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 Layout of USB Host Mini Detailed description of USB Host Mini has been added to USB Host Shield Hardware Manual. New information covers interface and power pins, pads and jumpers, as well as usage hints and possible board modifications. USB Host Mini is more difficult to use than its full size brother. I’m hoping that information posted will be useful for developers who incorporate my little board into their designs. If I missed something, please let me know. Oleg. Development of Arduino_Camera_Control library (which runs on top of USB_Host_Shield library written to support USB Host Shield ) continues at steady pace. Nikon point-and-shooters has been on a test bench for the last couple of weeks and they are already talking. Even more exiting is the fact that they are talking the language we already know – the plain old PIMA 15740-2000.  Arduino-controlled Nikon P100 It also looks like that PTP protocol implementation in all Nikons is very close to the standard with very few vendor extensions and it will be possible to use the same code base for both point-and-shoot cameras and DSLRs. In this article, I’m showing a lightweight implementation of Capture command for Nikon cameras. Unlike its’ sister sketches, The The following sketch does what other “…Capture” sketches do – it takes a shot once a second second in an endless loop. What makes it different is that it doesn’t use any vendor-specific code, compiles in ~9K and can be loaded into Atmega168-based boards leaving plenty of room for another functions.  USB Host Shield 2.0 pinout Today, I posted a static page containing USB Host Shield hardware manual. On this page, I give introduction to the shield hardware, explain board layout, connectors and jumpers. Finally, I show some useful modifications that can be made to the board to expand its capabilities. I decided to post it incomplete – at present, only 2.0 shields are covered. However, I’m not going to stop here – Mini will be described next followed by rev.1xx. Owners of rev.1xx may want to take a look at current page anyway since 2.0 and 1.xx are not that different. While writing this manual I tried to cover every detail. If you think that I missed something, please let me know! Enjoy,  USB Host 2.0 connected to Arduino Mega 2560 A major revision of USB Host Shield for Arduino has been released and is available in the store. The board’s improved layout makes this shield compatible with more Arduinos, makes it easier to use and opens new possibilities. The main differences from rev.1xx are outlined below:
 USB Host Shield 2.0 with AVR Dragon Besides “Mega-formfactor” compatibility, connecting to Arduino SPI signals on ICSP connector has several advantages. First of all, in this layout traces are much shorter and as a result, the shield works more reliably at higher SPI speeds and/or larger signal and power noise. Second, since the 2X3 connector, which comes bundled with the shield, is of ‘stackable’ variety, it is possible to connect AVR Dragon or other ICSP programmer to Arduino while USB Host Shield is mounted – picture on the left shows the arrangement. Finally, pins 11-13, occupied by SPI signals on “classic” Arduinos, are vacant on Megas and also uncommitted on the shield. Therefore, they can be used for other purposes without USB library code modifications. The shield comes in 2 configurations. One, called “Standard” is compatible with official full-size Arduino boards (Duemilanove, UNO, Mega, Mega 2560, and possibly others), as well as clones which supply both 3.3V and 5V to the shield. One example of such clone is BlackWidow; if you are aware about other compatible clones, please let me know. Another configuration, called “3.3V” is designed for battery-operated projects. It is compatible with Sparkfun’s Arduino Pro 3.3V board (I’m not aware of any other 3.3V-only full-size clones). It also supplies 3.3V to VBUS instead of spec’d 5V, therefore some bus-powered devices may function erratically (but not necessarily; I actually use bus-powered USB flash drive during final testing of production 3.3V shields). Self-powered devices, such as digital cameras, usually don’t care about VBUS voltage at all. Additionally, board layout makes it possible to mount external power supplies to generate 5V from 3.3V and vice versa, if necessary. The shield is compatible with current version of USB library. It is also very similar to rev.1.xx shield and information from previously posted articles is mostly valid for 2.0 board. Schematic and Eagle CAD files are also available for download. I am currently working on detailed description of the shield and hoping to get it ready in a week or two. Along with this shield I will continue producing rev.1.21 board – there are still “not-so-compatible” Arduino clones around. However, next major revision of USB library will not be compatible with rev.1xx shields; it will be possible to make it work after minor hardware/software modifications. As always, your questions and comments about the product are welcome and appreciated. Oleg. This is a quick post about another great project. Tomoyuki Tanaka AKA Tomo on this site, active in PS3 and Wiimote game controllers thread, AKA moyuchin on Youtube posted this little video of RC car controller made of Wiimote, Arduino Pro Mini and USB Host Shield Mini interfacing with Bluetooth dongle. Check out the video to see how speed, direction and steering controls have been implemented. Tomoyuki also made the code available on github. The code is based on Richard Ibbotson’s popular Wiimote Bluetooth code, as well as my MAX3421E and USB Host libraries. The code is well organized and even has a brief documentation in README file. Further development is on the way – Tomo is planning to add ultrasonic sensor support, so keep an eye on this repo. Good job, Tomoyuki and thank you very much for sharing your outstanding work! Oleg.  Canon A640 shooting Arduino board The Canon Powershot support for Arduino PTP Library has been released. The library code, as well as several examples, is posted to GitHub. The code allows remote controlling shooting parameters of certain Canon Powershot cameras ( see gphoto and Canon SDK pages for the list of cameras) via USB using Arduino board equipped with USB Host Shield. Every function of the camera available via buttons/menus can be initiated through PTP. This includes shutter button, shooting mode (Av, Tv, etc.), aperture and shutter speed values, zoom, focus, white balance, just to name a few. Code examples demonstrate control technique. In addition to examples, I added a static page with detailed description of Powershot library. Most PowerShot cameras have two modes of operation – ‘shooting’ and ‘PC connect’, selected by a switch on camera body. Typically, USB is deactivated in shooting mode and communication with camera is not possible; for remote shooting, camera has to be switched to PC connect mode. Newer PowerShots switch to PC connect mode automatically when USB connection is detected.  5V buck converter Today, I finished testing new lightweight boost converter. It is intended as a replacement for my ever-popular 3.3V to 5V converter. The new one is built around Texas Instruments’ TPS61240. It has slightly less output current (rated at 400ma) but is much simpler ( uses just 3 external components ), has several protections built-in, as well as undervoltage lockout (UVLO), which makes this power supply suitable for portable DIY devices. Take a look at the title picture as well as the datasheet. Here is why I like this controller. First, it has been designed for battery-operated applications – thanks to built-in 2.1V undervoltage lockout it is safe to run this converter from 3 NiMH cells or one LiPo; when battery voltage drops down to UVLO threshold, the converter automatically shuts down. Second, the working frequency of the converter is 3.5MHz, which means that small and inexpensive MLCC inductor can be used. The converter also works well with ceramic capacitors. The total part count is 4 including the IC, and all components are cheap. Lastly, over-temperature and over-voltage protections make this simple supply quite robust.  Arduino Camera Controller Today, I’m writing about two more pieces of digital camera control firmware that have being posted to PTP gihHub repository. Alex Gluschenko, the author of PTP library for Arduino, developed two sketches, one called EOSRemote and the other EOSCamController to demonstrate PTP library capabilities. The code allows requesting camera settings, such as shutter speed, aperture, ISO, etc., change them, as well as take shots. It supports Canon EOS cameras and was tested on EOS 400D, 450D, and 7D; other cameras with similar command set ( see my collection of PTP device info dumps ) may work as well. This is how the code works: when connection is established, camera sends back an initial packet with all its current settings along with a list of all possible values for each setting. Possible values depend on a camera model as well as lens that are mounted. For example, some cameras may have exposure compensation range from -2 to +2, others from -5 to +5; some lens have max.aperture 1.4, others – 3.5, an so on. The list of values received from the camera is placed in built-in EEPROM of Arduino microcontroller. After that, values are used in setting (called “property” in PTP lingo) change commands sent to the camera. When camera mode, such as Av, Tv, or lens is changed, camera sends initial packet again. The Arduino code tracks changes and updates the list stored in EEPROM. Hardware requirements for both controllers are pretty standard. The EOSRemote sketch uses Arduino serial port facility for I/O, and the only hardware necessary is Arduino Duemilanove, Uno, or compatible clone, as well as USB Host Shield. User interface is designed with simple terminal emulator program in mind. It can be used with a PC connected to Arduino directly or over some distance utilizing a pair of serial to RF converters, such as ever-popular Xbee. The following screenshot shows top-level menu with camera connected and recognized.  No SPI New version of USB Host library has been uploaded to gitHub. I managed to find a couple of bugs and solve some compatibility issues. The biggest change, however, has been made on the very lowest level of the library – SPI transfers between Arduino and MAX3421E registers. From the beginning, USB Host firmware relied on Arduino Playground SPI library. Starting from version 0018 of Arduino IDE, this library became part of the distro. Two versions after that, Arduino team decided to re-write SPI library, among other things changing function names. As a result, USB Host code became incompatible with “stock” SPI library. To remedy the situation, I incorporated SPI routines directly into MAX3421E support code. The new code is independent of Arduino SPI library and builds correctly on “old” (i.e. 0017) and “new” (0021) versions of Arduino IDE. In addition to that, new code accounts for SPI pinout difference between Arduino variants and works on both Atmega 328 and Atmega 1280/2560 based boards. ( Note: the current rev1.x USB Host Shield still needs to be modified to work with Megas ) The new library can be downloaded from USB Host Shield gitHub repository. If you are upgrading existing installation of the library, please make a backup copy before downoading! I checked it against all code examples and USB devices in my possession and everything works without a hitch. However, code written with tight timing may stop working because of speed difference since new SPI routines are slightly faster. As you can see in the title picture ( click on it to enlarge ), the line Oleg. Another popular USB peripheral code for USB Host Shield has been implemented! Collin Cunningham from Collin’s Lab @ MAKE found a neat way of interfacing USB MIDI devices with Arduino. The video above demonstrates using Akai LPK25 keyboard and USB video game guitar to play music on Arduino. Quoting Collin, his setup is “USB MIDI to old-school MIDI converter”. Make sure to check out Collin’s code – it’s one-piece sketch, short, clean and easy to understand. It is Richard Ibbotson’s PS3 code, re-purposed to parse MIDI data. While not a textbook implementation of USB MIDI, Collin’s code can be used to talk to MIDI keyboards, guitars, and consoles, to name a few. Good job, Collin! Oleg. |
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