|
|
 CueCat meets Arduino
Soon after posting Arduino barcode scanner article I started receiving questions about CueCat. Many of these cat-shaped devices were distributed free of charge in the US at the end of the dot com craze and even though company which developed and distributed them went out of business long time ago, the USB CueCats are still available for very reasonable price. Declawed CueCat with USB interface can be purchased for as little as $13 total in the US and non-modified ones for even less; at the same time, typical no-name handheld barcode scanner goes for around $25 on eBay and will be shipped from China.
I tested “declawed” USB CueCat with my code – it initializes as HID boot keyboard and works very well. No modifications are needed to the sketch from the previous article – just plug in the device and start scanning. CueCat reads many different barcode systems, including UPC and ISBN. Since CueCat is in constant scanning mode (no button needs to be pressed to initiate a scan), it can be used for applications like automated inventory control or as a part of a motion feedback circuit in CNC/robotics project.
One last advantage of CueCat I’d like to point out is low power consumption. As can be seen on a title picture, an Arduino, USB Host Shield, CueCat and HD44780-compatible LCD display can be run from a small LiPo boosted to 5V by Mintyboost from Adafruit Industries with its output connected to Arduino USB port.
CueCat is compact and inexpensive barcode scanner still available for sale despite being discontinued many years ago. It is implemented as USB HID boot device and supported by USB Host library. If you were living in the US in 2000, chances are you already have one or even several of these cat-shaped devices laying around – try it with my code and let me know if you have any issues.
Oleg.
 Scanning barcodes using Arduino and USB Host Shield An addition of Human Input Device Class support to USB Host Shield library 2.0, announced several days ago allows using powerful and inexpensive input devices with USB interface in Arduino projects. Sample sketches demonstrating sending and receiving data to one of the most useful HID device types – boot keyboard/mouse, has been released along with the library. The beauty of boot protocol lies in the simplicity of device report – a data packet containing information about button presses and mouse movements. However, samples were designed to demonstrate all features of the class and because of that, they are somewhat heavy. In real-life applications, it is often not necessary to implement each and every virtual function – only what is needed. In today’s article I will show practical application of HID boot device building a simple gadget.
Originally, HID boot protocol was meant to be used with keyboards and mice. When USB became popular, other keyboard-emulating devices, such as barcode scanners and magnetic card readers have been migrated from PS/2 standard to USB while keeping their keyboard-emulating property. As a result, many modern “not-so-human” input devices behave exactly like a keyboard including boot protocol support. A gadget that I demonstrate today is portable autonomous barcode scanner built using Arduino board, USB Host shield, handheld USB barcode scanner and LCD display (see title picture). The operation is simple – when handheld scanner button is pressed, it scans the barcode and sends it to Arduino symbol by symbol. Arduino then outputs these symbols on LCD display. LCD is erased before outputting each new barcode by tracking time between arrival of two consecutive symbols. To keep the code simple, I intentionally did not implement any data processing, however, since Arduino sketch for the gadget compiles in just a little over 14K, there is plenty of memory space left for expansion.
Continue reading Connecting barcode scanner to Arduino using USB Host Shield
 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.
Continue reading Arduino-based controller for Canon EOS cameras
 HD44780 LCD display Introduction.
As time goes by, microcontrollers become more powerful, cheaper, and smaller. A typical micro of the past could have had 40 pins and no internal memory. On the contrary, modern J-series PICs are made with 96K program memory and 28 pins. We can drive a lot of peripherals with that amount of memory, however we are getting short on pins.
In this article I will show how to drive a parallel interface peripheral serially. A HD44780-compatible LCD module is good candidate – it is popular, inexpensive, and slow, so you won’t be losing any speed while converting parallel to serial. And you could even save some money using a micro with fewer pins.
Continue reading Interfacing LCD via SPI.
|
|
