When you reset a Uno running the Optiboot loader, the bootloader first flashes pin 13 three times.
Top line (gray) is sent to the Arduino, middle line (orange) is sent from the Arduino.
While that is happening, the program avrdude running on your computer is sending a query to the device:
STK_GET_SYNC / CRC_EOP (0x30/0x20)
The Arduino doesn't notice the ...
The bootloader is a small program that is (almost) always on an Arduino. It manages uploading and starting the sketches you make, and blinks the pin 13 LED whenever the board resets.
To burn the bootloader:
Obtain an AVR ISP, USBtinyISP, ParallelProgrammer, or similar; or use another Arduino board. This will be your ISP.
Unless otherwise instructed, ...
The bootloader currently shipped on the official Arduino Nano boards and selected via the Arduino IDE's Tools > Processor > ATmega328P after choosing Tools > Board > Arduino Nano is the same version of optiboot used by the Arduino/Genuino Uno:
The answer needs to have multiple parts:
Yes, in principle you can create a bootloader for any microcontroller, which acts like the Arduino's.
Please be aware that there are different bootloaders, not just the common STK500 compatible one. Each of these bootloaders implements a certain protocol to transfer the binary code to the target system.
I successfully restored both boards using the reset button:
Power off the board (I disconnected the USB cable from computer)
Press and hold the reset button
Connect USB cable (keep holding the reset button)
Click "Upload Sketch"
Wait a second or two until Arduino software says "Uploading..." in the status bar
Release the reset button
Use these steps to ...
There are three things you can do:
Remove the bootloader entirely and program the board with a hardware programmer (USB-ASP, Another Arduino, etc).
Edit the bootloader source, recompile, and reinstall it to the board using a hardware programmer (as in option 1).
Just don't use pin 13 for the relay.
Of the three options the third one is by far the simplest.
What is a bootloader?
And what exactly is the bootloader?
The bootloader is a small piece of code residing in the "high" part of program memory. Normally it is not erased when you upload new sketches. Its purpose it to be activated immediately after a reset (the fuses are configured to commence code at the bootloader address rather than address 0x0000). ...
Optiboot is about the smallest bootloader available.
But, there is a much more powerful (with inbuilt console for hardware testing, RAM and Flash contents checking, etc) bootloader with a more developed and robust stk500v2 communications protocol between avrdude and the AVR bootloader.
I've used it on the ATmega2560 and on the ATmega1284p. It works for ...
Certain pins of the ESP8266 perform special functions at bootup. GPIO15, when HIGH, makes the ESP8266 boot from an SD card.
You can read more about the special functions of the pins here.
The solution? Don't use GPIO 0, 2 or 15 for things that can affect the boot sequence.
No, the ATmega's ISP does not operate over the UART pins but only the ISP pins.
To program it via a UART, you need to first load a bootloader, unless your chip was pre-programmed by the vendor, something some offer as a value-added service (or even as an essential stock item, with an Arduino type bootloader)
If flashing with AVR In System Programing (ISP) the bootloader is not needed. Only the flashing over Serial needs a bootloader.
The ISP erases the flash including the bootloader. To be able to use the serial flashing after ISP, the hex with_bootloader can be used.
I flash AVR over WiFi with esp8266's core AVRISP library and I use the hex with_bootloader ...
The Optiboot version 8 has a do_spm function which can be called from application. The Optiboot repository contains an example for the use of this function.
SPM is the AVR CPU instruction to write to flash memory. The Optiboot wraps this in a function. A pointer to this function is put in a 'vector table' at the beginning of the bootloader. The first pointer ...
The ICSP is used for 'bare metal' programming. This what you'd use if you wanted to replace or remove the bootloader, change the clock oscillator settings, or program the device as a bare 328.
The USB port is for communicating with a program running on the Arduino. When it's first booted, the bootloader program checks to see if there's any activity on the ...
In fact, you can, but you are unlikely to enjoy it as it will be fairly slow.
While this module is intended for serial communications - which the ATmega won't support until it has a bootloader on it - the chip around which it is built can also be operated in "bitbang" mode:
Step 1: Get yourself a programmer.
This can be anything from a USBasp to an Arduino programmed for ISP all the way to an AVR ONE!. Some can be used from the IDE, and some cannot.
Step 2: Set up the chip as expected from the entry in boards.txt and from the datasheet.
Add a crystal, decoupling caps, whatever. Don't connect power yet.
Step 3: Connect the ...
You have to keep some points in your mind:
(1) You have to ensure that pins must be not conflicting with each other. If you merge all sensor codes in one code then pins must be conflict. So you have to change pin number.
(2) If all sensors have separate working then make the function for all that sensors. It will very helpful for understanding and ...
It's enforcing this line from the arduino:avr boards.txt
To be clear, the board is assumed to have a bootloader, even if you're not using it to get the code onto the board, that is upload via programmer.
You could edit that and change some fuses yourself. But you could also probably just use MCUdude ...
Bootloader of the Mini and Uno are pretty much the same. (I can't find the source-code but the hex files are only slightly different).
The 2k is because they haven't updated mini328.upload.maximum_size in boards.txt. Probably because that would break the board for users that haven't updated the bootloader yet.
The 2560 is using a stk500v2 compatible boot ...
One of my projects does this too. I leave it connected to a USB port for power so it can control a room fan. Every 4 seconds it writes a line of data to the serial output. When I open a serial terminal on the computer, I immediately see a short stream of garbage, followed by the next, and all subsequent log outputs, properly displayed. It looks as if the ...
To preserve the bootloader, you should use the -D option in the ISP command line just as it was used in the bootloader upload command line. This will disable usage of full-chip erase.
I expect you would end up with something like
avrdude -c avrisp2 -p atmega328p -D -U flash:w:_build/image.hex
However, it is important to add something which I overlooked ...
In the Arduino IDE do this:
File > Preferences > Show verbose output during: > upload (check) > OK
Tools > Burn Bootloader
After it finishes examine the output in the black console window at the bottom of the Arduino IDE window. If you look carefully you'll see that the Arduino IDE actually runs two separate AVRDUDE commands when you Burn ...
First, the Arduino Uno has 32 KB of flash, but only 1 KB of RAM. So, to be able to store the new program in a string means your new program can only be, at most, 1kb.
Secondly, only the bootloader can write to flash. So you could write a new bootloader that downloads the new program (in parts) and writes it to the flash. You would however need quite a big ...
OK mystery solved!
I ended up getting Visual Micro Debugger plug-in for my Visual Studio 2013 since I am native .NET programmer. I could see that the code was indeed loaded onto the board and when I pressed the button it was indeed getting to the line of code for setting the digital LED to HIGH.
It was a very unfortunate case of trying different components ...
It is not possible to set the bootloader space to 0, but it is possible to unlock the bootloader space entirely by unprogramming the lock bits as well as to enable normal booting by unprogramming BOOTRST in the high fuse byte. Access to the entire chip will then be fully unrestricted.
The AVR pocket programmer should work fine. Sparkfun has a good guide for doing this.
Here's the pinout of the Atmega328:
You'll want to connect your programmer as follows (note, these are the pins for the bare Atmega328 chip only. The pin numbers on an Arduino board are different.):
Programmer Pin Atmega328 Pin
5V Vcc (7)
If you are using an LED to indicate that your sketch is running, then that may be the problem.
For example, if you have a fairly average red LED, it might have a forward voltage of 2.0v @ 20ma (refer to your spec sheet for your particular LED). Putting these values into the LED calculator, it would tell you that you need a 150 ohm resistor. You might have ...
It was a brownout fuse problem.
Changing boards.txt from:
solved it for me (*).
The chip and red LED now work at 3.01V (1xAA alkaline and 1xAA rechargeable) and 3.19V (2xAA alkaline).
(*) not sure why I had to invert the bits (0000 0010=0x02 versus 0000 0101=0x05)...