I'm working on a project that requires a number of arduno microcontrollers (11-12). The boards are very compact, all with SMD components, and there is no room to place the pins required to burn the bootloader in-circuit. Because I am using an SMD arduino (32 pin QFP), I have 3 options available:
1: Buy a whole lot of Arduino pro/nano boards and remove the chips from them. Not good at all, as it is vey costly and requires SMD desoldering which can be difficult and could result in some damaged chips
2: Make my own programming board, essentially and Arduino Pro board with a clamshell QFP socket. Its hard to find a clamshell socket in Australia, so if any of you could find where I could get one that would be great
3: Buy a chip with a pre-burned bootloader. This is the best option for me, if you know anyone who supplies the chips with preburned bootloaders i'd like to know as this would solve my problem
A bed of nails (e.g. with pogo pins like madworm says) would work.
I have also programmed one by etching a single board with only enough components to burn the bootloader and test. Instead of soldering, carefully hold the chip down on the pads by hand (by finger or thumb would be more accurate) and burn the bootloader.
thanks for the help, what i think ill do is use an aduino pro and desolder the MC on that, then i can hold the chip against the pads and burn the bootloader that way
I think you can use the FT232RL DTR option to program in the bootloader. I am planning to design a new mini board myself too. If this option does not work, let me know and maybe we can work together.
Instead of placing pins, do you have enough room to bring a trace out and put down a small pad? If there is enough room to squirrel that, you can then use the pogo-pin on a breadboard to program the bootloader in.
when the chip arrives, it's using the internal occilator and ready for low-speed ISP programming, which only really requires three pins to be brought out...