Design Your Own Emotion

This is the capstone, and it is the only lab that does not tell you what to draw. You are going to invent expressions nobody in this kit has drawn before, and then find out whether a stranger can read them.

That last part is the real test. A robot face is not art you look at — it is a message you send. If the person standing next to your robot cannot tell proud from confused, the expression does not work yet, no matter how good it looks to you.

This is the superpower, in your hands

Communicating a feeling that lands correctly in somebody else's head is the whole thing this kit has been building toward. Let's draw some feelings — yours this time.

Use All Four Habits

Habit	What it means here
Decomposition	Break the feeling into eyes, eyebrows, and mouth, and decide what each part does before you code
Pattern recognition	Add a row to the table — do not write a new function, because you already know it would look like all the others
Abstraction	Build only from face.py's parts, so your emotion inherits every fix the module ever gets
Debugging	When it does not read right, change ONE number, look, and change one more

Step 1: Write the Brief in Words First

Fill this in before you touch a single number:

My emotion is: ................ (proud? confused? shy? suspicious?)
The eyes are:  ................ (wide? narrow? looking away?)
The eyebrows:  ................ (raised? one up? angled down?)
The mouth is:  ................ (smile? flat? open? off to one side?)
The closest emotion it might be confused with is: ................
and I will keep them apart by: ................

Writing that down first is not busywork. It is the decomposition step, and skipping it is why most first attempts read as "generic robot."

Step 2: Turn Each Line Into a Number

#            name    eye_rx eye_ry brow_L brow_R lift  mouth        x   y  color
MY_EMOTIONS = [
    ("Proud",        36,    29,    0,     0,    11,  face.SMILE,  57, 21,
     config.color565(255, 200, 90)),

    # TODO: your first emotion. Start by copying the row above and
    # changing ONE column at a time, looking after each change.

    # TODO: your second emotion. Make it one that could be confused with
    # your first, then push them apart until a tester can tell them apart.
]

One row is filled in as a worked example. Study it before you replace it: "Proud" is a small confident smile with the brows lifted and the eyes relaxed — pleased, but not surprised.

Every number in that table is a pixel number, and it belongs to this 360×360 panel and nothing else. The smartwatch kit runs the same table on a 240 px screen with every figure scaled down by two-thirds — its eye_rx ceiling is 34, not 51. If you ever borrow a row from that kit, scale it first; if you lend one to it, say which screen it was designed for.

Column	Range that works	Note
eye_rx / eye_ry	Keep eye_rx under about 51	Wider and the eyes start disappearing under the bezel
brow_L / brow_R	roughly −18 to 18	Two different values give you a skeptical, lopsided brow
lift	roughly −10 to 27	A big lift reads as surprise
mouth style	SMILE, FROWN, FLAT, OPEN, SMIRK, SNEER
color	config.color565(r, g, b)	Pick this last — see below
name (stage 3 reveal)	12 characters or fewer	face.label() draws in this kit's bigger 16×32 font, so a name eats twice the vertical band it did on the smartwatch kit's smaller one

That last row is worth pausing on. Every Ekman emotion name still fits under 12 characters — but the ceiling itself is new, and it exists because of the label font, not because of anything about your design.

Pick the Color Last

Step 3 tests whether the color helped, and you cannot answer that question if the color was there from the start — you will have been tuning both at once and will not know which one is doing the work.

Step 3: Run the Readability Test as a Controlled Experiment

Every face gets shown to your tester in three stages, and button A moves to the next one:

Stage	What they see	What you ask
1. Shape only	The face in plain white, no label	"What is the robot feeling?" — write down their exact word
2. With color	The same face, same shapes, in your color, no label	Ask again; write that word down too
3. Reveal	The name you intended	Nothing — just show them

Only one thing changed between stage 1 and stage 2, which is what makes this an experiment instead of a demo. Three outcomes are possible, and all three teach you something:

Outcome	What it means
The word got closer to what you intended	Color reinforced a shape that was already nearly right. This is the win, and it is real.
The word did not change	Your shapes were carrying the meaning alone. Keep the color if you like it — but know it is decoration here, not communication.
The word got worse, or they hesitated	Usually the color is too dark to read across the room, or it is fighting the expression. Fix the shape first.

Test at least three people. If two of them say something you did not intend at stage 1, the expression needs work — and their wrong word is your best clue about which feature is misleading them. Do not reach for color to paper over it.

Here's the worked example at stage 1, shape only:

A Round Screen Helps You Here

With no corners and no rectangular frame, there is nothing in the picture except the face. Whatever your tester reads, they read from the expression alone — no border, no background, no visual furniture to lean on.

This panel also gives you an edge the smartwatch kit doesn't have. At 360×360 you have 129,600 pixels describing the picture, against the smartwatch kit's 57,600 — 2.25 times as many pixels tracing every curve. A subtle eyebrow angle that turned into a jagged staircase on the smaller screen can survive intact here. Use the extra resolution, but keep testing from across the room, not from arm's length — that's the distance your finished robot will actually be read from.

Step 4: The Checklist

Check your work against this before calling it finished:

Check	Done?
I wrote the design brief in words before coding
Each emotion is ONE row of data, not a function
I used only face.py parts, no raw shapes calls
Every part of the face is inside the circle
My emotion names are 12 characters or fewer
Three testers named the emotion at stage 1, with no color at all
I can say which single feature carries the meaning
It still reads correctly from across the room
My color has enough green in it to stay bright
The emotion still reads for a color-blind tester

The "inside the circle" check has a tool, so use it instead of squinting: config.inside_circle(x, y) is true for any point within config.SAFE_RADIUS of the middle. Check the outer edge of each eye and both ends of the mouth — those are the points a big number pushes toward the bezel first.

Those last two rows are engineering rules, not decoration rules. Your eye takes most of its sense of brightness from green light and almost none from blue, so a face in pure blue is a dark face however vivid the number looks in the code — see Color and Bits for the arithmetic. And roughly one boy in twelve has a red-green color deficiency — if red means angry and green means happy on your robot, it says nothing at all to somebody in most classrooms.

The fix is free: make the shape carry the meaning and let the color agree with it. If your face passed stage 1, you already did this.

Where to Take It Next

• Keyframes — give your emotion an entrance animation. A feeling that arrives over 300 ms reads far more alive than one that snaps on, and Only Redraw What Changed is what makes that animation smooth on a display with no frame buffer.
• A Face With a Memory — add it as a state, so the robot can arrive at your emotion on its own instead of waiting for a button.
• Standalone main.py — rename your finished program main.py and the robot wears your expression the moment it gets power, with no computer attached.

Look what you built

You started this kit by blinking an LED. You are finishing it with a robot that has a face of your own design on a real 2.1" round display, a personality with a memory, and opinions about being poked — and every part of it is something you can explain, measure, and fix. That is the superpower. Go build something with it.

References

• The Emotion Table — the column format your rows use
• The Face Module — the parts you are building from
• Live Face Parameters — the fastest way to find the numbers you want
• Design Your Own Emotion on the 1.2" kit — the same lab on the smaller 240×240 screen, where the numbers are two-thirds of these