Enable Pin Buffers

Instead of pushing data continuously over the serial port, your MCU can store sensor readings locally in a ring buffer. The mcpu-client will automatically calculate when the buffer is about to fill up and poll the data just in time.

Firmware Configuration

To enable buffering for a standard pin (like an ADC sensor), you need to define its capabilities and sampling rate when setting up the pin registry in your main.cpp.

#include <MCP-U.h>

McpDevice mcp("sensor-node", "1.0.0");

void setup() {
  Serial.begin(115200);

  // Example: Setting up an ADC pin with a buffer
  // Pin 34, Name, Type, Description
  McpPin& mySensor = mcp.add_pin(34, "voltage_sensor", "adc", "Main voltage monitor");

  // Enable the buffer capability
  mySensor.capabilities.buffer = true;

  // Configure the sampling rate and buffer size
  // The MCU will sample every 100ms and store up to 50 samples locally.
  mySensor.sampling.interval_ms = 100;
  mySensor.sampling.buffer_size = 50;

  mcp.begin(Serial, 115200);
}

void loop() {
  // Your sampling logic goes here
  // You must push values to the pin's buffer at the specified interval
  static unsigned long lastSample = 0;
  if (millis() - lastSample >= 100) {
    lastSample = millis();
    int val = analogRead(34);
    mcp.push_pin_buffer(34, val); // Hypothetical API for illustration
  }

  mcp.loop();
}

How the Client Reacts

When the mcpu-client connects, it reads this metadata.

1. It calculates the buffer capacity: 50 samples * 100ms = 5000ms (5 seconds).
2. It sets a polling timer at 75% capacity (every 3.75 seconds).
3. It calls get_pin_buffer to extract the array of values.
4. It parses the array, infers timestamps for each value, and saves them to the local SQLite database.

(Note: If you are returning complex data arrays from custom logic, refer to the Custom Tool Buffer Support tutorial instead).