V-USB

28 Articles

USB On The ATtiny10

March 20, 2014 by 26 Comments

Atmel’s ATtiny10 is their smallest microcontroller in terms of physical size – it’s an SOT-23-6 package, or about the same size as surface mount transistors. The hardware inside this extremely bare-bones; three I/O lines, 1kB of Flash, 32 bytes of RAM, and a reduced AVR core with 16 registers instead of 32. With such a minimal feature set, you would think the only thing this micro would be good for is blinking a LED. You’d be right, but [cpldcpu] can blink a LED with the ‘tiny10 over USB.

The V-USB interface usually requires about 1.5kB of Flash in its most minimal implementation, and uses 50 bytes of RAM. This just wouldn’t do for the ‘tiny10, and although [cpldcpu] is working on a smaller, interrupt-free V-USB, there were still some hurdles to overcome.

The biggest issue with putting code on the ‘tiny10 is its reduced AVR core – on the ‘big’ 32-register core, direct memory access is two words. On the ’10, it’s only one word. AVR-GCC doesn’t know this, and no one at Atmel seems to care. [cpldcpu] worked around this problem using defines, and further reduced the code size by completely gutting V-USB and putting it in the main loop.

It’s not much, but now [cpldcpu] can blink an LED with a ‘tiny10 over USB. If you’re wondering, 96.4% of the Flash and 93.8% of the SRAM was used for this project.

Interrupt Free V-USB

March 4, 2014 by 24 Comments

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[Tim’s] new version of Micronucleus, Micronucleus 2.0, improves upon V-USB by removing the need for interrupts. The original Micronucleus was a very small implementation of V-USB that took up only 2KB. Removing the need for interrupts is a big leap forward for V-USB.

For those of you that do not know, “V-USB is a software-only implementation of a low-speed USB device for Atmel’s AVR® microcontrollers, making it possible to build USB hardware with almost any AVR® microcontroller, not requiring any additional chip.” One tricky aspect of using V-USB is that the bootloader requires interrupts, which can lead to messy problems within the user program. By removing the need for interrupts, Micronucleus 2.0 reduces the complexity of the bootloader by removing the need to patch the interrupt vector for the user program.

With the added benefit of  speeding up the V-USB data transmission, Micronucleus 2.0 is very exciting for those minimal embedded platforms based on V-USB. Go ahead and try out Micronucleus 2.0! Leave a comment and let us know what you think.

Software USB On The STM8

March 2, 2014 by 13 Comments

STM8

Thanks to V-USB, software-based USB is all the rage now, with a lot of uses for very small and low power microcontrollers.[ZiB] wondered if it would be possible to implement a USB controller on the STM8 microcontroller (Google translation) in software and succeeded.

The STM8 is a bit of a change from the usual 8-bit micros we see like AVRs and PICs. [ZiB] chose the STM8S103F3, although any chip in the STM8 family will work with this project when a 12MHz crystal is attached.

The build began by generating USB signals with the help of a whole lot of NOPs. This code doesn’t take up much space – only 300 bytes, and the receiving code (Google translation) is similarly sized.

The code isn’t quite there yet, but [ZiB] has proven a software-based USB implementation on the STM8 is possible. All the code is available for download (comments in Russian) and a video demoing the project available below. If anyone cares to translate this project to English, we’ll post a link to your work here.

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Introducing The SquareWear Mini, With Its Chainable Color LED Matrix

February 10, 2014 by 8 Comments

[Ray] just tipped us about his latest project: the SquareWear Mini, which basically is an improved version of the SquareWear 2.0 that we featured a month ago. For our readers that may have missed it, the SquareWear is essentially a wearable Arduino platform running at 3.3V and 12MHz. Both versions are based on an ATMega328 microcontroller running the V-USB library to provide USB connectivity, put together with diverse onboard peripherals.

As you can see in the picture above, the Mini includes 2 N-MOSFETs, one temperature sensor, one light sensor, a 16KB EEPROM memory, one buzzer, a one cell LiPo battery connector together with one charging controller, and finally a power switch (USB/battery). It is supposed to be 25% smaller than the SquareWear 2.0 and is optimized to work with a WS2812B-based 5×7 RGB LED matrix that [Ray] also designed. The latter can easily be cascaded in X/Y directions with other LED matrices in order to expand the overall display.

At last, [Ray] created a software to design animations and upload them to the SquareWear . A presentation video of the complete system is embedded after the break and you can download all the design files on GitHub.

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Chachka: A Trinket Clone

January 20, 2014 by 21 Comments

Why would you clone something as cheap as the adafruit Trinket? Well, because you can, of course. And that’s exactly why [Ray] started to build a clone two days after his Trinket came in the mail. He encourages you to support adafruit by buying at least one Trinket before attempting a clone, and we agree. Besides, you’ll be able to use the support forum with a clear conscience.

[Ray]’s design uses an 1800Ω pull-up resistor rather than the 1500Ω in the Trinket. He made this change based on his experience with V-USB and the ATtiny85. He has a lot more information on his build on the Arduino forum. Check out a short video of Chachka responding to a Sony-esque remote control after the break.

Need an application for your Trinket clone? Check out this incredibly well-built USB volume knob.

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USB Datalogging With Arduino Using V-USB

January 18, 2014 by 18 Comments

Adding USB functionality to your Arduino projects used to be a pain, but thankfully, the V-USB project came along and gave your ATMEGA328 the ability to control the USB lines directly and mimic simple (low-speed) USB peripherals. [Ray] shows an implementation of the V-USB project by logging the status of the Arduino’s I/O pins to an open Excel spreadsheet

V-USB (Virtual USB) is especially useful for those of us who build standalone Arduino projects with the ATMEGA328. Unlike the Arduino Leonardo and its ATMEGA32U4, the ATMEGA328 does not have a built-in USB controller. The circuit required to tie into the USB lines is made up of just a few basic components, and [Ray] provides a reference schematic and BOM to get you started. The Arduino is programmed to mimic a keyboard, so the datalogging is achieved by allowing the Arduino to ‘type’ the data into an open Excel spreadsheet. In this example, the status of 8 digital pins and all 6 Analog Input pins are logged.

For those of you who prefer the PIC microcontroller and are in a similar position of not having a built-in USB controller, there is the 16FUSB project to help you out.

SquareWear 2.0 A Wearable Opensource Arduino

January 12, 2014 by 37 Comments

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Are you guys tired of redesigned Arduinos yet? Usually we are, but [Ray] just released the SquareWear 2.0, and we have to admit, it’s a pretty slick design.

It’s an update to SquareWear 1.1 which we covered a year ago. That version made use of a 18F14K50 microcontroller, measured a tiny 1.6″ x 1.6″ and could easily be sewn into wearable circuits. But after receiving lots of requests to design a new Arduino based board, [Ray] obliged and made v2.0.

The new SquareWear is slightly bigger, measuring in at 1.7″ x 1.7″, but it packs a much bigger and more functional punch — just check out the image schematic above! The only catch is it doesn’t actually have a USB-to-serial chip on-board, which is why [Ray] was able to get the board so small and inexpensive. Instead it simulates USB in the software using the V-USB library. That method is much slower but still functional. To perform serial communication through the USB port it uses the onboard USBasp bootloader.

The board also features large through-holes to accommodate sew-able pin pads, making it super easy to integrate this into fabric!

For a complete explanation of the SquareWear 2.0, check out the video after the break.

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