5V</td></tr><tr><td>2(black)</td><td>FMU_CAP1</td><td>+3.3V</td></tr><tr><td>3(black)</td><td>FMU_BOOTLOADER</td><td>+3.3V</td></tr><tr><td>4(black)</td><td>FMU_RST_REQ</td><td>+3.3V</td></tr><tr><td>5(black)</td><td>NARMED</td><td>+3.3V</td></tr><tr><td>6(black)</td><td>ADC1_3V3</td><td>+3.3V</td></tr><tr><td>7(black)</td><td>ADC1_6V6</td><td>+6.6V</td></tr><tr><td>8(black)</td><td>GND</td><td>GND</td></tr></tbody></table>

### **DSM RC Port** (JST-ZH 1.5mm Pitch)

| **Pin**   | **Signal**         | **Volt** |
| --------- | ------------------ | -------- |
| 1(yellow) | VDD\_3V3\_SPEKTRUM | +3.3V    |
| 2(black)  | GND                | GND      |
| 3(gray)   | DSM/SPEKTRUM IN    | +3.3V    |

### **RC IN Port**

| **Pin** | **Signal**   | **Volt** |
| ------- | ------------ | -------- |
| S       | SBUS/PPM in  | +3.3V    |
| +       | VDD\_5V \_RC | +5V      |
| -       | GND          | GND      |

### **IO Debug Port** (JST-SH 1mm Pitch)

<table data-header-hidden data-search="false"><thead><tr><th></th><th></th><th></th></tr></thead><tbody><tr><td><strong>Pin</strong></td><td><strong>Signal</strong></td><td><strong>Volt</strong></td></tr><tr><td>1(red)</td><td>IO_VDD_3V3</td><td>+3.3V</td></tr><tr><td>2 black)</td><td>IO_USART1_TX</td><td>+3.3V</td></tr><tr><td>3(black)</td><td>NC</td><td>--</td></tr><tr><td>4(black)</td><td>IO_SWD_IO</td><td>+3.3V</td></tr><tr><td>5(black)</td><td>IO_SWD_CK</td><td>+3.3V</td></tr><tr><td>6(black)</td><td>IO_SWO</td><td>+3.3V</td></tr><tr><td>7(black)</td><td>IO_SPARE_GPIO1</td><td>+3.3V</td></tr><tr><td>8(black)</td><td>IO_SPARE_GPIO2</td><td>+3.3V</td></tr><tr><td>9(black)</td><td>IO_nRST</td><td>+3.3V</td></tr><tr><td>10(black)</td><td>GND</td><td>GND</td></tr></tbody></table>

### **FMU Debug Port** (JST-SH 1mm Pitch)

<table data-header-hidden data-search="false"><thead><tr><th></th><th></th><th></th></tr></thead><tbody><tr><td><strong>Pin</strong></td><td><strong>Signal</strong></td><td><strong>Volt</strong></td></tr><tr><td>1(red)</td><td>FMU_VDD_3V3</td><td>+3.3V</td></tr><tr><td>2 black)</td><td>FMU_USART3_TX</td><td>+3.3V</td></tr><tr><td>3(black)</td><td>FMU_USART3_RX</td><td>+3.3V</td></tr><tr><td>4(black)</td><td>FMU_SWD_IO</td><td>+3.3V</td></tr><tr><td>5(black)</td><td>FMU_SWD_CK</td><td>+3.3V</td></tr><tr><td>6(black)</td><td>SPI6_SCK_EXTERNAL1</td><td>+3.3V</td></tr><tr><td>7(black)</td><td>NFC_GPIO</td><td>+3.3V</td></tr><tr><td>8(black)</td><td>PH11</td><td>+3.3V</td></tr><tr><td>9(black)</td><td>FMU_nRST</td><td>+3.3V</td></tr><tr><td>10(black)</td><td>GND</td><td>GND</td></tr></tbody></table>

### **RSSI Port**

| **Pin** | **Signal**         | **Volt** |
| ------- | ------------------ | -------- |
| S       | SBUS\_OUT/RSSI\_IN | +3.3V    |
| +       | VDD\_SERVO         | 0\~36V   |
| -       | GND                | GND      |

### **FMU PWM OUT (AUX)**

| **Pin** | **Signal**  | **Volt** |
| ------- | ----------- | -------- |
| S       | FMU\_CH1\~8 | +3.3V    |
| +       | VDD\_SERVO  | 0\~36V   |
| -       | GND         | GND      |

### **I/O PWM OUT (MAIN)**

| **Pin** | **Signal** | **Volt** |
| ------- | ---------- | -------- |
| S       | IO\_CH1\~8 | +3.3V    |
| +       | VDD\_SERVO | 0\~36V   |
| -       | GND        | GND      |


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