AVRSimV2 - a cross-platform simavr extension for back- and frontend emulation of peripherals

This project uses simavr.

Disclaimer

This simulator is only meant for quick and easy testing.
As it is only a simulator it might not always behave exactly like the real thing, especially when it comes to timings (see Known Issues).
Final checks should therefore only be made with a real board (e.g. PC-Pool).

Contributing

AVRSimV2 is not finished and has room for expansion. Feel free to open new issues.
If you want to contribute or have any ideas or suggestions you are welcome to contact me (information below).

Features

• Windows support!
• Easy to use API
• Extendable board architecture
• Auto layout system for GUI
• XML parser for custom boards/GUIs
• Emulation (+ GUI) of:
  • LCD
  • LEDs
  • External SRAM (SPI)
  • General memory visualization
• Emulation (currently no GUI) of:
  • Buttons
• Debugging support
• UART support (example)
• Everything else that simavr has

Also see usage for a more detailed explanation

Requirements

Besides standard libraries this project uses:

• simavr
• elf
• opengl
• GLEW
• glfw (v3)
• freetype (v6)
• xml2

For Windows all required libraries (or their ported versions) come packaged with this repository.

Installation

The most recent releases should be here or in the releases directory.
The installation depends on your environment. If you have trouble to setup AVRSimV2 feel free to contact me (see below).

Unix

Use CMake to compile or use the binaries directly. That's it...
Be aware that you might have to install some libraries first.

Windows

Use CMake to compile or use the executables directly.

Quick Start Guide for Windows

1. Unpack the latest avrsimv2-win-x.x.x.zip to a location of your choice.
2. Open a command line and make sure you can access the avrsimv2.exe from it (cd into the directory or append the location to your path).
3. Run avrsimv2.exe with the necessary arguments (see Usage and Examples (Windows)). Make sure that any relative filepath passed as an argument is accessible from your current directory.

Usage

avrsimv2 [OPTION]... firmware

Examples (Windows)

• avrsimv2 -m atmega644 -f 20000000 -b boards/psp_board.dll -x -g 1234 SPOS.elf
  This will simulate with a frequency of 20MHz and visualization the atmega644 on the board "boards/psp_board.dll" with GDB on port 1234 and load the firmware "SPOS.elf"
• avrsimv2 -m atmega644 -f 20000000 -b boards/board_xml.dll -a boards/psp_board.xml -x SPOS.elf
  This will simulate with a frequency of 20MHz and visualization the atmega644 on the board "boards/board_xml.dll", pass "boards/psp_board.xml" as an argument to the board and load the firmware "SPOS.elf"
• avrsimv2 -m atmega644 -f 20000000 --xml boards/psp_board.xml -x SPOS.elf
  This is the same as the previous command, but requires "boards/board_xml.dll" in the same directory as the executable.

Examples

• avrsimv2 -m atmega644 -f 20000000 -b boards/psp_board.so -x -g 1234 SPOS.elf
  This will simulate with a frequency of 20MHz and visualization the atmega644 on the board "boards/psp_board.so" with GDB on port 1234 and load the firmware "SPOS.elf"
• avrsimv2 -m atmega644 -f 20000000 -b boards/board_xml.so -a boards/psp_board.xml -x SPOS.elf
  This will simulate with a frequency of 20MHz and visualization the atmega644 on the board "boards/board_xml.so", pass "boards/psp_board.xml" as an argument to the board and load the firmware "SPOS.elf"
• avrsimv2 -m atmega644 -f 20000000 --xml boards/psp_board.xml -x SPOS.elf
  This is the same as the previous command, but requires "boards/board_xml.so" in the same directory as the executable.

Debugging

The -g port option starts a GDB Server on the specified port. One can either manually connect to it or use an IDE.
Most IDEs support GDB Server as a target or have a plug-in that has this ability. Atmel/Microchip Studio has (to my knowledge) neither.

Keep in mind that simulating while debugging can be much slower.

Screenshots

Tips and Tricks

UART

The Universal Asynchronous Receiver/Transmitter (UART) allows us to send or receive information on the microchip. To use stdout on your mcu for debugging you could do something like this:

#include "atmega644constants.h"
#define BAUD 9600UL               // used in <util/setbaud.h>
#include <util/setbaud.h>

static int uart_putchar(char c, FILE *ignored) {
    if (c == '\n') uart_putchar('\r');
    while (!(UCSR0A & (1 << UDRE0)));
    UDR0 = c;
    return 1;
}
static FILE _stdout = FDEV_SETUP_STREAM(&uart_putchar, NULL, _FDEV_SETUP_WRITE);
static void __attribute__((constructor)) uart_init(void) {
    UBRR0H = UBRRH_VALUE;
    UBRR0L = UBRRL_VALUE;

#if USE_2X
    UCSR0A |= (1 << U2X0);
#else
    UCSR0A &= ~(1 << U2X0);
#endif

    UCSR0B |= (1 << TXEN0);
    UCSR0C = (1 << UMSEL01) | (1 << UCSZ01) | (1 << UCSZ00);
    stdout = &_stdout;
}

Now you can use the printf-family and the simulator will print everything to console.

Known Issues

• Because simavr is not required to have precise cycle timings, delays and timing dependent constructs other than sleep_mode may not function as expected. AVRSimV2 tries to combat this by delaying simavr cycles accordingly. However, this solution is far from perfect, as it can only coarsely adjust the timings.
• Under some circumstances the LCD shows wrong characters. This might be related to some simulation math issues and should be caused by simavr.
• Some crashes on Windows might lead to the current CMD instance becoming unusable.
• Unconfirmed segmentation faults on Windows. Reason unknown
• ...

Further Questions

Please feel free to open new issues or contact me at any time:

• Email: jonas.broeckmann@rwth-aachen.de
• Telegram: RWTH Informatik PSP