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

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

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.

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-00172 for a robust industrial-design power supply and interface circuit for EnDat. (EMI tested, etc.) http://www.ti.com/tool/tida-00172

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 Email https://txn.box.com/s/nxmpe1ea1m27cei542lk75m4r516j242 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

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