The problem is that I don’t know if this scalable at all. UDR is the MMIO register I want to track, and if I run the compiled program under GDB with the following script: As a proof of concept I created this test program: x86 can signal if a memory location is accessed and it is used by debuggers to implement watchpoints (break on memory access). I have a few ideas on implementation, so my question is how feasible do you think they are, or is there any other way the achieve the same result? But the same concept (tracking memory access runtime) is used by memory debuggers with the help of instrumentation. Of course this cannot be done in C , the whole purpose of a native language is against this. If it would be possible to define a hook when a memory location is read or written, that would enable proper peripheral emulation and FW could be compiled mostly intact. In a desktop app this concept does not exist (unless you poke HW from userspace). MMIO access has side effects, different side effects for reading and writing. Unfortunately this method is intrusive (FW modification), and glue logic is highly dependent on the architecture of the FW (needs to be reinvented every time).įrom C/C point of view the most important difference between the FW and the code running on a proper OS is MMIO. Though the overall behavior is impacted by these changes, I found the end result very useful in many cases. If the FW is nicely layered then low level code can be substituted with glue functions without hacking too much. busy loop waiting on peripheral register change, or memory change by interrupt handlers), others end up as no op (writing into MMIO which on the real system trigger something), and fusing the FW's main loop with the GUI lib's main loop needs some creativity too. Some constructs in FW end up as infinite loops in the desktop version (eg. The first 3 steps is easy (and not much code for AVR's), the last one is tricky. Implement peripheral emulation code (lcd, eeprom)ĭo some GUI that reflects the original device's user interface (lcd, buttons) Provide HW related headers not existing on desktop (mostly MMIO register definitions -> global variables) I've done this before with AVR microcontrollers for a few projects and usually took the following steps: Running a FW as standard GUI application has lot of advantages like quick dev iterations, advanced debugging, automated testing, stress testing, etc. I don’t want to write a bytecode interpreter or binary translator I want to compile the original source. I want to compile and run microcontroller firmware (bare metal, no OS) on desktop linux. Instrumenting memory IO in C/C for hardware emulation Ok, some background on what and why? I may need to rework my code and adapt it to a direct avr-gcc / Atmel Studio compilation process. This is a rather simple way to workaround this problem, however it might not suit all cases. Using Timer2, I can still set an overflow AND an output compare interruptions on the same timer, as expected. If you want to define your own handler for this interrupt, you will need to build your project standalone, without using the Arduino library or tools. You're using the Arduino library, which already defines a handler for the TIMER0_OVF interrupt. This was tested with an Arduino Uno equivalent, Arduino IDE 1.8.5, text editor UltraEdit, and Windows 10. The same procedure may have to be applied to TIMER0_COMPA_vect as well (file Tone.cpp in the same folder). The interrupt handler is only disabled if preprocessor symbol _DISABLE_ARDUINO_TIMER0_INTERRUPT_HANDLER_ is defined. Note that for other Arduino projects it works exactly as before. #define _DISABLE_ARDUINO_TIMER0_INTERRUPT_HANDLER_ Then, in your source code put these two lines at the top of the file: On Windows this is done by right clicking on the text editor (a text editor that can handle the Unix end-of-line characters - Notepad can not really handle this) and selecting "Run as Adminstrator". Note that it may be necessary to have administrative privileges to make changes to wiring.c. Well, I wrote a small program, using timer0 (8 bits), and I need to trigger two interrupt service routines (ISRs):įor example, on Windows, file wiring.c may be located in folder C:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino. This project is also a pretext for me to learn how to have a better control upon my microcontroller. Then, I will use it to drive another microcontroller which handles the conversion from a raw signal (engine's commutator) to a clean output voltage, going through the RPM-counter's galvanometer. Atmel / Arduino: ISR(TIMER0_OVF_vect) won't compile (“first defined” in _vector_16) - c I'm currently working on a PWM modulator to "simulate" a car engine ignition commutation.
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