Arduino Sketches. Langbridge James A.

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СКАЧАТЬ and power efficiency. These devices live up to their name “tiny”; the smallest tinyAVR is 1.5 mm by 1.4 mm. The word “tiny” is only a reference to their size. Their power is comparable to the larger AVRs; they have multiple I/O pins that can be easily configured and a Universal Serial Interface that can be configured as SPI, UART, or TWI. They can also be powered with as little as 0.7 V, making them highly energy-efficient. They can be used in single-chip solutions or in glue logic and distributed intelligence in larger systems.

      There are more than 30 ATtiny devices, and they come with between 0.5 k and 16 k of flash memory, and range from 6-pin packages to 32-pin packages. You can find more information on the ATtiny series on Atmel's website at: http://www.atmel.com/products/microcontrollers/avr/tinyavr.aspx.

      While the ATtiny series are powerful devices given their size, no Arduino uses this device as its microcontroller.

      Other Series

      Atmel also has different AVR series: The XMEGA series deliver real-time performance, with added encryption using AES and DES modules, and includes an interesting technology, the XMEGA Custom Logic, reducing the need for external electronics.

      Atmel also produces a 32-bit version of its AVR microcontroller: the UC3. Supporting fixed-point DSP, a DMA controller, Atmel's famous Peripheral Event System and advanced power management, the UC3 is a formidable microcontroller. You can find more information on Atmel's AVR website at: http://www.atmel.com/products/microcontrollers/avr/default.aspx.

      The Different Arduinos

      The original Arduino was designed for one specific task, and it fit that task perfectly. With the success of the original Arduino board, the company decided to create more designs, some of them for very specific tasks. Also, because the original Arduino design was open source, several companies and individuals have developed their own Arduino-compatible boards, or have followed in the open source tradition, and have proposed their modifications to Arduino. Arduino has begun a certification program to ensure compatibility with boards that use different processors, with the Intel Galileo being the first to receive such a certification. Anyone is free to make their own Arduino-based derivative, but the name and logo of Arduino are trademarked. As such, you'll find a number of boards with names ending in “uino”, implying compatibility.

      WARNING

      Beware of counterfeits! Some companies propose Arduino boards that are cheaper than the original Arduino series, but these boards tend to have less reliable hardware. Arduino boards are cheap but still use good quality electronic components, whereas counterfeit boards may well use components that will not last as long. Paying a few extra dollars for a board helps Arduino finance more research to create new Arduino boards and software, and ensures a better user experience. You can read more about how to spot counterfeit boards at: http://arduino.cc/en/Products/Counterfeit.

      Arduino made the board design open source, but it still produces its own boards. These boards are known as official boards. Other companies also make Arduino-compatible boards.

      Arduino Uno

The Arduino Uno is the “standard” Arduino board and the most readily available. It is powered by an Atmel ATmega328, with a total of 32 KB of flash memory, 2 KB of SRAM, and 1 KB of EEPROM memory. With a total of 14 digital I/O pins and 6 analog I/O pins, this is a very capable device, able to run most programs. An on-board ATmega16u2 chip manages serial communication. It is one of the least expensive boards and the most used. When starting a new project, if you do not know what Arduino to use, start with the Uno, as shown in Figure 1.3.

Figure 1.3 The Arduino Uno

      Arduino Leonardo

The Arduino Leonardo is slightly different to the Uno. Based on the ATmega32u4, this microcontroller has enhanced USB capabilities and therefore does not require a dedicated microchip for USB serial communication like the Uno. One advantage to this is cost; one less microchip means a cheaper solution. It also means that a developer can use the microcontroller as a native USB device, increasing flexibility in the communication with a computer. The Leonardo can effectively emulate a keyboard and mouse via USB HID, as shown in Figure 1.4.

Figure 1.4 The Arduino Leonardo

      Arduino Ethernet

      The Arduino Ethernet, based on the ATmega328 found in the Uno, can connect to an Ethernet network, a functionality needed in a number of projects. Physically, the Arduino Ethernet has the same 14-digital inputs/outputs as the Arduino Uno, with the exception that 4 are used to control the Ethernet module and on-board micro-SD card reader, limiting the amount of pins available.

      It is interesting to note that the Arduino Ethernet has an optional POE module, short for Power Over Ethernet. This option enables the Arduino Ethernet to be powered directly from an Ethernet connection, without the need for an external power source provided that there is a POE supply on the other end of the Ethernet cable. Without POE, the Arduino must be powered by an external source

Another difference from other Arduino boards is the lack of a USB connector. Because most of the space is taken up with an Ethernet connector, this device instead supports a 6-pin serial programming header and is compatible with numerous programming devices (including a device from Arduino, the USB-Serial adapter). The Arduino Ethernet is shown in Figure 1.5.

Figure 1.5 The Arduino Ethernet

      Arduino Mega 2560

      The Arduino Mega 2560 is only slightly larger than the Arduino Uno, but it has more input and output pins. It has a total of 54 digital I/O pins and 16 analog inputs. It also has a large amount of flash memory: 256 KB, capable of storing larger programs than the Uno. It also has generous SRAM and EEPROM: 8 KB and 4 KB, respectively. It also has 4 hardware UART ports, making it an ideal platform for communicating with multiple devices serially.

Arduino Mega boards are used when large amount of inputs and outputs are required. It is shown in Figure 1.6.

Figure 1.6 The Arduino Mega 2560

      Arduino Mini

The Arduino Mini is a tiny device, useful for applications where space is reduced to the absolute minimum (see Figure 1.7). It has 14 digital I/O pins and 4 analog input pins. (Four more are available but are not broken out.) The device has the strict minimum: it does not have a USB connector; it has no power regulator; and it has no headers. Programming is done via an external USB or RS232 to TTL serial adapter. It is shown in Figure 1.7.

Figure 1.7 The Arduino Mini

      Arduino Micro

      The СКАЧАТЬ