debugSerial Library for AVR

A lightweight, transmit-only UART debugging library designed for the ATmega328PB microcontroller using UART1. It supports printing strings, integers, and floating-point numbers. This library is intended for bare-metal development in Microchip Studio and is compatible with AVR-GCC.

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Features

• Buffered UART1 transmission using a ring buffer (size: 100 bytes).
• Functions: debugPrint, debugPrintln, debugPrintInt, debugPrintIntln, debugPrintFloat, debugPrintFloatln.
• Configurable baud rate.
• Transmit-only: Does not support receiving data.
• Designed for ATmega328PB (which has two UARTs: UART0 and UART1).
• Adaptable for ATmega328P (which has only UART0) by modifying register names.

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How UART Transmission Works

The library uses the ATmega328PB’s UART1 module to transmit data serially. UART (Universal Asynchronous Receiver/Transmitter) sends data as a series of bits over a single wire (TX pin, PD3 on ATmega328PB). The library:

• Configures UART1 with a specified baud rate, 8-bit data, no parity, and 1 stop bit.
• Uses a ring buffer to store outgoing data, allowing non-blocking writes.
• Employs interrupts (USART1_UDRE_vect) to transmit data when the UART data register (UDR1) is empty.
• Does not support receiving data, as it only enables the transmitter (TXEN1).

Connect the TX pin to a serial-to-USB adapter or similar device to view output in a serial monitor (e.g., PuTTY, Tera Term or Microchip Studio’s Data Visualizer).

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Installation in Microchip Studio

Step 1: Download the Library

Clone this repository or download the ZIP from GitHub Releases.

Step 2: Add Library to Project

1. Create a new project in Microchip Studio:
   File > New > Project > GCC C Executable Project.
2. Select your microcontroller (e.g., ATmega328PB).
3. Copy the src folder (containing debugSerial.h and debugSerial.cpp) to your project directory.
4. In Solution Explorer, right-click the project > Add > Existing Item.
5. Select debugSerial.h and debugSerial.cpp from the src folder.

Step 3: Define F_CPU

The library requires F_CPU to match your microcontroller’s clock frequency (e.g., 8000000UL for 8 MHz or 16000000UL for 16 MHz) for accurate baud rate calculations.

Option 1 (Recommended): Define in project settings

• Go to Project > Properties > Toolchain > AVR/GNU C Compiler > Symbols.
• Add a symbol: F_CPU=16000000UL (or F_CPU=8000000UL).

Option 2: Define in your source file

#define F_CPU 16000000UL
#include "debugSerial.h"

Step 4: Use the Library

• Include the library: #include "debugSerial.h"
• Initialize UART1 with debugSerialBegin(9600)
• Use print functions (e.g., debugPrintln("Hello")).
• See the examples/debugExample/main.c for a sample program.

Adapting for ATmega328P

The ATmega328PB has two UARTs (UART0 and UART1), but the ATmega328P has only one (UART0). To use this library with ATmega328P:

1. Open debugSerial.cpp
2. Replace the following UART1 registers with UART0 equivalents:
   • UBRR1H → UBRR0H
   • UBRR1L → UBRR0L
   • UCSR1A → UCSR0A
   • UCSR1B → UCSR0B
   • UCSR1C → UCSR0C
   • UDR1 → UDR0
   • USART1_UDRE_vect → USART_UDRE_vect
3. Update the TX pin to PD1 (UART0 TX on ATmega328P).
4. Recompile and upload.

Limitations

• Transmit-Only: The library does not support receiving data.
• UART1-Specific: Designed for ATmega328PB’s UART1. Modification required for other UARTs or microcontrollers.