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docs/assignments/week11-machines/tic-tac-toe-machine.md

 # Tic Tac Toe Machine
 
-
 <video width="600" height="400" controls>
   <source src="../tic-tac-toe-machine/tic-tac-dog-ad.m4v" type="video/mp4">
 </video>
 
-# Iteration 1
+## This week's objectives
+
+- Mechanical Design
+    - design a machine that includes mechanism+actuation+automation+application ✅
+    - build the mechanical parts and operate it manually ✅
+- Machine Design
+    - actuate and automate your machine ✅
+- Document
+  the [group project](/2022/labs/barcelona/students/barcelona-group-assignment/assignments/week11-machines/tic-tac-toe-machine/)
+  and your individual contribution ([this page!](#)) ✅
+
+## Machine
+
+![](tic-tac-toe-machine/machine-drawing.jpg)
+
+### Application
+
+> [Application](https://en.wikipedia.org/wiki/Application) a device designed to help the user to perform specific tasks
+
+The application for our machine is to play tic-tac-toe against a human adversary, using an aggressive play-to-win AI.
+
+### Automation
+
+> [Automation](https://en.wikipedia.org/wiki/Automation) describes a wide range of technologies that reduce human intervention in processes.
+
+Our machine provides full end-to-end automation for the entire game of tic-tac-toe.
+
+![](tic-tac-toe-machine/component-diagram-plain.png)
+
+### Actuation
+
+> [Actuation](https://en.wikipedia.org/wiki/Actuator). An actuator is a component of a machine
+> that is responsible for moving and controlling a mechanism or system, for example by opening a
+> valve. In simple terms, it is a "mover".
+
+From the point of view of machine design, **Actuators** are the parts of the machine that operate in its environments (
+to affect it/change it, in some way), while the **sensors** are the parts that receive information from its environment.
+
+In terms of actuation, our machine has a moving pen, whose tip can be arbitrarily positioned in any position in the
+operating space/volume.
+
+For all intents and purposes, however the pen will only occupy 2 planes in space:
+
+- the _**paper**_ plane: when the tip of the pen is touching the surface below the machine. This setting can be used to
+  paint, draw on it or mark it in some way.
+- the _**hover**_ plane: when the tip of the pen is held away from the floor/paper/whiteboard. This position allows us
+  to freely move the pen without leaving marks or painting anything.
+
+### Mechanism
+
+> [Mechanism](https://en.wikipedia.org/wiki/Mechanism_(engineering)) (engineering), rigid bodies connected by joints in order to accomplish a desired force and/or motion transmission
+
+The machine that we have built has various mechanisms to operate and perform action in all 3 spacial dimensions:
+
+- 1 mechanism to operate on the X axis (1 degree of freedom) using dual stepper motors
+- 1 mechanism to operate on the Y axis (1 degree of freedom) using a single stepper motor
+- 1 mechanism to operate on the Z axis (1 degree of freedom) using a single servo motor
+
+The combination of these mechanisms allow the machine to have an operating space/volume of approx:
+
+[//]: # (TODO calculate operating space)
+
+> XXX mm x YYY mm x ZZZ mm = XYZXYZ mm<sup>3</sup>
+
+Here's a short excerpt of the code used to control the machine over the operating space.
+
+## Problems encountered
+
+### During mechanical design and assembly
+
+TO DO
+
+### During electronics design and implementation
+
+TO DO
+
+### During software programming
+
+#### GRBL and Relative coordinates
+
+During our initial iterations, we were having issues when we tried to get the steppers to draw figures on our board, but
+not when we were trying to move around the board (hovering).
+
+Our initial hypothesis was that maybe GRBL did not support relative coordinates.
+
+1. After a bit of research we came across specific
+   documentation [(Pg. 3) for GRBL 1.1.2](https://www.cnc4fun.com/wp-content/uploads/2019/12/Grbl-Commands-v1.1-2.pdf)
+   that clearly indicates that it supports G91 for relative positioning.
+2. Something else I learned is that "Relative positioning" is
+   called "[Incremental](https://www.sainsmart.com/blogs/news/grbl-v1-1-quick-reference)" in some environments. This
+   proved useful when googling around, as we found many more hits and useful results.
+3. A third thing I learned is that there is
+   specific [syntax that allows relative coordinates to be used while GRBL is in absolute mode.](https://www.cnccookbook.com/g91-g90-g-code-cnc-absolute-incremental-programming/)
+   This syntax uses UVW Commands instead of XYZ, although it seems to be unsupported by GRBL 1.1.
+
+This avenue of research did not help us resolve the issue we were having, and at the end, the problem was fixed by
+re-tightening all the belts used by the steppers, and doing a soft reset of the shield.
+
+#### We accidentally burned one arduino board
+
+So, full disclosure... We don't actually know what happened, but we believe it burned/died because it is no longer
+working in any capacity.
+
+Context: While we were using an Arduino UNO Board, it suddenly stopped working. In front of all of us. And no one was
+moving around/touching it.
+
+That's not the worst part. The worst part is that we have not been able to find out the root cause of this unexpected
+event.
+
+Everything worked as normal when we place a new arduino board and reloaded the GRBL config settings, so it's clearly
+something wrong with the Arduino UNO board, and trying to flash it with the GRBL firmware/library was not possible once
+it died.
+
+We need to do a bit more research to figure out what happened! A 20$ damage is a huge piece of the budget. We better
+find answers.
+
+#### Desperation to fix a GRBL problem almost ended with my laptop infected with suspicious virus
+
+Pro Tip: when developing for GRBL/Arduino, on a Linux machine, with custom software, always click on any "Download
+Windows Registry Fix.exe" links that may appear in front of you!
+
+![](tic-tac-toe-machine/mega-virus.png)
+
+😒 Don't trust all links!
+
+#### Inconsistent command execution & GRBL randomly dropping instructions without errors
+
+Alright! So this was one of the most confusing problems, and one of the most celebrated once it got fixed.
+
+Imagine that Arduino is receiving commands correctly when you send them via the Arduino IDE / Serial Monitor:
+
+![](http://diyprojects.eu/wp-content/uploads/2015/05/arduino-cnc-shield-grbl-v0.9i-serial-monitor-welcome.png)
+
+But that the exact same commands **Sometimes** fail when you send them via your custom program:
+
+![](tic-tac-toe-machine/serialwrite-fails.png)
+
+This problem has all ingredients for the perfect frustration 🥴🤯 storm 🌩:
+
+1. The command (any command!) works perfectly on a known platform (Arduino IDE): so it's not hardware issue
+2. We tested different cables: so it's not a comms issue
+3. It works sometimes correctly from our program: so it's not an obvious error in our code/library
+4. All the examples we are finding online have code that looks extremely similar to our custom code (open port,
+   handshake, etc...): so we have not missed anything obvious
+5. What is it?!
+  1. The answer came to us after a quick question to one of our local instructors (Thanks Josep! 💝):
+    1. It turns out, we had forgotten to send out the "new line" character at the end of our command.
+    2. The new line command is normally generated when we press `Return` or `Enter` key on our keyboards.
+    3. The same key we press on the Arduino Serial Monitor to "send" the command.
+
+The fix was easy and swift: We just had to add a `\n` new line character at the end of each command we wanted to
+send `arduino.serialWrite(command);` for a `arduino.serialWrite(command + "\n");`
+
+It was so obvious, and yet so invisible, until it got fixed.
+
+✨ [What a difference 1 byte makes](https://youtu.be/OmBxVfQTuvI?t=15)✨, when implementing low-level protocols!
+
+Life lesson:
+
+- Sometimes you might be in a pit of darkness and divine bliss is just 2 minutes away from you.
+- Ask for help sooner: We should have asked for help sooner! After the 1st hour of research, I already had enough
+  answers to ask fully-informed questions. The determination to trying to figure it out without bothering others did not
+  prove particularly useful.
+
+--------
+
+## Development Iterations
+
+### Iteration 1
 
 Sending custom commands to arduino via Serial Interface
 
@@ -13,6 +180,8 @@ Sending custom commands to arduino via Serial Interface
   <source src="../tic-tac-toe-machine/iteration-1-sending-custom-commands-to-arduino-via-serial.m4v" type="video/mp4">
 </video>
 
-# Iteration 2
+### Iteration 2
+
+Sending GCODE commands to Arduino with GRBL installed
+
 
-Sending GCODE commands to Arduino with GRBL installed
\ No newline at end of file