Microcontroller Solutions TechZone Magazine, April 2011 - Digikey

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ARM7 Core MicroConverter Applications and Tools Analog Devices, Inc. Analog Devices’ ARM7 series integrates high-precision analog with an ARM7TDMI core. The small size and integration of these devices makes them particularly useful in a wide range of applications. Experiencing the product training module regarding the ARM7 series will provide insight into the industrial and medical applications of which the device is often utilized, along with example MicroConverter reference design examples for the benefi t of any purchaser. USB-Based Emulator (ADZS-USB-ICE-ND) Analog Devices’ cost-effective Universal Serial Bus (USB)- based emulator provides an easy, portable, non-intrusive, target-based debugging solution for Analog Devices JTAG processors and DSPs. This powerful USB-based emulator performs a wide range of emulation functions, including single-step and full speed execution with pre-defi ned breakpoints, and viewing and/or altering of register and memory contents. With the ability to automatically detect and support multiple I/O voltages, the USB emulator enables users to communicate with all of the Analog Devices JTAG processors and DSPs using a full speed USB 1.1 on the host PC. Applications and data can easily and rapidly be tested and transferred between the emulators and the separately available VisualDSP++ development and debugging environment (sold separately). www.digikey.ca/ptm www.devtoolsxpress.com ADuC7122: Precision Analog <strong>Microcontroller</strong>, 12-Bit Analog I/O, ARM7TDMI MCU The ADuC7122 is a fully integrated, 1 MSPS, 12-bit data acquisition system, incorporating high performance multichannel ADCs, 12 voltage output DACs, 16-bit/32-bit MCUs, and Flash/EE memory on a single chip. The ADC consists of up to 13 inputs. Four of these inputs can be confi gured as differential pairs with a Programmable Gain Amplifi er on their front end providing a gain between 1 and 5. The ADC can operate in single-ended or differential input modes. The ADC input voltage is 0 V to VREF. A low drift band gap reference, temperature sensor, and supply voltage monitor complete the ADC peripheral set. • 13 external channel, 12-bit, 1 MSPS ADC • 11 general-purpose inputs • 0 V to VREF analog input range • 12 × 12-bit voltage output DACs • ARM7TDMI core, 16-bit/32- bit RISC architecture • JTAG port supports code download and debug • 41.78 MHz PLL with programmable divider • 126 kB Flash/EE memory, 8 kB SRAM • UART, 2 × I 2 C ® and SPI serial I/O • Wake-up and watchdog timers (WDT) • Specifi ed for 3 V operation • Active mode: 11 mA at 5 MHz, 40 mA at 41.78 MHz Analog Devices and Digi-Key present New Product Express – a fast, easy way to get ADI’s newest products. These products are in full production, having passed ADI’s quality and reliability testing, and are available from Digi-Key to order today! See New Product Express at www.digikey.com/newproductexpress www.digikey.ca/analogdevices-mcu 14
Introducing a Second MCU to Embedded Designs by Nicholas Cravotta There are numerous reasons to add a second MCU to your design and numerous errors to avoid once you do. This article considers the arguments and options while pointing out the pitfalls along the way. With the wide variety of processors available today, there are a great many reasons why you may find it to be a more cost-effective choice to add new features to an application by introducing a second microcontroller (MCU) or microprocessor (MPU) to your design rather than trying to perform every task on a single, higher performance processor: • Cost: Migrating to a higher performance system MPU can have a higher cost differential than adding an 8- or 16-bit MCU to take on the added load. • Power: Rather than expend the power to have the main application processor continuously turn itself on to perform a relatively simple operation such as monitoring a sensor bank or checking if a key has been pressed, an 8-bit processor can be introduced to perform these tasks. In essence, the 8-bit processor serves as a “power gate” by letting the main processor sleep and waking it only when an event occurs that requires its attention. This is especially effective with resistive and surface capacitive touchscreens. • Determinism: User interface (UI) functions involving compute intensive tasks such as animation or audio can stress the real-time deterministic behavior of a system. Rather than risk the reliability of critical tasks such as motor control, a second MCU can assume all “real-time” UI responsibilities. • Diversity: Many systems can benefit from a modular design. For example, a display module can be implemented with a different processor to provide additional graphics, or streaming video capabilities. By taking a modular approach, the main application code does not need to be changed to add new features to the system or to support different models. • Simplicity: A product line may offer a wide variety of options. For example, a product may have four screens, three keyboards, and three connectivity options. When a single processor is used, the design team has to maintain, test, and verify a separate code version for each possible variant (4x3x3=36 distinct variants). When a secondary processor is used to implement a new function, maintenance is required only for each option (4+3+3=10). Note that with the first option, the entire system needs to be tested and verified with every variant, a complex and time-consuming process. When using the second option, the main application code only needs to be verified once. Each of the options can be verified separately and with significantly less complexity. • Conservation of I/O: An MCU can appear to be several devices over an interface by responding to several addresses. For example, the main application processor could issue a command to turn on a fan which is intercepted by an MCU serving as a virtual hub. This is an effective way to conserve I/O on the main application processor since only one communication peripheral is required to read and control multiple devices. • Certification: Changing the user interface or introducing a new interface like Wi-Fi to the main system requires the entire design to be recertified for some markets. Implementing these functions as an add-on module with a separate processor simplifies the recertification process, significantly accelerating both development and time-to-market. UART, I 2 C, and SPI There are many options available for interconnecting processors. The most basic interfaces used for this purpose are Universal Asynchronous Receiver-Transmitter (UART), Inter-Integrated Circuit (I 2 C), and Serial Peripheral Interface (SPI). Today, many processors offer hardware and software support for one or more of these interfaces. For example, STMicroelectronicss’ STM32 Cortex-M3 32- bit processors and 8-bit STM8L MCUs support all three. Alternatively, Cypress’ PSoC family of programmable system-on-chip processors have analog and digital blocks which can be configured to provide multiple instances of each of these interfaces, allowing the interface mix to be altered as required for different target markets. The question becomes how many interfaces you’re going to need. A UART operates up to 250 kbps, compared to 100 to 400 kbps for I 2 C. SPI, which supplies its own clock, can operate at speeds over 1 Mbps. A UART link can typically be implemented in software using an interrupt-based driver, so long as the driver doesn’t place too much load or latency on the processor based on the application’s needs. An I 2 C master can often be implemented in software, but a slave needs to www.digikey.ca/microcontroller 15
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: The thermistor used in the circuit
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
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Page 29 and 30: DHCP client The Dynamic Host Config
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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 and 42: Examples of deeply embedded, Intern
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Page 45 and 46: Table 1: Reflex producers. Module R
Page 47 and 48: The function PRS_ScanChannel(TIMER_
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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
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Microcontroller Solutions TechZone Magazine, April 2011 - Digikey

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