Wiring the Unit - LP
Information on recommended wiring configuration of the microDRIVE units. It is an overview of the microDRIVE LP, including port numbering, pinouts and purpose.
The pinout for microDRIVE LP units can be found below. Cable colour is relevant to pre-cabled and cased units. The ports are referencing the image above.
Port Number | Description |
|---|---|
1 | USB port. The cover is sealed for IP rating and should be screwed on during use. |
2 | Main bus positive (+) |
3 | Signal and telemetry cable |
4 | Main bus negative (-) |
5 | Multi-colour status LED |
6 | Motor phase cables (A,B,C) |
7 | Motor sensor cable |
Signal and Telemetry Port
Cable Colour | Purpose |
|---|---|
Green | CAN Ground |
Yellow | CAN Low |
White | CAN High |
Black | Signal Ground |
Red | 5V Power |
Grey | Serial Signal (DShot/PWM) |
Purple | Serial Telemetry |
Blue | UART RX |
Bare Silver Wire | Cable shield connection. Should be connected flight controller side |
Motor Sensor Port
Cable Colour | Purpose |
|---|---|
Black | Sensor Port Ground |
Red | 5V Power |
Blue | Hall Effect Input C |
Green | Hall Effect Input B |
Yellow | Hall Effect Input A |
White | Motor Temperature Sensor (NTC or PTC) |
The microDRIVE LP units feature an optional shield connection integrated into the signal cable. This connection enables enhanced noise immunity through the termination of a shield around the cable. Its usage is optional, allowing for the removal of the wire if not needed.
For optimal effectiveness, it is recommended to connect the shield to the signal ground at the source, such as a flight controller. Alternatively, a power distribution board can serve as a centralised shield point.
If multiple shielded units are connected, they should be connected at a single point (forming a star connection).
The electrical limits of each port and pin on the microDRIVE 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 | - |
The microDRIVE 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 0.3m).
microDRIVE - Serial wiring
The 5V and signal ground connections should be star-connected to a power source (like the PDB500) when operating within a serial configuration.
The 5V connection is not required for CAN on microDRIVE, as the CAN is non-isolated.
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, or similar.
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.
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 keep the input lead length to a maximum 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 microDRIVE LP units also measure and log input ripple.
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.
More details about this can be found in this Blog Post.
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.