NCS32100 Rotary Inductive Position Sensor Evaluation Board User Manual
STR-NCS32100-GEVK
Introduction
The STR-NCS32100-GEVK evaluation board provides hardware and a PCB rotary sensor for full demonstration of the NCS32100. The block diagram below shows the signal path used to communicate with the NCS32100 through a master controller. The NCS32100 is connected to a fully functional PCB rotary sensor capable of sensing positions with an accuracy of <±50 arcsec. The board can be connected to a computer running the onsemi Strata Application, which provides a user interface for accessing position and velocity data, as well as a number of other auxiliary features that will be explained in this quick start guide.
Figure 1 depicts the NCS32100 Evaluation Board, showing the physical hardware. Figure 2 presents the NCS32100 Inductive Rotary Position Sensor Evaluation Board Block Diagram, illustrating the signal flow from master control circuitry to the NCS32100 application circuitry, including connections via USB, RS485, and internal regulators, linking to the PCB stator and rotor.
The NCS32100 evaluation board houses a full rotary sensor application with a master controller for accessing position and velocity data. Data is displayed through the onsemi Strata application (available for download from onsemi.com). The evaluation board is programmed, calibrated, and ready for demonstration. This quick start guide will explain how to connect the evaluation board for plug and play evaluation.
Features
| Feature | Description |
|---|---|
| NCS32100 IC | Interfaces with up to 8 inductive coils; Supports Low Power Battery Mode; Delivers Rotary position and velocity over a 2.5 MHz RS485 Bus. |
| RS-485 Interface | Connection between external master and NCS32100 is implemented with a 2.5 MHz RS-485 interface. |
| Adjustable Regulator for Battery Voltage Generation | Backup battery voltage to the NCS32100 can be adjusted with R350 (potentiometer) from 1 V to 5 V. Clockwise turn lowers VBAT voltage. |
| 40 mm PCB Inductive Position Sensor | Sensor portion of the board houses a PCB inductive sensor that uses a rotor and a stator. The rotor is mounted above the stator with a fixture designed to mount to standard motors. The rotor can be turned by hand in the absence of a mounted motor. |
| STM32 Master Controller | Evaluation board houses a master MCU that is programmed to communicate with the NCS32100 over the RS-485 interface. The STM32 MCU also communicates data to an external computer via a virtual Serial COM port. Application is plug and play with the onsemi Strata App. |
| Pre-Calibrated | Evaluation board has been configured and calibrated to work with the attached 40mm PCB rotary sensor. |
| Removable Master Module | NCS32100 IC and PCB sensor portion of the board can be snapped off for application evaluation. The master portion of the board can be replaced with a different system master. Interface protocol details are defined in the NCS32100 Reference Design Manual. |
Applications
Rotary Position Encoding
- Industrial Factory Automation
- Robotics Applications
- Precision Instrumentation
- Packaging
- Food and beverage
- Printing
- Textiles
- Mobile vehicle
- Aerospace
- Material Handling
- Lift Industry
- Automation
- Conveying
- Motor Feedback
Quick Start Procedure
- Download the onsemi Strata Application. The latest Strata release is available for download from www.onsemi.com/support/strata-developer-studio.
- Connect a computer running the onsemi Strata Application to the evaluation board (U17) using the provided USB cable. No other power supplies or bench equipment are needed. Figure 3 shows the NCS32100 Evaluation Board (Front), highlighting the PCB Rotor and Stator Fixture, RS-485 External Connection, VBAT Adjustment Potentiometer, Master Controller (STM32), and USB to PC Strata Application connector. Figure 4 shows the NCS32100 Evaluation Board (Back), indicating the Sensor Module / Master Controller Perforation and the NCS32100 IC.
- If the Strata App is not already running, start the application.
- Create a login. Figure 5 shows the Strata Login Window, a typical interface for user authentication.
The Strata Application will recognize the evaluation board connected via USB and bring up the evaluation board specific user interface. The evaluation board can be connected before or after the Strata App has been launched. Once the board is recognized, the NCS32100 Inductive Rotary Evaluation Board will be selectable in the list of Strata supported boards. Figure 6 shows the Strata UI Board Identification Bar, confirming the board connection. The user can update Strata settings to open the UI automatically upon connecting to the board if desired.
Figure 7 displays the NCS32100 Evaluation Strata UI. The user interface allows viewing current position and velocity in time plots, with current outputs shown at the bottom. The left side of the window provides user inputs for configuring the NCS32100, while the right side offers diagnostics.
Configuration Details
In the upper left side of the NCS32100 Strata UI, device configuration inputs are available. Three input boxes allow the user to set the low battery threshold, the over temperature threshold, and the resolutions for the velocity outputs. Gray text indicates the valid input range for each setting. Deleting an input does not reset it to default; users can restore defaults by inputting default values or power cycling the board.
Low Battery Threshold
This setting allows the user to choose a voltage at which a low battery error is reported. The input range is 1 V to 3.3 V. Setting this to 2.1 V, for example, will update the UI and turn the Low Battery LED red if the battery voltage drops below 2.1 V. The actual backup battery voltage can be adjusted using the blue R350 potentiometer; turning it clockwise lowers the VBAT voltage.
Over Temperature
This setting allows the user to choose a temperature threshold for the over temperature error, with a range of 0°C to 125°C. If the NCS32100's internal temperature exceeds this threshold, the Over Temperature LED will turn red.
Velocity Resolution
The NCS32100 outputs velocity as a 20-bit value. To mitigate noise floor effects on the least significant bits, the user can set the velocity resolution to a lower value (e.g., 16), which will zero out the last four LSBs of the velocity output.
Error Report
The lower left side of the NCS32100 Strata GUI displays indicators for system errors. Supported error indicators include:
Over Speed
The 'Over Speed' indicator turns red if the rotor velocity exceeds 6,000 rpm.
Sensor Error
The 'Sensor Error' indicator turns red if an open circuit in the sensor coils is detected. This is continuously monitored. Intentionally causing this error is not recommended as it may damage the PCB sensor.
Turn Count Overflow
The 'Turn Count Overflow' indicator turns red if the turns count crosses 0. This signals the master that a multi-turn count rollover needs to be handled.
Low Battery
The 'Low Battery' indicator turns red if the backup battery voltage falls below 2.7 V. This is distinct from the configurable low battery threshold. A recommended battery voltage is 3.3 V; 2.7 V indicates the battery needs replacement.
No Power
The 'No Power' indicator turns red if the 5 V VCC supply is removed from the NCS32100. This can be triggered by switching the red SW1 switch or, on revA boards, by pulling the J300 jumper.
Battery Alarm Threshold
The 'Battery Alarm Threshold' indicator turns red if the backup battery voltage falls below the user-defined battery threshold.
Over Temperature
The 'Over Temperature' indicator turns red if the user-defined temperature threshold is exceeded.
Any tripped error indicators can be reset to green by pressing the 'Reset Error' button on the right side of the Strata GUI.
Diagnostics
The right side of the NCS32100 Strata GUI displays encoder diagnostics:
Turns Count
This displays the number of full revolutions since power-up and can be reset to 0 via the 'Reset Turns' button.
Backup Battery Voltage
This output shows the current backup battery voltage as measured by the NCS32100, which varies with the R350 potentiometer setting (1 V to 5 V). The recommended voltage is 3.3 V.
Low Battery Threshold
This displays the user-specified battery threshold as read from the NCS32100, updating when the user changes the threshold.
Temperature
This displays the internal temperature of the NCS32100, which has an integrated temperature sensor. The evaluation board's lack of a standard grounding plane allows the internal temperature to be higher than ambient room temperature.
Max Temp.
This shows the NCS32100's readout of the user-specified over temperature threshold, updating when the threshold is changed.
Version #
Indicates the firmware version number currently running on the NCS32100.
Calibration
The NCS32100 Strata UI offers a self-calibration routine with two options, selectable via a dropdown menu. Figure 8 illustrates the Calibration Options. The 'Master' option uses the STM32 MCU for faster calibration (under 5 seconds), while the 'NCS32100' option uses the internal MCU (around 10 seconds) but requires no master support code. For calibration, the rotor must turn at less than 500 rpm. Clicking 'Calibrate' initiates the routine, pausing the UI until completion.
Resetting Controls
Resetting Position
The 'Reset Position' button allows the user to set the current rotor position as the 0 index for the encoder, establishing a new absolute reference for subsequent measurements.
Resetting Errors
The 'Reset Errors' button resets all error indicators back to a green status.
Battery Mode Evaluation
The NCS32100 supports evaluation of its low-power battery mode. In normal operation, it is supplied by 3.3–5 V on the VCC pin. If VCC is lost, the multi-turn count can be maintained via the backup battery pin connected to an adjustable regulator. VCC can be disconnected while the battery voltage remains supplied. Figure 9 shows the VBAT Adjustment Potentiometer and VCC Jumper. Disconnecting VCC via SW1 (or J300 jumper on revA) powers down the RS485 interface, preventing master communication, but the NCS32100 continues to track turns count. Re-installing the J300 jumper restores VCC and updates the master with the latest turns count.
Stand-alone Sensor Evaluation
The evaluation board is divided into two parts: the NCS32100 and PCB sensor module, and the master controller circuitry, separated by a perforation. Surface mount pads on the back of the NCS32100 module allow connection to an external master. Figure 10 describes this setup. Figure 11 shows the Encoder Module Portion of the Evaluation Board, detailing the VDDIO, GND, RS485-, RS485+, VCC, and VBAT pins. The complete NCS32100 module can be detached by snapping along the perforation. Wires can be soldered to the back pads for communication. The RS485 transceiver is on the module board and handles line drive for external cables. If the module is not detached, specific jumpers (J102, J2, J3, J1) must be removed for external master connection.
The NCS32100 evaluation board is designed for users to employ their own master controller or to communicate with a separated sensor module connected to a motor or system shaft. Figure 12 illustrates Rotor Fixture Dimensions, showing an 8 mm shaft diameter and mounting hole specifications.
Performance Considerations
The sensor module fixture supports motor mounts between 15 mm and 29 mm in radius. While the NCS32100 maintains accuracy up to 6,000 rpm and provides data at reduced accuracy up to 45,000 rpm, this evaluation board is not designed for speeds exceeding 2000 rpm. For higher speed evaluations, a specialized fixture is required. Users should also consider that materials used in the sensor module may expand/contract with temperature, impacting end applications.
Application Circuits
NCS32100 Application Circuit
Figure 13 shows the NCS32100 Connection Schematic for the evaluation board's sensor module. This circuit requires bypass capacitors on supply pins, an RS485 driver (if needed), and the PCB stator coils. The RJ1-RJ6 resistor network is for selecting excitation coil inductances and is not required for end-use applications. Refer to the NCS32100 Reference Design Manual for detailed application information.
NCS32100 Evaluation Board Master Circuitry
Figure 14 illustrates the Master Side RS-485 Transceiver and Level Shifters, and Figure 15 details the Master Controller MCU for Strata UI Interface. These schematics show the master controller circuitry used to communicate with the NCS32100 sensor module and the Strata UI. In a custom application, this circuitry would be replaced by the user's own master controller communicating via RS-485. Terminal block J303 allows connection of RS485, GND, VBAT, and VCC to an external cable.
Collateral Viewing
Clicking the "Platform Content" button in Strata provides access to system collateral upon release of the NCS32100. This includes:
- Evaluation Board Schematic
- Evaluation Board Layout
- Evaluation Board BOM
- Test Report
- Evaluation Board Users Guide
- Block Diagram
- Demo Setup
- Part Datasheets
- NCS32100 Reference Design Manual
Legal Information
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