This is the status update on Arduino USB Host Mini development, announced 3 weeks ago. I received rev.0 PCBs last Saturday – BatchPCB is faster than ever! I made a test build (see title picture) and after fixing one major and several minor mistakes placed an order for what I’m hoping will be the final pre-production sample.
The prototype was built to sit on top of Arduino Pro Mini to make access to the parts easier during troubleshooting. On the final board USB connector is placed slightly further away from the pins; it will be possible to place Arduino on top of the shield so that the height of the “sandwich” will be less or equal to the height of USB connector.
In 2-3 weeks I’m hoping to finalize the design and start producing the USB Host Mini. Stay tuned!
Many people asked me to post a video showing an arm from inverse kinematics article in action. While making a video, I realized that shots of the arm following a pattern of computer-generated coordinates is going to be less than exciting and decided to add manual control. The video below shows the result. In addition to the video, a HID introductory page has been written describing HID communication basics as well as some simple Arduino code. Enjoy! ( Youtube link, where HD quality video can be selected ).
This post announces starting of development of new Arduino USB Host Shield variant. There are several projects in the works (thanks, guys for letting me know!), where standard size Arduino board is too big. Since electronics of USB Host Shield is pretty simple, it was decided to shrink the board as much as possible. Here is the first iteration.
The initial revision of USB Host Shield in Mini form factor is shown on title picture, It is intended to be used with Sparkfun’s 3.3V Arduino Pro Mini. Intended applications include digital camera control devices, robots, as well as any other projects where size and weight has to be minimized. The Gerbers was sent to BatchPCB; I’m expecting boards back in couple of weeks. The main goals of this first prototype are manufacturability check as well as checking claims made below.
The Mini Host is simplified version of full-sized shield; only USB and GPIO are available. By default, VBUS is routed to VCC, therefore only self-powered USB devices are expected to function (even though I have at least one USB flash drive which works fine powered from 3.3V VBUS). I also provided extra pads to simplify signal re-routing, however, since there was no place left for jumpers a trace has to be cut instead. The same has been arranged for VBUS – if 5V power is necessary, Arduino Pro Mini/Shield combination can be powered with 5V on RAW pin, the VCC trace cut off VBUS and RAW and VBUS connected.
As soon as first prototype is tested, I will post CAD files and also make boards available at BatchPCB. Stay tuned!
Blue Arduino USB Host Shield tied to telephoto lens mount
Developer Si Li shared his version of PTPDevinfo.pde, which fits into older Aduinos. Si wanted to get PTP device information from Canon EOS 500D, but he only has 16K Seeduino at hand. So he stripped devinfoparser off all unnecessary strings leaving only ones essential for parsing Canon EOS camera device info.
I’m starting new series of articles describing exciting field of digital camera control. In modern cameras, USB port can be used not only for transferring images to a PC, but also for sending control commands to the camera. It is often possible to send commands which “press” the shutter button, modify shutter and aperture values, some cameras are even capable of doing focus control. At the same time, new shooting techniques, such as HDR and stacked focus, require that a photographer makes several shots, slightly modifying one or several shooting parameters from shot to shot. Even age-old time lapse technique could use some automation. Since camera manufacturers are, as always slow to implement there cool features, Arduino comes to the rescue.
I am announcing new code developed for Arduino USB Host shield which implements digital camera control functions via PTP. Alex Glushchenko, a developer from my native Russia, recently joined camera control project and code shown here and in the future articles is mainly his. He did most of reverse engineering and code development and my contributions to this project were mainly code testing, camera borrowing, and blogging. Code is hosted on github separately from USB Host library. Be warned – this source is preliminary and will be changed many times before it becomes stable! It is also expected to grow quite a bit – different cameras use different commands and developing universal code supporting all manufacturers (or even every camera from one manufacturer) is not possible due to the modest resources of Arduino platform. Therefore, several libraries have been developed, each covering specific set of cameras. The cameras supporting functions of a certain library are listed in library’s header file. The list of cameras is currently quite small but I’m hoping to get more cameras supported in the future.
Digital camera as USB peripheral is much more complex and less standard than a keyboard. The complexity starts at the very first level – device configuration. Very often , several different configurations are supported on a device and the default configuration is not the one we need. Therefore, the first step would naturally be learning how to recognize configuration which supports camera control commands.
There are 3 specifications describing USB digital camera works. Still Image Device specifies USB requests, descriptors and endpoints. The protocol structure is described in Media Transfer Protocol (MTP), which is better known by its previous name, “Picture Transfer Protocol” (PTP). The most interesting document, which actually lists commands supported by camera class, is known as “PIMA 15740-2000″. It is available for a fee from I3A, however, second-hand pdf copy can be obtained for free after some googling. Camera manufacturers implement their own functions, expanding PIMA definitions. In addition to that, some older cameras use their proprietary protocols instead of PTP; support for such cameras will be added eventually.
USB isolation is good for you. Isolated DAC makes better sound, isolated oscilloscope produces cleaner trace, and making line voltage measurements with isolated instruments helps us live longer. However, USB isolation often comes with a cost of extra USB cable, which may become excessive if we take into account precious desk space taken by said cable, as well as time spent on finding and untangling it.
I made several attempts to build a short cable which would also be able to bear load of USB isolator. Finally, while searching for a source of PCB mounted USB male B-type connector, I found this little marvel on eBay.
There is not much to say about it. It is short rigid adapter with USB A-type connector on one end and B-type on the other. The following picture shows typical arrangement – USB isolator connected to my Bitscope with USB adapter holding isolator in the air.
Of course, this little adapter can be used for connecting many other devices. Another picture shows our beloved Arduino connected to a USB port of a laptop computer. Here the weak spot of the adapter is clearly seen – since A and B connectors are turned 180 degrees, connected device would be turned upside down. For isolator it doesn’t matter much; however, operating Arduino’s Reset button and connecting shields would be difficult.
Adapter is available from several sources on eBay. Prices vary from $0.90 to $2.00, often with free shipping. The search string is “USB 2.0 Male to Printer Scanner A-B Converter Adapter”. Enjoy!
Oleg.
USB Isolator connected to Bitscope using short cable
This is the third part of a series of articles written to describe development of interface between Arduino and popular game controllers using USB Host Shield. Previous parts:
Part 3. Develop the Bluetooth USB and HCI interface used in the support of the Wiimote and PS3 game controller, and also some utilities needed to analyse and configure these devices.
1. USB Interface
As before, we first look at the descriptors for the USB dongle using the USB_Desc sketch. The result is:
This is the second part of a series of articles written to describe development of interface between Arduino and popular game controllers using USB Host Shield. Previous parts:
Part 2: Develop the USB interface to the PS3 controller
1. USB Reduced Hosts
Full USB hosts such as Windows and Linux based computers can manage a large variety of different USB devices and load appropriate USB drivers for each device. There is an enumeration or discovery phase where the host gathers information on the attached USB device and uses this information for the driver selection and configuration. In small embedded applications this is not possible or required to support this variety, so the application usually only supports a few devices, often only one. This means the discovery process can be much reduced since the results are already known. This will reduce the memory required for the application by hard coding the device configuration into the application.
Though the configuration will be hard coded, we still need to initially gather the information from the device itself and other sources.
The existing device drivers mentioned above for Windows and Linux are important in our development process. The Windows drivers are usually complete, but not available in source form. Linux drivers are available in source form, though not always as complete. Device manufacturers are usually very reluctant to provide information required to build a driver or embedded application. So we rely on copying Linux code or “sniffing” Windows code to give us guidance.
1. Background
These articles describe how to interface PS3 and Wiimote game controllers directly onto the Arduino using the USB Host Shield. These controllers have not previously been directly connected to an Arduino due to the USB and Bluetooth interfaces and protocols used, and their relative complexity. The game controllers are a good match to the capabilities of the Arduino, and to the imagination of Arduino users, they have not only buttons and joysticks, but also motion sensing, and other goodies which deserve to be in the hands and ideas of Arduino users. Also I hope these articles provide some guidance for people to develop other USB host and Bluetooth applications for small embedded processors.
Arduino already comes in versions which have USB and Bluetooth interfaces, but these are not suitable for our chosen game controllers. When used in USB mode, the PS3 controller is a USB device and needs to talk to a USB host. The normal Arduino USB interface is also a device, so not compatible. When in Bluetooth mode, both of these game controllers use the Bluetooth HID protocol and this is not compatible with the commonly used Bluetooth modules which support only the RFCOMM Serial Port Protocol. Arduino users have successfully used a PC as an intermediary between the game controllers and the Arduino, so the PC is host to both devices.
These articles were written by Richard who is new to the Arduino, blogs, github, libraries, etc, so please give me any help and feedback on how I might improve or correct these articles and software.
PS3 controller connected to Arduino USB Host Shield
Another HID example has been added to Github repository of USB Host Shield for Arduino (which you can purchase in my store) . Richard Ibbotson sent me this nice piece of code along with some pictures. He also posted a short description of his sketch in comments section:
I wrote a sketch for the interface of the PS3 controller over USB. I have two controllers, one Sony and one Madcatz wireless with a USB dongle. Both of these work fine to the USB host shield. I only made one minor change to the library to increase the NAK count. The sketch tests all the function, buttons, joysticks, accelerometer/gyro, leds and rumble. This is not yet under bluetooth just USB. I can set the host bluetooth adddress on the controller though which is needed for bluetooth pairing.
Did not make much attempt to reduce code or data size, so only have about 4K of program space and 240 bytes of data space left, but sketch is pretty long. The actual PS3 part is very small and could be made to a small library.
Next is to move to the bluetooth part, from what I have found on the direct USB, I am pretty confident this will fit even on the 168.
PS3 controller support opens some very interesting possibilities. Not only can it be used as a normal “joystick plus buttons” type of control, but you can also utilize it’s accelerometer/gyro. With wireless variant of the controller all kinds of very powerful radio control are possible. Who is going to be the first to make a mechanical dog, which follows you around and brings back the controller when you throw it away?
If you want to try the sketch, make sure you have the latest library code as well – there are some small but important changes made recently in NAK handling.
MadCatz wireless controller to USB Host Shield
Wireless mini keyboard connected to USB Host Shield
