Arduino Uno R3

The classic Arduino Uno with the ATmega328P. The most widely available Arduino board and a good starting point for learning CONDUYT. Limited memory means you'll want to keep module usage minimal.

Specs

PropertyValue
MCUATmega328P (AVR), 16 MHz
Flash32 KB (0.5 KB used by bootloader)
RAM2 KB SRAM
GPIO20 pins (14 digital + 6 analog)
ADC6 channels (10-bit), pins A0–A5
PWM6 channels (pins 3, 5, 6, 9, 10, 11)
I2C1 bus (SDA = A4, SCL = A5)
SPI1 bus (SS = 10, MOSI = 11, MISO = 12, SCK = 13)
UART1 port (TX = pin 1, RX = pin 0)
WiFiNo
BLENo
OTANo

Firmware setup

Arduino IDE

Select Arduino Uno from Tools → Board → Arduino AVR Boards. This board package comes pre-installed with the Arduino IDE - no extra setup needed.

PlatformIO

; platformio.ini
[env:uno]
platform = atmelavr
board = uno
framework = arduino
lib_deps = conduyt

pio run --target upload

Transport

Serial only (over USB). The Uno has no WiFi or BLE hardware.

#include <Conduyt.h>

ConduytSerial  transport(Serial, 115200);
ConduytDevice  device("MyDevice", "1.0.0", transport);

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

void loop() {
  device.poll();
}

Built-in LED

Pin 13. This is the standard Arduino LED pin used in all blink examples.

Memory constraints

With only 2 KB of RAM, the Uno is tight. Here's what costs memory:

FeatureRAM costGuideline
CONDUYT core~400 bytesAlways present
Each module~20–100 bytesStick to 1–2 modules
Each datastream~20 bytesKeep to 3–4 max
Receive buffer256 bytes (default)Can reduce to 128

To reduce the receive buffer:

// Add this BEFORE #include <Conduyt.h>
#define CONDUYT_MAX_PAYLOAD 128
#include <Conduyt.h>

Other tips:

  • Avoid Arduino String objects - they fragment the heap. Use char[] arrays instead.
  • Don't use Serial.print() for debug output while CONDUYT is running - it shares the same UART.
  • Compile with build_flags = -Os (PlatformIO default) for smallest binary size.

Common issues

  • "not in sync" during upload: Make sure the correct port is selected and all serial monitors are closed. Try: hold RESET, click Upload, release RESET when you see "Uploading..."
  • Erratic behavior after flashing: Usually an out-of-RAM condition. Reduce modules, datastreams, or payload buffer size.
  • Pins 0 and 1 don't work as GPIO: These are the hardware UART (Serial TX/RX). They can't be used for GPIO while serial transport is active.