1. Developing Hardware Control Systems with.NET Christopher Chess Ellsworth cce@cs.appstate.edu http://www.cs.appstate.edu/~cce/

2. Outline Hardware Overview Telescope Control Hardware Software / Hardware Interface Software Systems Design

3. Outline Hardware Overview Telescope Control Hardware Software / Hardware Interface Software Systems Design

4. Controlling Devices Parallel digital I/O Counter/Timer Devices Serial communication Embedded RF

5. Parallel Digital I/O Control the logical state of individual pins Pins can often be written to or read from on the bit, byte, short, or word level

6. Counter-Timers Measure time related quantities Generate pulses and pulse trains Counting events Pulse and frequency measurement

7. Quadrature Counters Measures two signal edge separation events Used for monitoring shaft rotation position and direction Can be directly connected to off the shelf position encoders

8. Serial Communications Asynchronous vs. Synchronous Synchronous requires a separate clock signal RS232 vs. TTL level asynchronous serial I/O TTL level: 5V, true logic RS232: ±12V, inverted logic These standards are sometimes abused by hardware manufacturers (i.e. 5V, inverted logic) A hardware UART is generally TTL level and is connected to a level shifter which inverts the logic and changes the voltage from 5V to ±12V Some other common serial standards: SPI I 2 C

9. Serial Communications The TTL level (5V) and RS232 (±12V, inverted logic) signals produced by bytes being sent through a 8N1 connection.

10. Embedded RF Devices Are often “self contained” and have a serial interface Some have transparent modes where bytes that are written to one module come out of the other module and visa versa (no exposed datagram) This allows any system that supports serial I/O to be extended to RF AeroComm, Inc.AeroComm, Inc. manufactures a variety of inexpensive/high quality RF modules for OEM’s MouserMouser is the only distributor for AeroComm that sells individual units, although developers kits are available directly from AeroComm

11. Outline Hardware Overview Telescope Control Hardware Software / Hardware Interface Software Systems Design

12. Hardware on the Telescope Stepper motors for driving the RA and DEC axes Optical shaft encoders for detecting telescope position Hand paddle for moving the telescope North, East, South, West, and high speed mode

13. Telescope Control Hardware Our system uses 3 Measurement Computing PCI boards: PCI-DIO-24 (datasheet)datasheet Contains one 82C55 digital I/O chip with 24 bidirectional I/O pins82C55 I/O is CMOS TTL level PCI-CTR05 (datasheet)datasheet Based on the 9513 counter/timer device9513 Has five independent 16-bit counters PCI-QUAD04 (datasheet)datasheet Has 2 LS7266R1 24-bit Dual-Axis Quadrature Counter ICsLS7266R1

14. PCI-DIO24 Based on the 82C55 digital I/O chip82C55 The 82C55 has three I/O ports:82C55 Port B (input) Paddle buttons: N, E, S, W, 1x4x Speed Mode Port C (output) RA Motor Direction RA Motor Speed Mode 1x4x DEC Motor Direction DEC Motor Speed Mode 1x4x

15. PCI-DIO24

16. PCI-CTR05 Based on the 9513 Counter/Timer IC9513 Generates pulse trains for RA and Dec stepper motors Stepper motors move 1 step per pulse and have 500 steps per revolution

17. PCI-CTR05

18. PCI-QUAD04 Based on two LS7266R1 24-bit Dual-Axis Quadrature Counter ICsLS7266R1 Connected to optical shaft encoders on the RA and Dec axes Used for telescope position detection

19. PCI-QUAD04

20. Outline Hardware Overview Telescope Control Hardware Software / Hardware Interface Software Systems Design

21. Software / Hardware Interface Interface Options: Directly write to registers through the PCI bus Use Universal Library API if using Measurement Computing hardware Other vendor API’s

22. Universal Library API for.NET A set of CLR classes and enumerated types for controlling Measurement Computing boardsMeasurement Computing Good API documentation and over 100 example applicationsAPI documentation May work with boards from other vendors (National Instruments, Keithley, etc)National InstrumentsKeithley

23. Universal Library API

24. Outline Hardware Overview Telescope Control Hardware Software / Hardware Interface Software Systems Design

25. Software Design Need to design a system that does not depend on any specific board Should have layers of abstraction between the hardware control and program logic

26. Software Model

27. Example Implementation

30. Testing Note Make a test harness that will allow for easy testing This could be connected to a frequency generator/counter and a breadboard with buttons and lights Another option is to connect it to another computer which would simulate whatever hardware the system is to control

31. Manufactures and Distributors Test, measurement, and automation equipment Measurement Computing National Instruments Keithey Microcontrollers and ICs Parallax Microchip Technology Inc. AeroComm RF Modules Electronic components Mouser DigiKey Jameco Hardware Stock Drive

32. Questions? Feel free to email me if you have any questions cce@cs.appstate.edu