* Please review the back of the box. All parts are required before the HAT is fully functional.
* The USB-C bridge is located in with the ATX end which includes a pink foam spacer.
* Please assemble the HAT onto the RPi and test all of the parts before installing in the case, it's easier to install in the case than to dissasemble it.
If you have a kit without a metal case, you can use our free 3D printing case drawing: [V3.3](stl/v3.3/index.md){target=_blank} for the Kickstarter/Store model, [V3.2](stl/v3.2/index.md){target=_blank} for the pre-release.
* **HDMI input** and **USB emulation** port must be connected to the computer. Optionally, the **[ATX port](atx_board.md)** can be connected to control the power. There should be no USB hub between PiKVM and the computer, as some UEFI/BIOS cannot detect them at the boot stage. On the HDMI the HAT, like the CSI bridge, supports 1080p50Hz or 720p60Hz or lower.
5. ??? note "If your kit includes the OLED display and/or the fan, you'll need to turn them on (this is only needed for the older V3 image for the HAT, in the box image everything is enabled by default)"
Try restarting PiKVM using the `reboot` command executed in the terminal. If PiKVM hangs during boot (you can't get the Web Interface for a long time), then you are faced with this rare problem. **Don't worry, it's easy to fix.** Turn off the PiKVM, disconnect all cables from it, take a close look at the [diagram of its ports and jumpers](#io-ports-and-jumpers), and **remove jumper #14** (it is to the right of the CSI connector). Then you can connect and power up PiKVM again. Now everything will be fine. If you are interested in the technical background, it is described [here](https://www.kickstarter.com/projects/mdevaev/pikvm-v3-hat/posts/3296343). Also, just for information: not a single case of negative consequences from the removal of the jumper has been recorded.
**Before using GPIO** pins to control a relay, KVM switch, or anything else, be sure to [check the HAT pinout](#io-ports-and-jumpers). Many ports are busy with internal functions. Before using them for your own use, you must disable them, otherwise you may damage the device.
PiKVM V3 supports maximum resolution 1920x1080@50Hz, 60Hz will not work. You can use any other resolution less than the specified one, for example: 1600x1200@60Hz, 1280x720@60Hz, etc. If you have problems with the video, follow [this guide](edid.md).
6.**Serial console port** (default: /dev/ttyAMA0, RS232 input, outputs +6V/-6V, for the Raspberry Pi or server console access, use the [Cisco/Mikrotik-style](https://wiki.mikrotik.com/wiki/File:Rj45-pinout.gif.png) cable).
14.**CSI-2 interface** and **HDMI backpowering** jumper, see [Step 9 of the Basic Setup](#basic-setup). Open: (jumper removed) diode will stop current from HDMI input (backpower will be fixed), closed: (jumper connected to both pins) will allow current from HDMI device.
18.**USB-C emulation port** - this port is doing the emulation of a USB keyboard, mouse, Virtual CD-ROM or USB Flash Drive, USB-Ethernet, USB-Serial port and a lot of other Linux-supported features.
19.**1-Wire**&**Neo-pixel** interface (under, advanced user feature).
* **1-Wire [19]** - `GPIO 4` - Also available under ATX RJ-45 port (point [19] on the above) as bi-directional buffered open-drain 5V for regular 1-Wire usage.
* **UART** - `GPIO 14, 15` - Can be used as UART only for the serial console. When jumpers [5] are removed, you can connect to pins 14 and 15 directly using GPIO header. Also you can remove jumper [5] and disable UART console in the `/boot/config.txt` and `/boot/cmdline.txt` to use this pins for any purpose. But it's not recommended.
* **Red activity led on the front [8]** - `GPIO 13` - Can be disabled in `/boot/config.txt` and available on the Neo-pixel port [19].
* **PWM fan controller** - `GPIO 12`. Can be used for custom purposes if the fan disconnected and `kvmd-fan` service is stopped.
* **I2S HDMI sound** - `GPIO 18, 19, 20, 21`. Can be used for custom purposes if the `tc358743-audio` overlay in `/boot/config.txt` is disabled **AND** jumpers [4] are removed.
* **USB breaker** - `GPIO 5` - Can't be used for any other purposes.
* There may be **compatibility** issues with some motherboards (such as **HP** or **DELL**) which are the same as those that exist with PiKVM V2. Not everything is perfect, but if you have already used PiKVM V2 - our new V3 will work great and please you. If there is no image from the BIOS, you can fine-tune the HDMI settings, but it is possible that the Mass Storage devices will not be available in the BIOS.
