1. DesignDRIVE Position Manager SIN/COS
An overview of the C2000™ MCU SIN/COS solution
Brian Fortman
Industrial Drives and Factory Automation Marketing
C2000 Microcontrollers

2. DesignDRIVE Position Manager SIN/COS technology: Simplify the System
Reduce system cost by AND improve system performance
Features
Benefits
Integrated MCU solution for interface to SIN/COS transducers
Lowers system cost - no additional external sensing circuitry (sensor power supply and diff amps are still required)
Potentially lowers sensing latency (depending on existing architecture)
Supports high shaft speeds as well as high resolution at low speeds - 3 operating modes based on shaft speed
Optimum precision across a wide speed range
Error detection
Robust data integrity
Continuous calibration (at low speed)
Automatic correction of drift and offset errors
Delivers position and speed information
Tunable for each application
Tuned for position control applications (information obtained every control cycle)
Built for position and timing performance
Packaged library module
Easy to integrate and use
Available now!
Begin development today!
MCU
Dedicated
to SIN/COS

3. How does the DesignDRIVE SIN/COS solution work?
C2000™ MCU
ADC-B
ADC-A
C28x™
Core(s)
CMP
CMP
INDEX
QEP
Angle = arctan(A/B)
Speed = PulseCount
SinCos is a feedback methodology which is incorporated into encoder interfaces like Hiperface® as well as other proprietary interfaces.
ANIMATE
These so-called sinusoidal absolute encoders typically offer much higher position and speed resolutions than do resolver or incremental encoders. In conventional quadrature encoders, angle information is obtained by counting the edges of a pair of quadrature pulses. Angular resolution is fixed by the number of pulses per mechanical revolution. However, in SinCos transducers, precision of the angular measurement is increased by computing the angle between edges using the relationship between a pair of sine and cosine outputs from the sensor.
Effectively, an interpolation between edges is made to obtain a “fine” angle. The fine angle is computed using an arctangent of the two sinusoidal inputs. For this computation to be valid, both inputs must be sampled simultaneously. Typically, several thousand electrical revolutions of the sinusoidal signals occur during each mechanical revolution of the encoder shaft.
The internal analog sub-system of the F28379 Delfino MCUs is ideal for interfacing to SinCos transducers. The presence of multiple ADCs,
which can be triggered from the same source, allows simultaneous measurements of both input channels. In addition, the F28379 MCUs include a native ARCTAN instruction as part of the Trigonometry Math Unit (TMU) which means the angle calculation can be done in as little as 70 nanoseconds!
Another consideration is the high motor shaft speed state. In this case, there is no longer a need for precise angle information and the measurement algorithm only needs to count the number of complete sinusoidal revolutions to determine a “coarse” angle measurement. Typically, this is done using a pair of analog comparators
which compare the incoming sinusoids with a threshold representing the zero crossing point. The comparator outputs correspond to the sign of each sinusoid and the resulting digital signals are similar to those produced by a quadrature encoder. On the F28379 MCUs, there are up to eight pairs of analog comparators, each with its own programmable threshold voltage. These allow the quadrature pulses to be generated which are then fed internally to one of the on-chip quadrature encoder peripheral (QEP) modules
for coarse angle and speed measurements.

4. Position Manager SIN/COS solution
Check out TI Designs
TIDA-00176
TIDM-SERVODRIVE
System Block Diagram
SinCos solution supported on C2000 MCUs with dual ADCs, comparators and QEP
Software project is based on ‘F2837x
Requires buffer interfaces and transducer power supply circuits outside MCU
Interface circuits included on the DesignDRIVE Development Kit – IDDK
TMS320F2837x
SIN/COS Receiver
Simultaneously sampling ADC
Converts quadrature sinusoidal signals – low speeds
Comparators
Convert sinusoids to pulses – high speeds
Quadrature Encoder Pulse Module (QEP)
Counts high speed pulses and indicates direction
C28x CPU
Filtering, Calibration, Offset Correction, Gain Control
Fine angle calculation
Note that the ‘F28379D and ‘F28379S are the ‘Position-Manager-ready’ devices.
CLB Generates Clock To SPI So Only Data & CRC Information Is Clocked In.
Note: On POTENZA (F28004x) the CLB Will Also Perform CRC Calculations, Reducing CPU/CLA Processing Overhead.
Please refer to TIDA for a robust industrial-design power supply and interface circuit for EnDat. (EMI tested, etc.)

5. Position Manager solutions Development support
TMDXIDDK379D
Tools
Software
Installer Includes:
Libraries
Include Files
Example Projects and User’s Guides
License Agreement
Included in C2000 MCU controlSUITE
Documentation
(Included in download and on TI web)
E2E
Get help from the C2000 MCU Forum
e2e.ti.com/c2000
Docs, E2E, IDDK
Special Beta
Installer that includes:
PMEnDat22lib
Library User’s Guide
Conformance and performance test results
Example Project for IDDK to sensing from a Heidenhain EnDat encoder
Expected to work with most Heidenhain encoder
User’s Guide for the Example
Hardware interfacing considerations (connector to use, etc.)
List of specific encoders and the conditions by which the project was tested
Include files
License agreement

6. Get started today at

7. DesignDRIVE Position Manager SIN/COS solution
Thank You
DesignDRIVE Position Manager
SIN/COS solution