Communications

An overview of supported microDRIVE communications protocols.
Supported Communications Protocols
The microDRIVE units support the following control and telemetry protocols:
CAN Bus 2.0B Protocols
DroneCAN (previously known as UAVCAN v0.9)
DShot
DShot150 to DShot600 baud rates
Bi-directional DShot for RPM filtering
DShot UART telemetry
PWM servo pulse (1000-2000 us)
Relevant Settings
Settings that affect communications on the microDRIVE can be found below.
Communication Settings
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If CAN Bus is enabled within communication settings, the following DroneCAN settings can be adjusted.
CAN Bus Settings
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DroneCAN Setup
CAN Bus must be enabled within the microDRIVE settings for the unit to connect.
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The following instructions outline how to operate the ESC using DroneCAN via a suitable SLCAN adapter. Autopilots such as the Pixhawk Cube running Ardupilot can be configured to act as a SLCAN adapter. Ardupilot-specific setup instructions for DroneCAN can also be found here.
Connecting the ESC
In accordance with the CAN wiring diagram, each unit necessitates the connection of CAN H, CAN L, and CAN GND to the control point. It is imperative to ensure the correct termination of both ends of the CAN network to achieve optimal performance. Notably, the units have a configurable internal termination, which should be enabled as required.
Once the units are powered on, they can be effectively tested using the DroneCAN GUI tool. This tool serves as an interface for establishing connections, conducting tests, and monitoring telemetry from devices equipped with DroneCAN capabilities. Utilising a DroneCAN-capable device, such as a Cube Orange running Ardupilot, as a master node is a prerequisite. Once a successful connection is established with the master node, users are presented with the following screen:
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DroneCAN GUI main screen
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Overview:
Section
Purpose
1
Setting for the master node ID. Required as the first setting to adjust when establishing the connection.
2
Start Dynamic Node Allocation server (DNA). ESCs will automatically connect to the network if CAN is enabled and the server is running.
3
List of connected Nodes in the current network.
4
Panels for access to telemetry viewers and ESC control panel.
5
The output of debug messages from devices connected to the network.
6
List of IDs of connected nodes.
ESC Operations
Once the ESC is connected to the network successfully as a node, further information can be accessed by double-clicking on it. The following screen is displayed:
DroneCAN Node Window
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Overview:
Section
Purpose
1
Selected node information, including hardware/software version, serial number (UID) and current status.
2
Restart Button. Trigger restart of the attached node. This will occur after a small timeout while the unit prepares for the shutdown. Blocked if the motor is armed.
3
Update Firmware Button. Select firmware for updates on this node. The file will be automatically transmitted, and a reboot will be triggered for installation. The result of the firmware update will be reported upon reboot. Blocked if the motor is armed.
4
Fetch All Settings Button. Fetch all the settings on the ESC. Blocked if the motor is armed.
5
Store All Settings Button. Save all the settings. Required after modification of settings, will trigger a reboot to apply settings. Blocked if the motor is armed.
6
Erase All Settings Button. Reset settings to defaults (defaults set by firmware). Blocked if the motor is armed.
7
Settings are listed after fetch. Double-click on the setting to adjust.
Running the ESC
When using the DroneCAN GUI to run the ESC, the following panel is used to operate connected ESC nodes (click the Panels drop-down menu, ESC Panel).
While this panel is open, the master node will exclusively send out motor output packets that clear any signal errors.
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ESC control panel within DroneCAN GUI
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Overview:
Section
Purpose
1
Channel Output Setpoints. Outputs are used to control the individual setpoints for channel outputs. Each ESC requires DroneCAN ESC Index setting to be applied to the desired channel number. The default is 0. The 0th channel represents the leftmost channel. The output range allows for full forward and full reverse movement. However, it's important to note that the ESC will only accept reverse setpoints (negative values) in Reversible mode.
2
Toggle to output the Armed Command message. Required if Require Armed Status DroneCAN setting enabled.
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DroneCAN Status Error Flags
The exact structure is currently undergoing integration and testing and may change in the future. Please refer to changelogs for more information.
1034 ESC Status
To quickly reveal error conditions and warnings, the DroneCAN Status Message 1034 error_counter field is used as a custom error/warning flag bitfield instead of counting total errors. This deviates from the DroneCAN specification.
When there are no errors, this field will always read 0. When an error or warning condition is active, the Most Significant Bit (MSB, bit index 31) is set to signal that this is a custom warning. From there, the flags are set to true according to the following conditions.
Bit Position
Error/Warning
Description
0
Over Temperature
Temperature has exceeded the configured temperature limit
1
Bus Over Current
Bus current has exceeded the configured bus current limit
2
Phase Over Current
Phase current has exceeded the configured phase current limit
3
Over Voltage
Bus voltage has crossed over the over-voltage threshold
4
Under Voltage
Bus voltage has crossed under the under-voltage threshold
5
Excess Voltage Ripple
Bus voltage ripple is outside tolerances. This can lead to shorter lifetime on the capacitors. This can also signal unit degradation and require investigation.
6
Signal Error
Set if signal receive has timed out
7
Motor Saturated
Detected a motor saturation and started reducing output drive (foldback) until control is regained
8
Motor Over Temperature
Motor temperature has exceeded the configured motor temperature limit
9
RPM Limit Reached
Controller has reached the configured maximum rpm limit
10
Error Active
Controller has entered error state
11
Output Shorted
Bridge detected as shorted during the startup short circuit test
12
Startup Check Failed
Bridge and Comparators have failed startup checks
31
Custom Status
Set to true to indicate this custom bitfield is in use
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1036 ESC Status Extended
The DroneCAN Status Message 1036 status_flags field is used to communicate more states. This is at a lower frequency to the 1034 Status Message, and is used for less time critical statuses.
Bit Position
Error/Warning
Description
0
Motor Armed
Controller is in an armed state and can drive the motor
1
Motor Running
Controller is actively driving the motor
2
Motor Parked
Controller is parked
3
Active Free Wheeling Engaged
Active Free Wheeling has been engaged
4
Ignoring Calibration
Unit calibration values are being ignored
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UART Telemetry Format
The format is currently undergoing integration and testing, it may change in future.
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When the telemetry output is enabled and the format is set as UART telemetry, the following packet format is output through the telemetry line at the configured rate.
Settings that affect telemetry on the microDRIVE can be found below.
Telemetry Settings
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UART Port Settings
The settings applied to the UART connection that supplies the telemetry packet can be found below:
Baud Rate: 115200 Baud
Word Length: 8B
Stop Bits: 1
Parity: None
No Flow Control
Packet Structure
The following packet is output at the configured rate. No partial packets are transmitted.
Data Field
Size
Comments
Bus Voltage
32-bit Float
The measured input voltage to the ESC. Units are Volts.
Bus Current
32-bit Float
The measured input current to the ESC. Units are Amps. Negative values indicate regenerative current.
Bridge Temperature
32-bit Float
The temperature of the 3-phase bridge. This is the primary heat source with the ESC. Units are in degrees Celcius.
ERPM
Unsigned 32-bit Integer
The current applied speed of the motor. Reports electrical RPM when the motor pole pair count is set to 1; mechanical RPM otherwise.
Input Duty Cycle
Unsigned 16-bit Integer
The requested duty cycle, as reported by the input signal system. 0-100%. 
Output Duty Cycle
Unsigned 16-bit Integer
The current applied duty cycle to the 3-phase bridge. If this does not equal the input duty cycle, the ESC is actively limiting the output. 0-100%.
Error Flags
Unsigned 32-bit Integer
This indicates the currently active error flags during operation, which should be seriously reviewed. See the Errors 1 guide within Diagnostics.
Reserved
Unsigned 16-bit Integer
Reserved for future use. Value fixed at 0.
Checksum (CRC32)
Unsigned 32-bit Integer
-
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Section	Purpose
1	Setting for the master node ID. Required as the first setting to adjust when establishing the connection.
2	Start Dynamic Node Allocation server (DNA). ESCs will automatically connect to the network if CAN is enabled and the server is running.
3	List of connected Nodes in the current network.
4	Panels for access to telemetry viewers and ESC control panel.
5	The output of debug messages from devices connected to the network.
6	List of IDs of connected nodes.

Section	Purpose
1	Selected node information, including hardware/software version, serial number (UID) and current status.
2	Restart Button. Trigger restart of the attached node. This will occur after a small timeout while the unit prepares for the shutdown. Blocked if the motor is armed.
3	Update Firmware Button. Select firmware for updates on this node. The file will be automatically transmitted, and a reboot will be triggered for installation. The result of the firmware update will be reported upon reboot. Blocked if the motor is armed.
4	Fetch All Settings Button. Fetch all the settings on the ESC. Blocked if the motor is armed.
5	Store All Settings Button. Save all the settings. Required after modification of settings, will trigger a reboot to apply settings. Blocked if the motor is armed.
6	Erase All Settings Button. Reset settings to defaults (defaults set by firmware). Blocked if the motor is armed.
7	Settings are listed after fetch. Double-click on the setting to adjust.

Section	Purpose
1	Channel Output Setpoints. Outputs are used to control the individual setpoints for channel outputs. Each ESC requires DroneCAN ESC Index setting to be applied to the desired channel number. The default is 0. The 0th channel represents the leftmost channel. The output range allows for full forward and full reverse movement. However, it's important to note that the ESC will only accept reverse setpoints (negative values) in Reversible mode.
2	Toggle to output the Armed Command message. Required if Require Armed Status DroneCAN setting enabled.

Bit Position	Error/Warning	Description
0	Over Temperature	Temperature has exceeded the configured temperature limit
1	Bus Over Current	Bus current has exceeded the configured bus current limit
2	Phase Over Current	Phase current has exceeded the configured phase current limit
3	Over Voltage	Bus voltage has crossed over the over-voltage threshold
4	Under Voltage	Bus voltage has crossed under the under-voltage threshold
5	Excess Voltage Ripple	Bus voltage ripple is outside tolerances. This can lead to shorter lifetime on the capacitors. This can also signal unit degradation and require investigation.
6	Signal Error	Set if signal receive has timed out
7	Motor Saturated	Detected a motor saturation and started reducing output drive (foldback) until control is regained
8	Motor Over Temperature	Motor temperature has exceeded the configured motor temperature limit
9	RPM Limit Reached	Controller has reached the configured maximum rpm limit
10	Error Active	Controller has entered error state
11	Output Shorted	Bridge detected as shorted during the startup short circuit test
12	Startup Check Failed	Bridge and Comparators have failed startup checks
31	Custom Status	Set to true to indicate this custom bitfield is in use

Bit Position	Error/Warning	Description
0	Motor Armed	Controller is in an armed state and can drive the motor
1	Motor Running	Controller is actively driving the motor
2	Motor Parked	Controller is parked
3	Active Free Wheeling Engaged	Active Free Wheeling has been engaged
4	Ignoring Calibration	Unit calibration values are being ignored

Data Field	Size	Comments
Bus Voltage	32-bit Float	The measured input voltage to the ESC. Units are Volts.
Bus Current	32-bit Float	The measured input current to the ESC. Units are Amps. Negative values indicate regenerative current.
Bridge Temperature	32-bit Float	The temperature of the 3-phase bridge. This is the primary heat source with the ESC. Units are in degrees Celcius.
ERPM	Unsigned 32-bit Integer	The current applied speed of the motor. Reports electrical RPM when the motor pole pair count is set to 1; mechanical RPM otherwise.
Input Duty Cycle	Unsigned 16-bit Integer	The requested duty cycle, as reported by the input signal system. 0-100%.
Output Duty Cycle	Unsigned 16-bit Integer	The current applied duty cycle to the 3-phase bridge. If this does not equal the input duty cycle, the ESC is actively limiting the output. 0-100%.
Error Flags	Unsigned 32-bit Integer	This indicates the currently active error flags during operation, which should be seriously reviewed. See the Errors 1 guide within Diagnostics.
Reserved	Unsigned 16-bit Integer	Reserved for future use. Value fixed at 0.
Checksum (CRC32)	Unsigned 32-bit Integer	-

Settings

Power Supply