In my zeal to keep my costs down on the Half-Byte Console project, I mistakenly ordered a bunch of ATMega328p controller chips without any bootloader. Oh well, I thought, they are easy to program. So, armed with Bing and the Goog, I set out find a simple, quick solution that would not require a tremendous amount of work. After all, I did order quite a few of them.
There are a lot of how-to’s out there, some of them really well done. But, they did require either things I do not have, like a breadboard (I know, I know!) or just took too long. Eventually, however, I stumbled across this post that pointed the way.
A sketch, called OptiLoader, is the key. Written by Bill Westfield, the loader can work with or without a computer. It requires two Arduino boards (I am using two UNO boards) with one UNO containing a programmed 328 with the OptiLoader sketch uploaded and a second, slave UNO with the unprogrammed (or programmed, if you want to change the bootloader) 328. You need to connect the two UNO’s like this:
Pin 10 on master UNO to RESET on the slave UNO
Pin 11 to Pin 11
Pin 12 to Pin 12
Pin 13 to Pin 13
Once the ‘master’ UNO has the sketch uploaded, and you have inserted the unprogrammed 328 into the slave, connect +5 and GND on the master to the slave to give it power (I am assuming the master already has power, if not, give it some.)
Once both are powered up, the master will check the slave to see what it is and then burn the correct bootloader. Once complete, the slave is shut down. Remove power and then remove the chip. At this point, you can program another by placing the new chip in the slave, apply power and then press reset on the master.
You can watch the progress on your computer if the master is connected. If it is, open a terminal window from the Arduino IDE, select 19200 for the baud rate and press reset on the master. The OpitLoader gives you all kinds of info and even tells you when it is ready to repeat the process.
OptiLoader is very well done and contains the images for the bootloaders.
This method takes less than a minute to do and works well.