PYTHON · NUMPY

What the wire carries

Read a real sensor value off a two-wire bus and route it into a decision -- the connector layer, in code.

01Challenge

A distance sensor sits on the I2C bus -- the same two-wire bus that Qwiic and STEMMA-QT connectors ride. Each reading arrives as two bytes: a high byte and a low byte of one 16-bit millimetre value. The starter decode() ignores the high byte, so the numbers are wrong. Combine the bytes, then route the reading into an ACT decision: brake when something is closer than 250 mm.

02Model

Solderless connectors do not carry meaning -- they carry a bus. Qwiic and STEMMA-QT are the same I2C bus with different plugs; Grove can carry I2C or a serial line. A sensor speaks in registers of bytes, and reading it is combining those bytes into a number your think() block can use.

03Guided practice

Step A (worked): decode returns just the low byte, so 0x0300 reads as 0 and 0x012C reads as 44 -- run it and see the wrong distances. Step B (the fix): shift the high byte up and OR in the low byte: (hi << 8) | lo, so the reads become 300, 200, 1000, 30 mm. Step C (route it): the brake rule fires only for readings under 250 mm -- 200 and 30. Step D: PASS when the decode and the braking both match.

04Feedback

PASS WHEN PASS when the two bytes decode to 300, 200, 1000, 30 mm and the brake decisions match.

If your run fails, check:

Read the bench’s printed result — it passes when the two bytes decode to 300, 200, 1000, 30 mm and the brake decisions match. Run the cells top to bottom; if one errors, the FAIL line names the step to fix.
The high byte is still being dropped -- shift it in with (hi << 8) | lo.

05Retrieve & space

Qwiic and STEMMA-QT ride which bus?
Why can't the four-pin I2C bus carry a camera?
How do you turn a high byte and a low byte into one 16-bit value?

06Mastery & project

Pass the lab: the sensor's two bytes decode to real millimetres and drive a braking decision. You have read the connector layer -- a bus of bytes -- in code.

The connector reference in full -- Qwiic, Grove, LEGO, magnetic, EPM, and what each carries -- lives on the Connection Systems map, with every kit a node in the Maker Atlas.

GO FURTHER · THE LIVE PLAYGROUND

The connector families, mapped ↗ — which connector rides which bus, and the physical-AI-ready rubric.

← The loop you can hold The graph is a policy →

PYTHON · NUMPY

What the wire carries

Read a real sensor value off a two-wire bus and route it into a decision -- the connector layer, in code.

You read

the arrays and values already in scope

You change

the code you write in each cell

Fixed

the dataset and the checks that grade you