A Comparative Analysis of Conventional 8051 Microcontroller with Modern Ultra Low Power MSP430 #1
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Nishit Chittora, Akshay Nigam, Pankaj Chaudhary, Saurabh Porwal
[email protected],
[email protected],
[email protected],
[email protected] 1, 2, 3
Electronics & Communication Engineering Department,
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Sr. Lecturer, Electronics & Communication Engineering Department, #
Geetanjali Institute of Technical Studies, Udaipur
Abstract— Abstract— Computational tools and computing machines were always the attraction and motivation for the technological implementation in the field of industrial and domestic products. The popularity of microcontroller is ever increasing, as fuelled by the advances in the semiconductor industry. They are embedded in almost any device connected to power or battery. The limitations of digital electronics have almost vanished today, due to emergence of these varieties of powerful microcontrollers. By reducing the size and cost compared to a design that uses a separate microprocessor, memory, and input/output devices, microcontrollers make it economical to digitally control even more devices and processes consuming less power. In this paper featural characteristic of latest processor MSP430 is highlighted. These processors utilize common, integrating analog components to control nondigital electronic systems. A comparison is done among different features of the ultra low power MSP430 with the conventional 8051 microcontroller. Broad application areas and advantages of MSP430 microcontroller over 8051 are also illustrated and reviewed in terms of power consumption and additional on-chip components.
office machines, appliances, power tools, and toys. The first industry efficient microcontroller Intel MCS-51 is based on Harvard architecture. It is single chip microcontroller microcontroller (µC) series which was developed by Intel in 1980 for use in embedded syste s ystems. ms. Intel's original versions were popular in the 1980s and early 1990s, but has today largely been superseded by a vast rang e of faster and/or functionally enhanced 8051compatible devices manufactured by more than 20 independent manufacturers. Intel's original MCS-51 family was developed using NMOS technology, but later versions, identified by a letter C in their name (e.g., 80C51) used CMOS technology and were less powerhungry than their NMOS predecessors. predecessors. This made them more suitable for battery-powered devices. However, as the need has grown, a desire to control more number of hip components has increased, which seeks more power.
— Microcontroller, Keywords — Microcontroller, 8051, MSP430, Architectural features, low-power modes. I. I NTRODUCTION A microcontroller is a functional computer system-on-a-chip. It contains a processor core, memory and programmable input/output peripherals. They consume relatively little power (milliwatts), and will generally have the ability to retain functionality while waiting for an event such as button press or interrupt. As they are programmable, its programs must fit in the available on-chip program memory to reduce its cost. Since processors interpret and process digital data, i.e. only 1s and 0s only, they won’t be able to do anything with the analog signals that may be being sent to it by a device. So as an A/D converter is used to convert the incoming data into a form that th e processor processor can recognise. r ecognise. Microcontrollers are now used in all automatically controlled products and devices, such as automobile engine control systems,
Fig. 1 Basic block diagram of microcontroller
The Texas Instrument’s Instrument’s MSP430 is a mixedsignal microcontroller microcontroller family from Texas Instruments. Built around a 16-bit CPU, the MSP430 is designed for low cost, and specifically, specifically, low power consumption embedded applications. The MSP430 is particularly well suited for metering, wireless radio frequency engineering (RF), or battery-powered battery-powered
In MSP430 a 16-bit RISC CPU, peripherals mode, the processor can achieve current in the and flexible clock system are combined by using microamps while still monitoring its inputs. The a Von-Neumann common memory address bus modes vary the degree to which the processor is (MAB) and memory data bus (MDB). Partnering aware of its surroundings and the clocks that the a modern CPU with modular memory-mapped processor keeps running. Further a useful analog and digital peripherals, the MSP430 offers property of the MSP430 is that its recovery time solutions for all mixed-signal applications. from some low-power modes is fast enough to meet the response times of interrupts. III. CHARACTERISTIC FEATURES A. 8051 Microcontroller Key Features
The 8051 architecture provides many functions (CPU, RAM, ROM, I/O, interrupt logic, t imer, etc.) in a single package 1. 8-bit ALU, Accumulator and 8-bit Registers, hence it is an 8-bit microcontroller. microcontroller. 2. 8-bit data bus – It can access 8 bits of data in one operation 3. 16-bit address bus – It can access 216 memory locations – 64 KB (65536 locations) each of RAM and ROM 4. On-chip RAM – 128 bytes (data memory) Fig. 2 Block diagram of MSP430 microcontroller 5. On-chip ROM – 4 KByte (program memory) 6. Four byte bi-directional input/output port II. POWER MANAGEMENT 7. UART (serial port) Power management would be much simpler if 8. Two 16-bit Counter/timers all portable electronics requires the same operating voltage. In recent years, power 9. Two-level interrupt priority 10.Two 10. Two power saving modes consumption has moved to the forefront of digital IC development concerns. The combination of B. MSP430 Microcontroller Key Features higher clock speeds, greater functional MSP430 offers 200+ ultra-low power integration, and smaller process geometries has microcontrollers devices. Each device features a contributed to significant growth in power flexible clocking system. MSP430 ensures that density. Furthermore, with every new process the application only uses the appropriate clocks generation, leakage power consumption increases and peripherals that are needed to perform the at an exponential rate. task at hand. Several features make the MSP430 Most parts have a shutdown or sleep mode suitable for low-power and portable applications, available that will reduce th e current consumption which are hardly present in 8051 microcontroller: of the component considerably. In general, digital 1. MSP430 has low power consumption, parts consume significant current when their a. It takes only 0.1µA for RAM data transistors switch because of the charging and retention. discharging of the internal capacitances of the b. Requires 0.8 µA for real time clock transistors. Analogue integrated circuits also mode operation. support shutdown modes to reduce power c. And 250 µA per MIPS (Machine consumption. It is important to note that when a Instructions per Second) at active device is in shutdown mode, power and ground operation voltages are still powered and connected to the 2. It works on low operating voltages ranging device. from 1.8 V to 3.6 V in different operating In order to shutdown most integrated circuits, modes. all that is required is a shutdown or sleep pin to be 3. The port has low leakage current typically asserted properly. Other devices require a less than 50nA. shutdown command to be issued over the bus. 4. These controllers can be put easily from The primary disadvantages of shutdown modes, active mode to low-power mode by apart from the fact that the device is in operative is controlling bits in the status register. These that recovering back into normal operating modes supports several low-power modes, can impose a significant delay. depending on how much of the device should In battery operated electronic devices, the remain active and how quickly it should energy required to execute given tasks set is one return to full-speed operation. of very important parameters. The modern 5. MSP430 contain specialized on-chip MSP430 microcontroller provides a number of analogue components for various types of methods to reduce microcontroller power measurement like requirements by selecting among the various
b.
12-bit dual Digital-to-Analog Converter (DAC) c. Comparator-gated timers to count for events. d. Operational Amplifiers for comparison. comparison. e. Supply Voltage Supervisor (SVS) to generate a system reset (POR) when the external supply voltage drops below a user-selectable user-selectable threshold. 6. These controllers can drive directly many 2 portable devices such as USART, IC/SPI Universal Serial Interface and LCD displays. 7. The architecture of these devices is 16-bit RISC (Reduced Instruction Set Computing) with following features: a. Instructions processing done on any bits, bytes or words. b. Compact core design which reduces power consumption and cost. c. Has 51 instructions (27 core + 24 emulated). d. Supports 7 addressing modes. e. Has extensive vectored-interrupt capability. Any interrupt can wake up the MSP430 from low-power mode to active mode and transfer the routine of the program to vector locations causing that interrupt. 8. Availability of wide choice of clocks with different sources. EAL-TIME CAPABILITY WITH ULTRA-LOW IV. R EAL POWER CONSUMPTION
The design of the MSP430 was driven by the need to provide full real-time capability while still exhibiting extremely low power consumption. Average power consumption is reduced to the minimum by running the CPU and certain other functions of the MSP430 only when it is necessary. The rest of the time (the majority of the time), power is conserved by keeping only selected low-power peripheral functions active. But to have a true real-time capability, the device must be able to shift from a low-power mode with the CPU off to a fully active mode with the CPU and all other device functions operating n ominally in a very short time. This was accomplished primarily with the design of the system clocks. The MSP430 has three separate clocks that can run as quickly as 16 MHz in particular conditions. The reason three clocks instead of just one or even two is to compromise between systems that need speed and the ability to minimize power consumption, one of the real hallmarks of the MSP430. Faster clocks clocks consume more power, so to really reduce the power used we need slower slower clocks. But some functions functions need to respond and conclude quickly, so we also need fast clocks. We can design around around the use of a single clock, but having the flexibility of three is powerful. The three clocks available in BCS+
A. MCLK: This is the Master Clock, the one that drives the processor and times the commands in your program. program. This is typically typically a high frequency clock, but can be configured for low frequencies if needed. B. SMCLK: The Sub-Main Clock is a secondary clock that is often used by other peripherals. It can be the same frequency as MCLK or different, depending on the application. C. ACLK: The Auxiliary Clock is usually timed outside the MSP430 and is typically used for peripherals. Often, this is a low frequency frequency clock, but can also be used at high frequencies when desired.
All of the techniques that improve code efficiency will improve power efficiency. Increasing clock speed will not yield similar power savings because faster execution increases power consumption. Similarly, unused peripheral modules on the processor should be de-activated to save power. V. MSP430 APPLICATION OPERATING MODES MSP430 has six operating modes including the active mode, each with different power requirements. Three of these modes are important for battery-powered battery-powered applications: A. Active mode In this mode the CPU and other device functions run all the time. It is used for calculations, decision-making, I/O functions, and other activities that require the capabilities of an operating CPU. All of the peripheral functions may be used, provided that they are enabled. B. Low power mode 3 (LPM3)
This is the normal mode for most applications during 99% to 99.9% of the time. This mode is also called done mode or sleep mode. This mode is most important for battery-powered applications. The CPU is disabled, but enabled peripherals stay active. The basic timer provides a precise time base. When enabled, interrupts restore the CPU, switch on MCLK, and start normal operation. C. Low power mode 4 (LPM4)
This mode is typically used during storage. This mode is also called off mode. It is used if the absolute lowest supply current is necessary or if no timing is needed or desired (no change of the RAM content is allowed). This is normally the case for storage preceding or following the calibration process. process. VI. APPLICATIONS Within the MSP430 platform, it includes 5 generations of ultra-low power, highly integrated microcontrollers spanning over 200 devices. It
to help developers find the right microcontroller VII. CONCLUSION for various applications. MSP430 applications fall One of the most important quality standards into two main classes, depending on the power for battery powered devices is battery life. supply: Handheld medical tools, electricity meters, For AC power-driven applications such as personal digital assistants, and a goal of the electricity meters and AC-powered controllers the designer and programmer is to lower the power microcontroller needs to be active at all times. use of the embedded system to negligible levels. The low current consumption of the MSP430 In designing battery powered devices, savings can when active (900 µA @ 5V & f C = 1 MHz) puts it be gained from the choice of electronic well within the typical low-power category now components, the arrangement of components, and which is currently < 40 mA. the software on the design. The MSP430 supports For battery-powered applications such as gas various low power modes thus we can conclude meters, water flow meters, heat volume counters, that, the ultra-low power mixed-signal data loggers, and other controller and remote microcontrollers from TI provides the ultimate metering tasks power consumption is the key solution for a wide range of low power and issue since operation from a single battery for 10 portable applications. years or longer is often required. The average To enable the adoption of advanced lowcurrent drawn by the MSP430 needs to be in the power techniques by mainstream users, the range of the self discharge current of the battery, MSP430 fulfils the need for a design flow which approximately 1 µA to 3 µA. holistically addresses the architecture, design, Thus the major applications of MSP430 are in verification, and implementation of low-power Utility Metering, Portable Medical and designs. instrumentation, Low-power Wireless The major advantage of MSP430 is that it Application, Intelligent Sensing, Communication requires very low input power supply for its and telecom, Consumer Electronics, Security operation, Further more it has inbuilt ADC and Systems, Energy and lightening, Space Avionics DAC which are not present in 8051 and Defence, Defence, Transportation Transportation Automotive. Automotive. microcontroller. The MSP430's DMA allows data The conventional 8051 microcontrollers are transfers from one address to another without generally used in Home Appliances, Office CPU intervention, across the entire address range. Accessories, Portable electronic gadgets, This features up to three independent transfer biomedical instrumentation, Automobile channels. industries, mission critical application, solar panels etc. EFERENCES R EFERENCES [1]
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TABLE 1 COMPARISON BETWEEN 8051 AND MSP430 Features
8051
MSP430
CPU width Architecture Architectu re
8-bit 8-bit internal data bus width and 16-bit internal address bus with Harvard architecture 8-bit and 16-bit CISC 5 Fixed
16-bit Flexibility of 16 data and address fullyaddressable, single-cycle 16-bit CPU registers
Register Sets Type of processor Addressing modes Clocking System
16-bit CPU registers RISC 7 Flexible Clocking System with MCLK, ACLK and SMCLK
Instructi on sets Timers
255 instructions 2 to 3
Watch Dog Power requirement Power dissipation On-chip components
No 5 Volt 1.5Watt Not Available
ADC and DAC
External interface required
On-chip wireless features DMA Low power modes Programming Interface Cost
Not Available
Not Available Two mode available Aging RS232 Comparatively Comparativel y high
51 instructions instructi ons (27 core + 24 emulated) Several timers few of which have capture compare modes Yes 1.8-3.6 Volt 4.5mW Available on-chip – USB, LCD, LCD_A controllers, Software RTC Module Available on-chip 10, 12 and 16-bit different ADCs in specific devices Available Available upto 3 to 8 channels Five modes available 4-wire JTAG and Spy Bi-wire Bi-wir e interface Low-cost, lower-end applicati ons. Ideal for high-volume/Low-cost designs (25 cents)
AUTHORS Saurabh Porwal is a Sr. Lecturer in the department of Electronics & Communication Engineering Geetanjali Institute of Technical Studies, Udaipur. He has a professional experience of working with Microcontrollers, Automation & Instrumentation parts. He has guided several projects based on Embedded System design starting from hardware designing to complete logic development, one of which got sponsored from Department of Science and Technology, Rajasthan. He has contributed and presented several papers in various reputed International & National Conferences & Seminars of IEEE, IETE & IEI. He has acted as co-editor in the Book of Proceedings of the IEEE National Conference NCACA-2009 and also authored a text book on Embedded System Design for students of undergraduate level.
Akshay Nigam is pursuing his technical graduation in Electronics and Communication Engineering at Geetanjali Institute of Technical Studies, Udaipur. He has undertaken training on PLC & DCS systems in Videocon Industries Limited. He has also attended IEEE International Workshop on RF and Microwave. His subjects of interest are Microcontroller, Wireless Communication and Digital Signal Processing. Currently he is working on DTMF based Telephone Remote Control and Automation.
Pankaj Chaudhary is pursuing his technical graduation in Electronics and Communication Engineering at Geetanjali Institute of Technical Studies, Udaipur. Apart from this he has also designed and developed Nishit Chittora is pursuing his website of department of Electronics & technical graduation in Electronics and Communication Engineering, GITS. His subjects Communication Engineering of interest are Microcontroller, Microprocessor & at Geetanjali Institute of Digital Electronics. He is currently working on Technical Studies, Udaipur. the project Ultrasonic Range Finder based on He has undergone training in microcontroller 8051. HMT Machines Tools Ltd., Ajmer, on programmable Logic Controller. His subjects of interest are Microcontroller, Microprocessor, Control System, Robotics and Digital Electronics. He is currently working on the project Ultrasonic Range Finder based on microcontroller microcontroller 8051.
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