Microcontroller Solutions TechZone Magazine, April 2011 - Digikey

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In all of the aforementioned deeply embedded devices, latency is not critical. Other applications where latency is not critical include security or environmental sensors, data-upload services for medical monitoring, and consumer news devices, as well as information servers. Deeply embedded devices don’t need 300 Mbps, 54 Mbps or often even 11 Mbps of throughput. A majority of deeply embedded devices use a low amount of bandwidth. They have data for transmission a few times a day, or expect to receive data possibly once a day. The amount of data they deal with is on the order of 100 bytes. By keeping external memory minimized or not using it at all, the overall system cost and power consumption remain low. A normal infrastructure connection provides about a 5-10 second reconnect period from the hibernation stage. The connect processing between the Wi-Fi radio and an access point takes about 176 ms. Connecting takes longer than this, so the majority of the time is spent in the delays associated with the access point dealing with the connection. This can be easily seen by virtue of the time it takes a standard laptop (a high-end open system) to connect to a network. This time can be reduced by using the static addressing feature of the Microchip TCP/IP stack. With such an operation, the connect time with security can be reduced to less than a second. Ad hoc connection from a power up can take less than 200 ms. For point-to-point-only remote-control devices, ad hoc operation is suitable because the achievable connection times are short. This method of operation is not often used for remotes because while it does resolve the connection-time problem, the limited use of the wireless technology for simple point–to-point only communications without LAN or internet connectivity can be better served by other wireless technologies, such as basic RF transceivers or the IEEE 802.15.4 protocol. A very good application of the ad hoc mode of operation is as a default mechanism to enable easy confi guration of the device onto the network of interest. Deeply embedded products that do not have a screen/keyboard to enter data need a method for the end user to confi gure the network, as well as the security parameters of their network. In this case, the codes can be entered using a temporary network. To use a temporary network, the product must be preconfi gured to start either searching for a pre-determined infrastructure network, or by creating a pre-determined ad hoc network. In either case, another computer or Wi-Fi-enabled device (e.g. iPhone, Smartphone, etc.) connects to the product using the pre-determined network, and then confi gures the product to the fi nal desired network. Once the appropriate network information is entered, a command can be sent to the product to restart in the desired network. One advantage of 802.11 for deeply embedded devices is the ability to use pre-existing networks and the Internet. There is some concern regarding the impact to performance for other computers that use the network, when a low-bandwidth, deeply embedded device is also attached to that network. Wireless communication is a shared-bandwidth, media-access mechanism. There is a fi nite amount of bandwidth available for all to use before the airwaves get saturated with signals. The biggest impact is from clients utilizing the available bandwidth. Thus, adding a second 802.11g laptop to a network that already has an 802.11g-connected laptop on it will reduce the available bandwidth by 50 percent. The hibernate mode described earlier for power savings also serves, in this case, to minimize the effect on the network of embedded devices. Embedded devices should be confi gured to buffer their information and burst as required. Such usage will allow the devices to get on the network, transfer their data, and then get off the network. The effect of this will be maximum power savings and minimal impact on network-bandwidth capabilities. Figure 4: Example of mixed devices in a network. A critical need of deeply embedded systems is to keep the communication system easy to implement and use. While the 802.11 protocol makes an ideal candidate for communication for these devices, many manufacturers are specialized in the art of their own product, and not in wireless IP communications. There is often no room in a critically costed product for more memory to run an operating system, in order to use an off-the-shelf driver that traditional 802.11 solutions offer. These drivers are created for complex operating systems, such as Windows, Windows Embedded CE, or Linux. A signifi cant benefi t of a solution like the Microchip 802.11 one is the ease of implementation to the developer. Along with the basic networking features of security, infrastructure, and ad hoc; the stack supports various services that a deeply embedded product developer would require. Some of the services supported are ICMP, HTTP, SSL, DHCP, FTP, SMTP, SNMP, TFTP, DNS, and Telnet. These are suffi cient for serving Web pages, sending and receiving data fi les, and handling e-mail services. The value to the customer is the ability to minimize code-space requirements by selecting only the services they require, accelerated time-to-market, and allowing concentration on device application and user interface, rather than on the underlying communications protocol. The “Internet of Things” is about connecting a diverse set of simple, deeply embedded devices to the tools we already use. It allows servers and other instruments that can work in the background to provide a clearer understanding of what is happening—whether the interest is in energy conservation, product maintenance, health and safety, or just information retrieval. The Microchip 802.11 solution has been designed with the mindset for deeply embedded devices. This solution takes into consideration the speed, bandwidth, and latency needs of embedded devices—these being much 42
less than what most people demand for their day-to-day Internet connectivity experience. This makes the solution much lower in power and easier to use than standard IP-connection alternatives. The solution is also compatible with the cost constraints of deeply embedded devices. These characteristics allow the system developer to concentrate on application development rather than on networking knowledge. While it is said that the “Internet of Things” will progress to a billion new connected things by <strong>2011</strong>, the majority of these will be in embedded and deeply embedded devices. The unique characteristic of IP connectivity is that having devices connected and providing improved effi ciency is not the only benefi t. The real return is the progression of benefi ts that will result from the interconnecting of devices to a wider and automated information database. This can include better performance through longer operation within optimal ranges, new revenue streams that will give users simplicity in dealing with things that otherwise go into disrepair, and also increased sales pull-through via product and information co-marketing. Intro to PIC24FJDA Family Microchip Technology The PIC24FJDA family from Microchip features graphic acceleration and direct interface to STN, TFT, and OLED displays. The series comes with 64-pin QFN, TQFN, and for the fi rst time BGA packages. The product training module for this series provides in-depth lists of the products’ many features, explains the properties of Power Consumption, and a cost comparison chart for budget planning. This module can be experienced with or without audio in approximately 15 minutes and is 24 pages in length. www.digikey.ca/ptm PIC24F04KA201 Family As more electronic applications require low power or battery power, energy conservation becomes paramount. Products with Microchip’s nanoWatt XLP Technology offer the industry’s lowest currents for Run and Sleep modes. The PIC24F04KA201 family is ideal for low cost, low pin-count applications (14-20 pins) which require up to 4 KB Flash that also need 16-bit performance (16 MIPS). This family includes a range of peripherals including timers, UART, SPI, I 2 C, ADC, comparators and CTMU for precise time measurement or touch sensing. With full analog and self write capability down to 1.8 V, the PIC24 “KA” family will extend the battery life in your next design. Use the free Microchip XLP Battery Life Estimator to select the target MCU, battery type, and energy profi le to get an estimate of battery life for your application. It’s easy to get started with the XLP MCUs, using the XLP 16-bit Development Board (DM240311), which includes current measurement terminals and fl exible power sources (AAA, coin cells or energy harvesting modules). Example applications for the new PIC24F04KA microcontrollers include: • Medical (portable and home medical devices, oxygen fl ow meters, lifestyle/fi tness monitors) • Industrial (energy harvesting/scavenging, water/gas/heat meters, portable gas sensors, remote sensor networks, asset tracking, sealed/harsh environment sensors) • Consumer (security-system dongles, sealed disposable electronics, portable electronics, smart cards) www.digikey.ca/microchip-mcu www.digikey.ca/microcontroller 43
Page 1 and 2: MICROCONTROLLER LIGHTING SOLUTIONS
Page 3 and 4: MICROCONTROLLER SOLUTIONS TZ M 112.
Page 5 and 6: Editorial Comment The Energy Manage
Page 7 and 8: The Ultra-Low-Power USB Revolution
Page 9 and 10: Figure 2: MSP430 USB microcontrolle
Page 11 and 12: MSP430x5xx Overivew Texas Instrumen
Page 13 and 14: The thermistor used in the circuit
Page 15 and 16: Introducing a Second MCU to Embedde
Page 17 and 18: Introduce complexity in stages: Do
Page 19 and 20: Eliminating the Parallel/Serial Tra
Page 21 and 22: Physical interface Figure 3 shows t
Page 23 and 24: Configure the IP address of the rou
Page 25 and 26: Usage considerations with uIP TCP/I
Page 27 and 28: The transport layer adds the most c
Page 29 and 30: DHCP client The Dynamic Host Config
Page 31 and 32: Voice synthesizer The RC Systems V-
Page 33 and 34: Drawback of XML documents The probl
Page 35 and 36: XML Streams For XML streams, the EM
Page 37 and 38: Computer connectivity The tremendou
Page 39 and 40: Are you a Microcontroller Solution
Page 41: Examples of deeply embedded, Intern
Page 45 and 46: Table 1: Reflex producers. Module R
Page 47 and 48: The function PRS_ScanChannel(TIMER_
Page 49 and 50: Figure 2: Schematic diagram from th
Page 51 and 52: 6. If not, it attempts to retransmi
Page 53 and 54: • How fast do I have to read the
Page 55 and 56: 1) Can.h The CAN structure CAN_Msg:
Page 57 and 58: Two IRQ events are shown. Note an I
Page 59 and 60: Figure 3: Timeline window. Another
Page 61 and 62: The Heartbeat Behind Portable Medic
Page 63 and 64: While MCU suppliers continue to inn
Page 65 and 66: USB 3.0 is clearly overkill for HID
Page 67 and 68: Digi-Key, at your service. Programm

Microcontroller Solutions TechZone Magazine, April 2011 - Digikey

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