--- title: Wiring the Unit slug: microdrive-lpi/wiring-the-unit icon: {"faIcon":"fa-solid fa-network-wired"} docTags: createdAt: 2024-01-12T04:47:17.052Z --- Information on recommended wiring configuration of the micro**DRIVE** LPi units. It is an overview of the micro**DRIVE** LPi, including port numbering, pinouts and purpose. ## microDRIVE LPi ![](https://api.archbee.com/api/optimize/MIXUvgEo5LjmssoyMwenk/9Hr48HuVwrRf9sWGUawdn_image.png) ### Pinout The pinout for micro**DRIVE** LPi units can be found below. | **Port Number** | **Description** | | --------------- | ---------------------------------------------------- | | 1 | USB port. | | 2 | Main bus positive (+) | | 3 | Serial and telemetry connector (5-pin) | | 4 | Main bus negative (-) | | 5 | Multi-colour status LED | | 6 | Motor phase cables (A,B,C) | | 7 | Motor sensor connector (6-pin) | | 8, 9 | CAN Bus connectors, twinned for pass-through (4-pin) | **Serial and Telemetry Connector** The pinout for the 5-pin signal and telemetry port. ![](https://api.archbee.com/api/optimize/MIXUvgEo5LjmssoyMwenk/RC9iubYkU6ZZ_9OnUtK7p_control-signal.png "Serial and Telemetry Connector") **Motor Sensor Connector** The pinout for the 6-pin motor sensor connector. ![](https://api.archbee.com/api/optimize/MIXUvgEo5LjmssoyMwenk/0N4OFU5rOfu0GT3eynMI3_motor-signal.png "Motor Sensor Connector") **CAN Bus Connector** The pinout for the 4-pin CAN bus connector. ![](https://api.archbee.com/api/optimize/MIXUvgEo5LjmssoyMwenk/PMvGYGGEwJ91oTDPPt1Z9_can.png "CAN bus connector") ## Port and Pin Tolerances The electrical limits of each port and pin on the micro**DRIVE **units can be found below. Due to isolated interfaces, ground reference points will vary. | **Port/Pin ** | **Max Current (mA)** | **Abs Max Voltage (V)** | **Abs Min Voltage (V)** | **Passive Loading** | | ------------------ | ---------------------- | ----------------------- | ----------------------- | -------------------------------------------------------------------------------------------------------------- | | Main Bus | - | 58.8 | 15 | - | | Motor Phases | - | V\_Bus + 0.6 | -0.6 | - | | CAN H, CAN L | 115, Differential Mode | CAN\_GND + 12 | CAN\_GND - 12 | Configurable termination when powered. | | CAN GND | - | Bus\_GND + 0.2 | Bus\_GND - 0.2 | - | | UART RX | 10 | Sig\_GND + 3.4 | Sig\_GND - 0.3 | Pulled to 3.3 V via a 5.1k resistor. | | UART TX | 10 | Sig\_GND + 3.4 | Sig\_GND - 0.3 | Open drain, pulled to 3.3 V via 5.1k resistor. | | Telemetry Out | 10 | Sig\_GND + 3.4 | Sig\_GND - 0.3 | Pulled to 3.3 V via a 5.1k resistor. Bidirectional DShot response driven with an output impedance of 120 Ohms. | | Signal In | 10 | Sig\_GND + 3.4 | Sig\_GND - 0.3 | - | | Vcc In | 30 | Sig\_GND + 18 | Sig\_GND + 3.3 | Pulled to 3.3 V via 2.7k resistor. | | Hall A B C | 1 | Bus\_GND + 3.3 | Bus\_GND - 0.2 | - | | NTC In | 0.33 | Bus\_GND + 3.3 | Bus\_GND | - | | 5V Out Hall | 20 | 5.25 | 4.75 | - | ## Wiring Diagram The micro**DRIVE** units can be used in two primary configurations: CAN mode or serial mode (DShot and PWM). The wiring between the two systems differs and is covered below. **microDRIVE - CAN wiring** There are two primary methods of wiring CAN nodes, either as a bus (imaged below) or as a star network (stubs). If stubs are used, keeping the stub length below 1m is important (the DroneCAN specification recommends a maximum of 0.3 m \[11.8 in]). ![](https://api.archbee.com/api/optimize/MIXUvgEo5LjmssoyMwenk/HmCjsGRbh5kgVm-NPQ-IH_lpi-can-wiring.png "microDRIVE LPi CAN wiring diagram.") **microDRIVE - Serial wiring** The 5V and signal ground connections should be star-connected to a PDB when operating within a serial configuration. ![](https://api.archbee.com/api/optimize/d4raivS6AKDlg0WTpg-xm-XXCniiti8YffRmwUruV3C-20250902-033515.png "microDRIVE LPi serial wiring diagram.") **5V Connection** :::hint{type="info"} The 5V connection is not required for CAN on micro**DRIVE **LPi, as the CAN is non-isolated. However, it is internally connected to the 5V input and can be used for power passthrough on the LPi units. ::: The 5V input line is used to power the onboard isolation circuitry, which isolates the serial protocol inputs and telemetry lines (PWM or DShot signalling). This provides an isolated signal input from the power ground for increased noise immunity and isolated telemetry output. The 5V is commonly wired between each ESC. **The recommended supply is the PDB500 5V output**. When using the 5V line, it should be treated as a critical signal line. Loss of 5V will result in loss of serial input signal. Ground connections should be star-connected at PDB wherever possible. ### Capacitance Sufficient input capacitance is vital in ensuring any motor controller's safe and efficient operation. It is crucial to physically verify the availability of adequate capacitance for a specific application. It is recommended to maintain a maximum input lead length of 3 metres (9 ft) before considering the need for additional capacitance. It is essential to monitor input ripple at this length closely. To do this, install the motor controller in its intended use application and apply the maximum load the unit will see in service. Measure the voltage ripple at the input terminals to the motor controller. The ripple must be less than 5% of the bus voltage. The micro**DRIVE** LPi also measures and logs input ripple. ## Motor Selection A motor controller is only one part of a larger propulsion system. Selecting a system with an appropriate motor for the load is important to achieve peak performance. The KV of the motor should result in the motor reaching maximum operational speed at bus voltage. :::hint{type="info"} More details about this can be found in this[ Blog Post.](https://www.hargravetechnologies.com/news/2023/how-to-size-a-powertrain) ::: This ensures the peak load on the controller occurs at 100% motor duty cycle, where the controller is the most efficient. [We offer powertrain selection services](https://www.hargravetechnologies.com/company/about-hargrave-technologies). ## Secondary Arming Switch Connect a switch between PIN 1 (RXD) on the signal and telemetry connector and PIN 5 (GND). When PIN 1 is pulled to ground, drive will be enabled when the secondary arming switch feature is enabled. Note that 5V must be provided to the signal and telemetry port with an external VCC source.