{"id":679,"date":"2017-02-06T20:01:00","date_gmt":"2017-02-07T01:01:00","guid":{"rendered":"http:\/\/sunapi386.ca\/wordpress\/?p=679"},"modified":"2023-02-07T17:27:23","modified_gmt":"2023-02-07T22:27:23","slug":"lessons-from-real-time-programming-class","status":"publish","type":"post","link":"https:\/\/sunapi386.ca\/wordpress\/lessons-from-real-time-programming-class\/","title":{"rendered":"Lessons from Real-Time Programming class"},"content":{"rendered":"\n

This post is about lessons I learnt in CS452 Real-Time Programming<\/a>, a 4th year undergraduate class at the University of Waterloo. Better known as \u201ctrains\u201d or \u201crealtime\u201d class.<\/p>\n\n\n\n

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\u201cEasy stuff! You play with trains all day (literally, maybe even night). All you need to do is write one simple program to control multiple trains so they don\u2019t crash!\u201d<\/p>\n\n\n\n

\u2014 chko on BirdCourses.com<\/a><\/p>\n<\/blockquote>\n\n\n\n

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The trains lab. Room 3018, 3rd floor Math & Computer building.<\/figcaption><\/figure>\n\n\n\n

The class is a bit unconventional because it indirectly teaches other topics, like time management and teamwork, by providing a large amount of work \u2014 so that you have to learn these skills. I\u2019ll talk about these lessons, hoping to address a more general audience.<\/p>\n\n\n\n

History<\/h1>\n\n\n\n

This class has been around since at least the 80\u2019s. Currently Bill Cowan<\/a> teaches this class, and has been for over 20 years.<\/p>\n\n\n\n

The equipment have evolved since then, but the underlying challenges have not.<\/em><\/p>\n\n\n\n

For example, teamwork, setting priorities, and dealing with real (imperfect) systems.<\/p>\n\n\n\n

\"\"\/
Prof. Bill Cowan explains the why sensor pickup sometimes have trouble detecting slow moving trains. The gap between the contact points may cause the pickup switch to flip twice.<\/figcaption><\/figure>\n\n\n\n

The early version of the QNX real-time operating system<\/a> took off from a pair of students taking this class, Gordon Bell and Dan Dodge. They decided to expand the class project into a full-fledged commercial RTOS<\/a> (real time operating system).<\/p>\n\n\n\n

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\u201cYou should try to find a partner for this class, it\u2019ll be hard without one. Generally I\u2019ve seen two outcomes:
(1) you become friends with your partner, or
(2) you stop being friends and hate each other.
I recommend not starting with a partner who is your friend, because you are already friends. Don\u2019t risk it.\u201d<\/p>\n\n\n\n

\u2014 Prof. Bill Cowan<\/p>\n<\/blockquote>\n\n\n\n

Curriculum<\/h2>\n\n\n\n

About 65% of the class involves building a small embedded kernel, with the other 35% working on the train management application.<\/p>\n\n\n\n

You can choose to program in whatever language you want, because there aren\u2019t any standard libraries provided. People generally program in C, because it\u2019s known as a systems language, and the programming examples given in class. But there\u2019s no reason why you can\u2019t do it in Rust language, for example \u2014 although godspeed, you\u2019re venturing into uncharted territory!<\/p>\n\n\n\n

The kernel runs on a TS-7200 embedded system<\/a>, and it talks to a M\u00e4rklin Train System<\/a> over RS232 type serial. The firmware is loaded on via RedBoot<\/a>, a bootstrap environment for embedded systems.<\/p>\n\n\n\n

\"\"\/
The M\u00e4rklin Train System<\/a>. You can see the center console where the RS232 is attached. Off to the right is the grey box that houses the TS-7200.<\/figcaption><\/figure>\n\n\n\n

The final exam is a take home 24 hour long exam, where you can use any resources you want, and you only need to do 3 of the 5 questions. The assignments and kernel make up 70% of the grade.<\/p>\n\n\n\n

Optional Technical Info<\/h2>\n\n\n\n

The microkernel did very little; it<\/p>\n\n\n\n