BenchChapter 3: Chains and rings

B07BAR GRAPH

The task

P0 is an analog input: IN P0 reads its voltage as a percent of the 5 volt supply.

Light an LED for each quarter of the supply the input reaches:

P1 from 25 percent, P2 from 50, and P3 from 75.

Sample the input on each tick of P4.

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 2.5 V and V2 2.5 V triangle at 50 Hz
Resistors: R1 330 Ω, R2 330 Ω, and R3 330 Ω
LEDs: D1 green, D2 yellow, and D3 red
Probes: CH1, CH2, CH3, and CH4

Key idea

DIV 25 turns the reading into the number of quarters it has reached.

Hints

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

Hint 1Show

A digital output is on for any value but 0, so a quotient of 1 or more lights an LED.

Hint 2Show

CH1 is the input; CH2 to CH4 are the LEDs.

Solution

Reveal the Full SolutionThe complete program for BAR GRAPH. 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.

u1SC-2 standard

IN P4
IN P0
MOV B, A
DIV 25
OUT P1
MOV A, B
DIV 50
OUT P2
MOV A, B
DIV 75
OUT P3

CYCLES: 210; at par
ENERGY: 420; at par
NODES: 1; at par
INSTRUCTIONS: 11; at par

Another way: Quarters

A second program that also passes, and beats par on CYCLES, ENERGY, and INSTRUCTIONS.

One division: the quarters, then halves and thirds of the quarters.

u1SC-2 standard

IN P4
IN P0
DIV 25
OUT P1
MOV B, A
DIV 2
OUT P2
MOV A, B
DIV 3
OUT P3

CYCLES: 191; under par
ENERGY: 382; under par
NODES: 1; at par
INSTRUCTIONS: 10; under par