[Limpkin] decided to give the whole embedded business card thing a try. Here is his finished project, a low-profile mass storage business card that doesn’t cost an arm and a leg. Sure, the $6 price tag could score him a hundred paper cards, but those don’t light up like this one does!
The main components on the card include an AVR microcontroller, a flash memory chip, and an ESD protection chip. The latter is to make sure a static shock on the USB connector doesn’t zap the MCU. Speaking of, he went with an AT90USB162 which runs from an external 8 Mhz oscillator. Sure, it’s not the fastest thing out there, but since there’s only 16 Mb of flash on this card we don’t think you’ll notice any data transfer delay. The processor is running the LUFA stack and has two flavors of firmware. One that enumerates as an HID keyboard to automatically use keyboard shortcuts to launch a browser and load up his website. The other implements a mass storage device.
If you don’t like the electronic route, you could always go with some laser cut metal. We’ve heard that [Kevin Mitnick's] business card has snap-out lock picking tools kind of like these.
Here’s an altered PCB that gives USB control to an Ikea Dioder. This is a $50 product that comes with four strips each containing nine RGB LEDs. The stock controller has a color selection wheel and a couple of buttons. [Rikard Lindström] wanted to use it to match ambient light to the colors of his computer monitor — yes, it’s another ambilight clone.
Since he already had a bunch of AT90USB162 chips on hand he chose that route. These chips have native USB support (he’s using the LUFA package which is a popular choice), but no on-board ADC. That means no need for the potentiometer from the original controller because there’s no easy way to read its value. Removing it made plenty of room for his add-on PCB. He also depopulated the PIC microcontroller that originally drove the unit, soldering to the empty pads in order to connect is own board. The finished product fits back in the original case, with the addition of a USB cable as the only visible alteration. Now he can dial in colors using a program he wrote.
In case you’re wondering, it looks like this is a newer version of control circuitry when compared to the original Dioder hack we covered.
Here’s a new option for building your own AVR programmer. It’s called the MkII Slim and the diminutive size makes it live up to its name. The design is rather spartan, using just three chips; a voltage regulator, a MAX3002 level converter, and an Atmel AT90USB162 as the main microcontroller. This chip has a built-in USB module, foregoing the need for a separate FTDI chip.
The firmware is built on the Lightweight USB Framework for AVRs (LUFA). This is a USB stack implementation originally called MyUSB that was developed by [Dean Camera]. Regular lurkers over at the AVRfreaks forums will recognize [Dean's] name, or his handle [abcminiuser] as a source for many of the high quality AVR tutorials found there. But we digress.
The programmer offers all the features you’d want in an In-System Programmer. It can easily be reflashed with future updates thanks to the bootloader running on the chip. There’s jumper-selectable power options, and it can program targets running at 3.3V or 5v. The full development package including code and artwork is available for download at the site linked above. For your convenience we’ve embedded the schematic after the break.
Continue reading “AVR programmer modelled after the MkII – uses LUFA”