# Holybro Microhard P900 Radio The [Holybro Microhard P900 Radio](https://holybro.com/products/microhard-radio) integrates the [Microhard Pico Serial](https://microhardcorp.com/P900.php) P900 RF module, which is capable of delivering high-performance wireless serial communications in robust and secure mesh, point-to-point or point-to-multipoint topologies. It enables MAVLink communication between a radio on a vehicle and a GCS. This radio operate within the 902-928 MHz ISM frequency band, using frequency hopping spread spectrum (FHSS) technology, providing reliable wireless asynchronous data transfer between most equipment types which employ a serial interface. The radio may be configured as a primary coordinator, secondary coordinator, standby coordinator or remote in a mesh topology, or a master, repeater or remote in a PP or PMP topology. This versatility is very convenient for the user. This radio is configured using AT commands through the data port or using _PicoConfig_ application through the diagnosis port. The transmit power is software selectable from 100mW to 1W, with range up to 40 miles. A single ground station radio can be used to communicate with multiple vehicles using point to multi-point or mesh. Vehicles must have different MAVLINK IDs. ![Holybro Microhard Radio](../../assets/hardware/telemetry/holybro_microhard.jpg) ## 特性 - USB Type-C port, integrated USB to UART converter - 6-position JST-GH connector, can be directly connected to the TELEM port on various Pixhawk-standard flight controllers such [Pixhawk 4](../flight_controller/pixhawk4.md) & [Pixhawk 5X](../flight_controller/pixhawk5x.md) - High voltage BEC onboard, Support DC7~35V voltage supply - UART transmission & Three-stage RSSI LED indicator - Transmission within a public, license-exempt band of the radio spectrum - Transparent, low latency link rates up to 276 Kbps - Supports a robust true Mesh operation with auto-routing - 32 bits of CRC, selectable retransmission and forward error correction - Separate diagnostics port, transparent remote diagnostics and online network control ## 购买渠道 - [Holybro Microhard P900 Telemetry Radio (100mW - 1W)](https://holybro.com/products/microhard-radio) ## 技术规范 ## Connecting #### Vehicle Radio This radio comes with a 6-Pin JST GH cable that can be connected to the `TELEM1` port on flight controllers that are compliant with the Pixhawk connector standard. The radio must be separately powered via the 4-pin JST-GH XT30 power cable (7-35VDC). #### Ground Station Radio This radio has a internal USB to UART converter, the ground radio can be connected to the ground station via USB C. The radio must be separately powered via the XT30 power cable (7-35VDC). ## Setup/Configuration Holybro Microhard P900 Radios have been configured to point-to-point operating mode and 57600 serial baud rate in the factory. This allows them to connect to the PX4 `TELEM1` port and _QGroundControl_ **without any further configuration**. :::info You can use a different baud rate, mode or flight controller port. The only "requirement" is that the ground radio, air radio, PX4, and QGroundControl must all be set to the same baud rate. ::: [Microhard Serial Telemetry Radios > Configuration](../telemetry/microhard_serial.md#configuration) explains how to configure the radios, _QGroundControl_, and PX4. In order to configure the radios using the _PicoConfig_ application (as described in the link above) it must be connected through the diagnostic port: The diagnostic port uses a 4-position JST SH connector. If you use _PicoConfig_ application or special diagnostic commands to config the radio, you should connect to this port. The diagnostic port is 3.3V logic level compatible. A USB-to-serial board is needed for connecting the radio to your computer. You can purchase a [Holybro UART to USB Converter](https://holybro.com/products/uart-to-usb-converter). _Pico Config_ will automatically detect and connect to the configuration port. Adjust the settings so that the baud rate matches PX4 (and the ground station). Holding the **Config** button while powering-up the radio will boot the unit into COMMAND mode: the default serial interface will be active and temporarily set to operate at its default serial settings of 9600/8/N/1. Note that it is also possible to configure the radios using AT commands through the data port. ### Default Configuration The default radio configuration as shipped is shown in _PicoConfig_ below (you may need to reconfigure them as shown after firmware update or resetting the radio). In point-to-point operating modes, there must be a master to provide network synchronization for the system, so one radio should be configured to PP master and another should be configured to PP remote. ## LED 状态 The P900 Radio has 6 status LEDs: three are blue, two are orange, and one is green. The meanings of the different LEDs are: - Power LED(green) - This LED will illuminate when the P900 Radio is connected to a power source (7-35VDC). - TX LED (orange) - When illuminated, this LED indicates that the Radio is transmitting data over the air. - RX LED (orange) - This LED indicates that the Radio is synchronized and has received valid packets. - RSSI LEDs (3x Blue) - As the received signal strength increases, starting with the furthest left, the number of active - RSSI LEDs increases. Signal strength is calculated based on the last four valid received packets with correct CRC. The value of RSSI is reported in S123. ### 针脚定义 #### Diagnosis Port | 针脚 | 信号 | Voltage | | ---------------------------- | --- | --------------------- | | 1 | NC | -- | | 2 (black) | RX | +3.3V | | 3 (black) | TX | +3.3V | | 4 (black) | GND | GND | #### Data Port | 针脚 | 信号 | Voltage | | ---------------------------- | -------------------- | --------------------- | | 1（红） | NC | -- | | 2 (black) | RX | +3.3V | | 3 (black) | TX | +3.3V | | 4 (black) | CTS | +3.3V | | 5 (black) | RTS: | +3.3V | | 6 (black) | GND | GND | #### Power Port | 针脚 | 信号 | Voltage | | ---------------------------- | ---- | ------- | | 1（红） | BAT+ | 7-35V | | 2 (red) | BAT+ | 7-35V | | 3 (black) | BAT- | GND | | 4 (black) | BAT- | GND | ### 尺寸 ### Power Consumption - Supply voltage: DC7~35V from 4-pin JST-GH to XT30 (included) - Transmit current: 200 mA/7V at 20dBm - 350mA/7V at 27dBm - 800 mA/7V at 30dBm - Receive current: 100 mA - Weight: 42g (without antenna) ## 更多信息 - [Microhard Radio](https://docs.holybro.com/telemetry-radio/microhard-radio) (docs.holybro.com) - [Holybro Microhard P900 Downloads](https://docs.holybro.com/telemetry-radio/microhard-radio/download) (Manuals, and other docs) (Holybro)