Pisco Code encodes decimal, hexadecimal, or binary values as LED blink patterns using a single status LED. No serial port or display needed.

This is the Arduino-compatible distribution of the Pisco Code library. It is automatically generated from the main repository on each release.

⚠️ Requires C++17 — Works out of the box with ESP32, RP2040 (Pico), STM32, SAMD, ESP8266 and other boards whose toolchain defaults to C++17.
Other boards (e.g. Arduino AVR) can be used by enabling C++17 manually — see Enabling C++17 on older boards below.

1. Open Arduino IDE
2. Go to Sketch → Include Library → Manage Libraries…
3. Search for Pisco-Code
4. Click Install

1. Download the latest release .zip from Releases
2. In Arduino IDE: Sketch → Include Library → Add .ZIP Library…

#include <Pisco-Code.h>

bool ledOnboard(pisco_code::LedControlCode code)
{
    switch (code)
    {
        case pisco_code::LedControlCode::ON:
            digitalWrite(LED_BUILTIN, HIGH);
            return true;
        case pisco_code::LedControlCode::OFF:
            digitalWrite(LED_BUILTIN, LOW);
            return true;
        default:
            return false;
    }
}

pisco_code::LedControllerSoftwarePwm controller(ledOnboard);
pisco_code::SignalEmitter             emitter(controller);

void setup()
{
    pinMode(LED_BUILTIN, OUTPUT);
    emitter.showCode(
        pisco_code::SignalCode{103},
        pisco_code::Radix::DEC,
        pisco_code::NumDigits{0});
}

void loop()
{
    emitter.loop();
    delay(1);
}

Most embedded projects lack a convenient way to observe internal variables — serial ports, debuggers, or displays aren't always available. Pisco Code solves this by encoding values as LED blink patterns that anyone can read by eye.

A common approach is to blink an LED n times to represent the value n. For multi-digit numbers like 312, you blink 3 times, pause, 1 time, pause, 2 times:

This works — but breaks down for zeros (how do you blink 0 times?) and can be hard to follow.

Pisco Code adds a framing signal — a dim glow before each digit sequence begins. This makes every digit unambiguous, including zero:

Code 121:

Code 120 (with a zero digit):

Minimum digits (e.g. 002 for 0.02 V sensor reading):

Negative values (-12 — long blink prefix):

Pisco Code has been used in the Pisco de Luz project since 2020, reading battery voltage, solar panel output, temperature, and usage hours in off-grid solar lighting systems — all through a single LED.

For full documentation, architecture details, and cross-platform support (AVR, STM32, native), see the main repository.

Some boards (e.g. Arduino AVR — Uno, Mega, Nano) ship with a toolchain that defaults to C++11. You can switch to C++17 by creating a platform.local.txt file:

1. Find your board's platform.txt. Common locations:

   OS	Path
   Windows	%LOCALAPPDATA%\Arduino15\packages\arduino\hardware\avr\<version>\
   macOS	~/Library/Arduino15/packages/arduino/hardware/avr/<version>/
   Linux	~/.arduino15/packages/arduino/hardware/avr/<version>/

2. In that same folder, create a new file called platform.local.txt with the following line:

   compiler.cpp.extra_flags=-std=gnu++17
   

3. Restart the Arduino IDE and recompile.

Note: platform.local.txt overrides settings without modifying the original platform.txt, so board-manager updates won't undo your change.

See the Changelog in the main repository.

MIT — see LICENSE.