My buttons are connected to pins 1, 4, and 7 on port D, so the implementation is straightforward. Note that this makes the pads narrower than the pins, so soldering will be harder. However, this requires the fuse to be un-programmed afterward. That was a lot of stuff, but if all goes well, we should have a limited functionality keyboard which is able to type three letters, and display the system lock key states! If you want to change the fuses, you will need to use an ISP or other programmer. Be sure to check out the dfu-programmer documentation before forging ahead with programming over USB. The project files are arranged as follows.

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One important note is that the entire chip has to be erased before you can run other commands on it. Success 0x bytes written into 0x bytes memory Success 0x bytes written into 0x bytes memory 2.

Second, it thickens up the contacts a bit so that they mate more tightly with the USB socket. The Eagle libraries also include supply parts which make it easier to create VCC and GND connections by dropping parts instead of naming nets.

This xplai that the microcontroller is able to talk to the computer and identify itself, and hopefully we are in a good position to program the board.

The following command does this and clears the lock bits in flash memory:. The rightmost button on the board connects PD7 and GNDso it can be pressed during reset to trigger this condition. This just temporarily enters the bootloader. Note that this makes the pads narrower than the pins, so soldering will be harder. Luckily, all AVR chips with hardware USB have fuses programmed by default to use the external crystal oscillator as a clock, which will work immediately as long as the crystal has a 8 MHz or 16 MHz frequency with correctly paired capacitors.


Finally, the two most interesting parts. Note that the schematic called for 22pF capacitors between the crystal terminals and ground, and 22 Ohm resistors on the zplain pins. Xplan Melenbrink suggested putting tape down over half of the chip to position it. Note that the compilation toolchain is basically the same, but the hex file is uploaded with dfu-programmer instead of avrdude.

Weeks AVR USB Devices and Programming

The final lines pull in the other LUFA libraries and tools, including the core drivers and microcontroller programming tools. The loop that follows just alternates between receiving data from the host and sending data back.

LEDs 1, 2, and 3 correspond to red, green, and blue respectively. You can find a useful albeit somewhat outdated guide for this here. ub

First up is to define masks in Keyboard. After the first program, the flash needs to be erased before being programmed again, so the erase-dfu target accomplishes that. After many hours of routing, I came up with this compact, symmetric design using the integrated USB connector.

We need some way to re-activate the bootloader to program the board. This serves two purposes.


The traces on this chip are much too small usbb solder individually. Although I used 6 offset paths instead of the normal 4, there are still copper traces around the edge of the board.

AVR Xplain

LUFA focuses on a modular approach to this software, and comprises the following parts at a high level:. This is the board, all laid out. The following command does this and clears the lock bits in flash memory: Adapting from the demo, the code for this is pretty straightforward: As a result, we have a nice way to program a board directly over USB, with no other xplaain required. A completely custom LUFA application would use the low-level modules to interact directly with hardware, and a custom driver on the host to communicate with the device.

Program the boot reset fuse, which always starts the board at the bootloader instead of the user code. Compared with the pins on the tiny44 and tiny45, they are much closer usv and smaller.

This Makefile uses the LUFA build system, which requires some variables to be set properly but otherwise handles both the building and uploading. Basically, this is a keyboard with just three keys.

This is where the USB hardware comes in.