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This article will discuss how several hybrid architectures work with Internet connectivity.
Two basic sets of products can make use of Internet connectivity. One is the so-called "Internet appliance," which relieves consumers of the complexity of a PC. These devices include Web pads, e-mail and feature phones, Web-enabled cell phones, and PDAs and provide frequent user-friendly connectivity to the Internet. Another set of products includes most household and industrial appliances that need connectivity only occasionally. For these machines, network capability will bring about a quantum leap in their performance and available features.
For example, an appliance manufacturer could monitor a washer and dryer in a consumer's household by remotely running periodic diagnostic tests on the equipment. Problems could be instantly and remotely detected then addressed with a scheduled service call before significant degradation in the machine occurs, and even before the consumer is aware of any problem. The various food service appliances in a fast food chain's kitchens could be linked with a central, off-site computer that would provide capabilities such as automated cooking, monitor and control of cooking and refrigeration temperatures, inventory control and preventive diagnostics. The result would be improved consistency in food quality and efficient collection of data. In addition, the rollout of new menu items could be facilitated by the direct programming of appliances from the central computer, eliminating the threat of improper cooking by staff unacquainted with the new item.
Similar gains in efficiency and ease of use will apply to commercial laundries, HVAC equipment for home and industry, vending machines, fitness equipment, and an enormous range of industrial machines as well (see Figures 1 an 2).
[Figures 1 and 2. Variety of home and industry appliances]
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With increased demand for applications to provide real-time data processing and intensive calculations, traditional MCUs lack the ability or performance bandwidth to provide these optimized features (Figure 3). Many of these new application requirements are best dealt with by a digital signal processor, (DSP). DSPs, often identified as ultra-specialized microprocessors, are designed to perform a set of computationally intensive tasks efficiently and quickly.
[Figure 3. Comparison of MCU and DSP features for TeleDataCom and motor control applications]
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DSPs are optimized for the performance of mathematically intensive tasks such as filtering, compression, and other manipulations of data. Below are some application examples in key industrial and telecom markets that illustrate where a DSP is best utilized. n HVAC and compressors: Real time calculation for motors and dynamic model conversion for motor controls n Appliances: Real time calculations including voice/data communications and other (temperature, flow, time) controls for smart appliances n Stepper motors - multiple motion control coordination: each motion control has its own dynamic model conversion n Industrial control: Real time calculation for nonlinear control modeling (e.g., temperature, pressure, gas and fluid flows, electric voltage/current) n UPS: Real time calculation for detecting the main power failure and no-glitch switch to back-up power supply n Actuators - control drivers for valves: DSPs perform real time calculation to decide how to control the actuators that drive the valves n Voice enabled: Real time calculations including voice compression and decompression, along with Echo cancellation, voice recognition, and other supporting telephony overhead
To accommodate the special needs of Internet-connected appliances, new forms of electronic circuits must be designed that are optimized for an entirely new set of performance criteria. A key element in bringing network intelligence to appliances will be devices that can combine the capabilities of two common but distinct circuit types: DSPs and MCUs. The combination of DSP and MCU capability will bring about an era of appliances of all kinds, running at optimized performance levels, requiring minimal maintenance, and offering features previously unavailable.
To address applications requiring both control and intense math calculations, manufacturers have developed system solutions that combine the capabilities of DSPs and MCUs. The simplest and most common solution is having a separate MCU and DSP on the system. Such an investment, however, can be expensive, especially for lower-end applications requiring cost effective solutions. This configuration also takes up an inordinate amount of board space.
One evolved approach is the so-called dual core integrated circuit. In a dual core IC, the single chip contains the two separate cores, one for DSP functionality, and another for MCU functionality. The dual core solution provides limited relief for the system's operative space and provides the solution for the functional challenge. However, it does not solve the expensive investment of managing dual-core software developments and tools. Software designers or developers must expand their knowledge to two compilers (one for DSP and one for MCU) to adequately support the application development. As such, companies have to increase their resource investment and time-to-market penetration.
Since the early 1990s, Motorola recognized the need for a more comprehensive solution. The result was the development of the hybrid architecture (Figure 4), which contains both DSP and MCU functionality in a single architecture. With such architecture, investment in software and application development is more efficient, as designers use a single environment for their development efforts. The hybrid architecture also takes up less space, conserving additional valuable system space. This architecture provides an efficient approach to Internet type connectivity.
[Figure 4. Motorola 56800/E hybrid core example] Motorola's 56800/E hybrid architecture, the first commercially available DSP/MCU hybrid technology, was developed to solve similar problems in a host of applications, including automotive (for electronic power steering assistance, brake-by-wire, collision avoidance), telecommunications, IP phones, and appliances. All of these applications face similar needs for both MCU and DSP functionality and low price. Below (Figure 5) are some applications that are ideal for the Hybrid 56800/E core.
[Figure 5. 56800/E application examples] In developing the first hybrid core, Motorola engineers were forced to overcome significant challenges. To be an effective solution, the core had to offer significant savings in constructive space and power consumption, a difficult task when combining two sophisticated processor technologies in a single circuit. To avoid problems of added cost, space, power consumption, and complexity, Motorola's hybrid core was developed with a streamlined architecture combining the most critical functions of MCUs and DSPs at reduced cost - literally pennies per millions of instructions per second (MIPS). Some of the most critical functions are illustrated below (Figure 6).
[Figure 6. Motorola 56800E MCU functionalities] The processor requirements of Internet-connected appliances are relatively modest. The first generation 56800 hybrid core offered a 40 MIPS speed and up to 128 Kbytes of Flash and RAM memory, which are high in demand. Today's second-generation 56800E hybrid core offers speeds to 120 MIPS and up to 256 Kbytes of Flash and RAM memory with a migration path to 250 MIPS, more than enough for the bulk of current appliance needs.
A hybrid architecture like that developed by Motorola offers embedded systems designers a design methodology that allows use of familiar programming techniques, fast turnaround from spec to production, and a cost-effective solution for a wide range of tasks. The combined core offers the ease of programming of MCUs with the higher computational power afforded by DSPs.
Already, hybrid cores have been commercially applied to optimize motor control in appliances and other equipment. Electric motors, consuming 60 percent of all electrical power generated in the United States, can cut their power usage 30 to 50 percent by using hybrid DSP/MCU-based motor control strategies. For example, instead of cycling a refrigerator compressor ON, then OFF, which requires a high starting torque, a smaller compressor with a smaller motor run with hybrid core control could be used to operate continuously at low speed and adapt its torque to maintain the desired refrigeration temperature without constantly starting and stopping. For washing machines, it is estimated that efficient control can provide 50 percent savings in electricity and water. Similar benefits are realized in machine tools.
In addition to energy efficiency, another important requirement demanded by today's appliance customer is less noise. To provide quiet control for a three-phase motor, MCU capability is not enough, and the computational power of a DSP is necessary. Government regulations also require three-phase motors to receive high quality electrical power, an opportunity for power factor correction methodology, which also benefits from DSP use. In motor control, hybrid architecture offers low cost, high performance, low power consumption, and efficient programming code.
Internet connectivity for appliances presents a new set of challenges that hybrid cores are uniquely suited to address. With home networking, consumers will receive constant Internet access for their home environment. Typically, a high bandwidth "pipe" running one of a variety of protocols - wireless, analog, or broadband modem, etc., - connecting the household appliances will not only allow diagnostics run by the manufacturer, but will also allow users to control their own home appliances remotely. For example, users traveling or on vacation could, through their PC and the Internet, control and monitor household functions like thermostat settings and temperatures in the water heater and refrigerator; disable the surveillance system to permit a washer repair person to enter; and watch that person complete the repairs. However, for all these control issues, power consumption must be kept to a minimum. In the event of a power failure, battery backup must often function for as long as four hours for security systems, power meters, and other equipment. Power consumption by electronic control systems must be low enough so as not to fail during operation of battery backup systems.
A hybrid core solution is not appropriate for every appliance application. Some devices require a consistently high level of performance in terms of either DSP or MCU functionality. In such cases, a dual core chip is probably needed. For example, a 3G or Web-enabled cellular phone needs a dedicated MCU core to handle the control functions, the Web access, and the video streaming, etc. The question of whether an application's needs are adequately serviced by a hybrid core is largely a matter of needed horsepower.
For some appliances having technical demands that are not great enough to currently justify the expense of both DSP and MCU capability, the use of a hybrid core presents a roadmap. Incorporating the core today will allow for easy and inexpensive upgrading later, without the necessity of changing the software and allocating resources to a new and more expensive technology.
Hybrid architectures are not a universal solution, but for any control application that can benefit from Internet connectivity or from both MCU and DSP capability, hybrid cores generally offer a cost effective, low power, and high performance solution.
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