GC9B72 Smartwatch Clock Kit

This kit turns a tiny computer and a round color screen into a watch that you program. By the end, your watch will:

• show the time with big, bright numbers or with an old-style clock face
• set its own clock by asking the internet what time it is
• show today's and tomorrow's weather, with little pictures of sun, clouds, rain, and snow
• work as a stopwatch that times laps, and as a countdown timer with an alarm
• switch between all of these with the press of a button

You will build it one small step at a time. There are 13 labs, numbered 00 to 12. Each lab is one program. Start at lab 00, and each lab teaches one new idea you will use in the labs after it.

What's in the Kit

Part	What it does
Raspberry Pi Pico 2 W	The brain of the watch. It's a microcontroller, a tiny computer on a board about the size of a stick of gum. The W means it has WiFi, so it can talk to the internet.
Round color display	The watch face. It is 2.1 inches across and has 360 × 360 tiny dots of light called pixels. A chip on the back called the GC9B72 turns the Pico's messages into pictures.
Three push buttons	How you control the watch. They are called MODE, UP, and DOWN.
Breadboard and wires	Connect everything without soldering.
USB cable	Gives the Pico power, and lets your computer send it programs.

How It Is Wired

The display has a row of 10 connection points along its bottom edge. Reading from left to right, they are labeled: GND VCC SCL SDA RST DC CS BL SDO TE. Only the first eight are used. Each one connects to a numbered pin on the Pico, like this:

Display pin	Pico pin	Wire color	What it carries
GND	GND	black	Ground, the "minus" side of the power
VCC	3V3	red	Power, 3.3 volts
SCL	GP2	orange	The clock beat that keeps the Pico and display in step
SDA	GP3	yellow	The data: the actual colors of the pixels
RST	GP4	green	Reset: tells the display to start fresh
DC	GP5	blue	Says whether the next data is a command or a picture
CS	GP6	purple	"Hey display, I'm talking to you!"
BL	GP7	gray	The backlight that makes the screen glow

Use 3V3, not 5 volts

The display's VCC wire must go to the Pico's 3V3 pin. The display is built for 3.3 volts, and 5 volts can damage it.

Each button has two legs. One leg goes to a Pico pin, and the other goes to GND:

Button	Pico pin	What it usually does
MODE	GP13	Changes what the watch is doing
UP	GP14	Makes a number go up, or starts something
DOWN	GP15	Makes a number go down, or resets something

Before You Start

You only need to do these steps once.

1. Put MicroPython on the Pico. MicroPython is the version of the Python language that runs on small boards like the Pico. Be sure to use the version for the Pico 2 W, which your teacher can find at micropython.org. The version for the plain Pico 2 has no WiFi.
2. Install Thonny. Thonny is the program you will use to write code and send it to the Pico.
3. Copy the kit's files onto the Pico. The labs need some helper files that live in a folder called lib on the Pico, and a settings file called config.py. Your teacher may have done this for you. If not, the kit folder has a script called upload-code.sh that copies everything at once.
4. Tell the watch about your WiFi. Copy the file secrets-template.py to a new file called secrets.py, and type in your WiFi network's name and password. Labs 04, 05, 09, and 12 use it. (secrets.py is kept private: it never gets shared online.)
5. Tell the watch your time zone. Open config.py and find TIMEZONE_HOURS. Use -5 for Eastern time, -6 for Central, -7 for Mountain, or -8 for Pacific.

The Labs

Click a picture to open that lab.

Lab		What you will do
00		Make a tiny light on the Pico blink, to check that everything works
01		Give the whole kit a checkup, like a doctor's visit
02		Say hello on the round screen
03		Show the time, day, and date
04		Ask the internet what time it is
05		Build a clock face with moving hands
06		Test the three buttons
07		Set the time with the buttons
08		Build a digital watch with giant numbers
09		Add the weather forecast
10		Make a stopwatch that times laps
11		Make a countdown timer with an alarm
12		Put it all together into one watch with five modes

Which program is running?

Every lab prints its name and version number in Thonny's shell when it starts, like 05-analog-watch-face.py v1.0. If the screen isn't doing what you expect, check that line first. It tells you which program the Pico is actually running.

Words to Know

Word	What it means
Pixel	One tiny dot of light on the screen. This screen has 360 × 360 = 129,600 of them.
Microcontroller	A small computer built to control one thing, like a watch, a toy, or a microwave.
Program	A list of instructions for a computer, written in a language like Python.
Loop	Part of a program that repeats over and over. A watch's program runs in a loop forever.
Variable	A name that holds a value, like second = 42.
Function	A named set of instructions you can use again and again, like draw_hand().
Module	A file of Python code that other programs can borrow from with import.
WiFi	A way for devices to connect to the internet without wires.

For Teachers

The Notes for Teachers page has the technical details: where the display driver came from, how fast the hardware really is, how each watch face avoids flicker, and a troubleshooting table. The screen pictures in these pages were made by running each lab's real code in a simulator of the display.