Chapter 10: Finite State Machines
Embedded
Systems - Shape
The World
Jonathan
Valvano
and Ramesh Yerraballi
As part of the edX online class, we made some interactive web pages to illustrate fundamental concepts
| 2. Fundamental Concepts | Number conversions |
| 5. Introduction to C | Flowcharts, C vs assembly |
| 6. Microcontroller Ports | Input/output, direction register |
| 7. Design and Development | Successive refinement, if-then, loops |
| 10. Finite State Machines | Vending machine and stepper motor |
| 11. UART Serial Interface | Blind, busy-wait, interrupt, serial port |
| 12. Interrupts | Mail box, context switch |
| 13. DAC and Sound | Sampling rate, precision, how a DAC works |
| 14. ADC and Data Acquisition | How an ADC works, Nyquist Theorem |
A simulation of a Vending machine dispensing soda with the corresponding FSM state changes
Click 'CW' or 'CCW' to step the motor clockwise and counterclockwise, respectively. Observe how different microcontroller outputs to the motor coils produce different responses from the motor. Assume that an output value of '1' to a motor coil will cause current to flow in that motor, resulting in a 'N' oriented magnetic field at that coil.
Questions:
What is the output sequence that produces one complete counterclockwise
rotation in the motor?
What is the output sequence that results in one complete clockwise
rotation in the motor?
Identify two sets of output values in the sequence that will never
occur one after the other.
How can you implement a stepper motor with a finite state machine? Draw
the complete state graph with all transition arrows.
Reprinted with approval from Embedded Systems: Introduction to ARM Cortex-M Microcontrollers, 2016, ISBN: 978-1477508992, http://users.ece.utexas.edu/~valvano/arm/outline1.htm
and from Embedded Systems: Real-Time Interfacing to Arm® Cortex™-M Microcontrollers, 2016, ISBN: 978-1463590154, http://users.ece.utexas.edu/~valvano/arm/outline.htm