The **Pi-KVM v3 HAT Board** is designed to work with the **Raspberry Pi 4** and provides the following features:
* **HDMI capture** device with max resolution 1080p 50Hz and audio support
* **Keyboard** &**mouse** emulation
* **Mass storage emulation** (i.e., virtual flash drive or CD drive provided by image file saved on PiKVM)
* Ability to simulate "**removal and insertion**" for USB for above mentioned devices
* **ATX controller** (allowing to switch power even if target device is off or operating system hangs)
* Onboard **real-time clock**
* 5v PWM **fan controller**
* USB & RJ-45 **serial console**
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## Requirements
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To use Pi-KVM v3, you will need the following things, which are NOT included in the base kit:
* **Raspberry Pi 4** (a model with any amount of memory is suitable)
* **5.1v 3A** official Raspberry power supply with USB-C
* A regular **HDMI cable**
* **USB-C to USB-A cable** with DATA lines (for keyboard and mouse emulation)
* **Straight Ethernet cable** (NOT crossover, to connect the HAT board and ATX board)
* **Micro-SD** card at least **16 Gb class 10** is strongly recommended
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# Known issues & limitations
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* The actual frame rate of the image received via HDMI will depend on the network bandwidth, resolution and the load on the Raspberry Pi. This is usually ~20-24 FPS for 1080p over LAN.
* **AIMOS** switches are not fully compatible with the video capture device (as with regular HDMI CSI bridge).
* There may be **compatibility** issues with some motherboards (such as **HP** or **DELL**) which are the same as those that exist with Pi-KVM v2. Not everything is perfect, but if you have already used Pi-KVM v2 - our new v3 will work perfectly and please you. If there is no image from the BIOS, you can fine-tune the HDMI settings, but it is possible that the USB keyboard or Mass Storage devices will not be available in the BIOS.
* If you plan to use Pi-KVM v3 with an **Apple Mac**, then you should know that you won't be able to get into UEFI or Recovery Mode. Inside macOS, the device will work fine. To use with Apple UEFI, you need to purchase our AUM board (Advanced USB Module, a small optional device for Pi-KVM v3), which will be available soon.
5.**Important!** If you are going to use GPIO pins to control a relay, KVM switch, or anything else, be sure to check the v3 shield pinout. Many ports are busy with internal functions. Before using them for your own use, you must disable them, otherwise you may damage the device.
5.1v 3A is strongly recommended. The official Raspberry Pi 4 power supply is perfect for this.
2.**Power (green) and activity (red) LEDs**
Show the device status. The red LED lights up when there is disk activity.
3.**USB serial console**
Hardware serial console to login and configure the Raspberry Pi via a terminal emulator. It operates at a speed of 115200 baud. Just plug in the USB and you will see a USB-TTL device on your host.
4.**USB serial console status LED**
The console has independent power from the USB connected host, so you can reboot the Pi and not lose the connection to the console. The LED indicates the presence of power via USB.
5.**COM serial console**
For connection, the so-called CISCO-style serial cable is used (on the one hand, RJ45, on the other, COM port). You can buy any suitable cable or [make your own](https://wiki.mikrotik.com/wiki/Manual:System/Serial_Console). If you do not need console access to the Pi-KVM, this port can be used to access the server.
6.**PoE pins**
Pi-KVM is compatible with PoE hats. These pins are used for power supply.
7.**UART jumpers**
The two jumpers installed here provide communication between the console ports (3, 5) and the UART of Raspberry. By removing them, you will get access to the UART.
8.**Audio capture jumpers**
The Pi-KVM can capture audio. Although this is not yet implemented in the software, the hardware capability is already present and you can use the `arecord` command to record audio. These pins are used for this purpose. If you need additional GPIO pins, you can remove these jumpers, comment line `dtoverlay=tc358743-audio` in `/boot/config.txt`, and use the [GPIO 19, 20 and 21](https://pinout.xyz/pinout/pin35_gpio19) as you see fit.
9.**HDMI reset jumper**
Currently unused. In the future, it will be used for hardware resetting of the video capture chip. If you remove it, you will be able to use the [GPIO 17](
https://pinout.xyz/pinout/pin11_gpio17)
10.**GPIO pins**
With the exception of the used pins, the rest are at your service.
Use the ethernet [straight cable](https://www.home-network-help.com/straight.html) to connect the ATX adapter (included). Connect the wires of the power button, reset button, and the power and HDD LEDs inside your server enclosure to the adapter.
