BenchChapter 3: Chains and rings

B08BREATHE

The task

Make CH1 breathe: a triangle from 0 up to 5 volts and back down, over and over.

Move the duty on P0 by 10 percent on each tick of P1, up to 100 and back down to 0.

The chip's ports, each with its kind and the parts its signal reaches. Cyan reads, lemon writes.

Two loops: one climbs until the duty reaches 100, the other falls until it reaches 0.

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

Hint 1Show

B can hold the duty between ticks.

Hint 2Show

JNZ falls through when A is 0, which ends the falling loop by itself.

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

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

u1SC-2 standard

UP: IN P1
MOV A, B
ADD 10
MOV B, A
OUT P0
SUB 100
JNZ UP
DN: IN P1
MOV A, B
SUB 10
MOV B, A
OUT P0
JNZ DN

A second program that also passes, and matches par on every benchmark.

The falling loop adds a negative step and runs while the duty is above 0.

u1SC-2 standard

UP: IN P1
MOV A, B
ADD 10
MOV B, A
OUT P0
SUB 100
JNZ UP
DN: IN P1
MOV A, B
ADD -10
MOV B, A
OUT P0
JG DN