BenchChapter 4: Stars and hubs

B22FOLLOWER

The task

V1 sends a square wave through R1 into C1, so its edges reach P0 slowly.

P0 reads 1 once CH1 climbs past 3 volts, and 0 once it falls under 1.5 volts.

Copy P0 to the LED on P1, so the LED follows what the chip reads.

The board

The chip's ports, each with its kind and the parts its signal reaches. Cyan reads, lemon writes. On a narrow screen, scroll the board sideways to see all of it.

Sources: V1 5 V square at 50 Hz
Resistors: R1 3.3 kΩ and R2 330 Ω
Capacitors: C1 1 µF
LEDs: D1 green
Probes: CH1 and CH2

Key idea

IN P0 puts the reading in A. OUT P1 writes A to the LED.

Hints

Each hint goes a step further than the one before. Open them one at a time.

Hint 1Show

A program loops by itself: after its last line it starts again from the first.

Hint 2Show

The LED lags behind V1. That delay comes from C1, not from your program.

Solution

Reveal the Full SolutionThe complete program for FOLLOWER. Open it only when you want the answer.

The reference program

The game's own solution. It passes every test and scores exactly par on every benchmark.

The LED copies what P0 reads.

u1SC-2 standard

IN P0
OUT P1

CYCLES: 600; at par
ENERGY: 1200; at par
NODES: 1; at par
INSTRUCTIONS: 2; at par