Electronic – arduino – “Faster” Arduino bootloader

arduinobootloader

The Arduino bootloader has a wait-time to facilitate "sketch" (code) uploading; this causes a delay of a couple of seconds before the start of the main code.

I would like to modify the bootloader file (specifically for the Arduino Mega) so as to reduce this time to less than 1000 milliseconds at most.

I am unsure how to get started on this — Could someone point me in the correct direction?

(Note: I am aware that I can instead directly upload only the hex file corresponding to my firmware, but in this case, I would like to maintain the bootloader.)

Best Answer

For an overview of the bootloader take a look at the Bootloader Development page.

The actual source code is available and can be browsed here. To modify the wait time (or the behaviour of the waiting) take a look at the ATmegaBOOT.c file.

In line 91 is MAX_ERROR_COUNT defined and used to determine when to start the actual application on your arduino. To decrease the waittime, I would start by setting MAX_ERROR_COUNT to a lower value.

After you posted your comment I had another look at the source code.

At line 433 the "forever loop" is startet and in line 436 the function getch() is called. In this function there is another loop, that checks for a received character. If no character is received within a given timespan the application code is getting called. The duration of the timespan is determined by MAX_TIME_COUNT.

So changing MAX_TIME_COUNT seems to be more suitable then changing MAX_ERROR_COUNT.

Related Solutions

Electronic – arduino – Upload to an Arduino from the command line

The arduino IDE resets the attached arduino before running avrdude. It does this by telling the FTDI device to pulse the DTR line which is attached to the arduino's reset pin. Pekkaa found the example perl code which does this and updated the thread on the Arduino forums.

For completeness here is the command they used to upload the .hex file:

perl -MDevice::SerialPort -e 'Device::SerialPort->new("/dev/ttyUSB0")->pulse_dtr_on(1000)'; \
./hardware/tools/avrdude -Chardware/tools/avrdude.conf -q -q -pm328p -cstk500v1 -P/dev/ttyUSB0 -b57600 -D -Uflash:w:/home/pekka/sketchbook/Blink2/applet/Blink2.hex;

There is also a python script for reseting arduinos which can be used in place of the perl one if you have trouble getting it to work on your system.

Electronic – arduino – Creating a sketch (.HEX) file from a .PDE file

When the Arduino IDE compiles your sketch it creates a .HEX file in a temp directory, which is then uses to upload to your board.

The .HEX file will have the same name as your sketch (without the .pde extension), followed by .cpp.hex

I just tried a build and the .HEX file was created in a directory called build2849146248544311107.tmp inside my Temp directory (C:\Users\USERNAME\AppData\Local\Temp\ on Windows 7). Presumably the numbers in the build2849146248544311107.tmp directory name will chanage.

Best Answer

Related Solutions

Electronic – arduino – Upload to an Arduino from the command line

Electronic – arduino – Creating a sketch (.HEX) file from a .PDE file

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