Embedded Systems Systems Embedded Computer Computer Embedded Embedded Architecture Architecture Systems Systems Jakob Engblom, PhD Jakob Engblom, PhD Uppsala Unive University rsity & Virtutech Inc. & Virtutech Inc. Uppsala virtutech virtu virtutech virtutech tech jakob.engblom@it.uu.se jakob.engblom@it.uu.se jakob@virtutech.com jakob@virtutech.com 14 Nov 2003 Embedded Computer Architecture 2 Embedded Systems Embedded Systems Embedded Systems Embedded Systems Now what Now what is this is this elephant thing? elephant thing ? You’ You ’re re all all � “ “A computer that doesn A computer that doesn’ ’t t � wrong wrong, it is a , it is a fan! fan! look like a computer” ” look like a computer No, a No, a wall! ! wall It is a It is a � Interacts with world Interacts with world � snake! snake ! � Primitive or no user interface Primitive or no user interface � � Part of other products Part of other products � No, it is a No, it is a treetrunk! treetrunk ! No, a No, a pillar! pillar! 14 Nov 2003 Embedded Computer Architecture 3 14 Nov 2003 Embedded Computer Architecture 4
Embedded Systems Embedded Systems Processor Market Processor Market Single purpose products Embedded = most = most processors! processors! � Single purpose products � Embedded � � Not general purpose general purpose like desktop PCs like desktop PCs 200 million PC and server � Not � 200 million PC and server � � Do one thing very efficiently � Do one thing very efficiently 8000 million embedded � � 8000 million embedded � Software very important: � Software very important: � � Gives character to product Gives character to product � � Used to differentiate inside a � Used to differentiate inside a “ “platform platform” ” "Embedded" Can be changed late � Can be changed late � 98% Processor cheaper than special HW � Processor cheaper than special HW � "Desktop" Today, dominates dev cost oday, dominates dev cost � T 2% � 14 Nov 2003 Embedded Computer Architecture 5 14 Nov 2003 Embedded Computer Architecture 6 Processor Market Real- -Time System Time System Processor Market Real Timing as important as result � Processors: Processors: � Timing as important as result � � 100% � 50% of all 50% of all DSP DSP � Hard real- -time: time: � Hard real 90% 4-bit semiconductor revenue semiconductor revenue � 4-bit 8-bit 80% � Explains why everyone Explains why everyone � Hard deadlines � Hard deadlines � wants to do processors wants to do processors 70% 16-bit � Dead if missed deadline Dead if missed deadline � 32 32- -bit dominant bit dominant � 60% � 50% Worst- -case case � 30% of total 30% of total � Worst � 8-bit � semiconductors semiconductors 40% � Soft real Soft real- -time: time: � 32-bit � PC processors: PC processors: 30% � � 50% of CPU revenue 50% of CPU revenue 20% � Fuzzier deadlines Fuzzier deadlines � � 16-bit � 15% of total 15% of total 10% � Can miss some deadlines � Can miss some deadlines � 32-bit semiconductors semiconductors 0% Average- -case case � Average � AMD and Intel share it AMD and Intel share it Units Money � � 14 Nov 2003 Embedded Computer Architecture 7 14 Nov 2003 Embedded Computer Architecture 8
Real- Real -Time Systems Time Systems Simple Embedded Systems Simple Embedded Systems Embedded and Real- -Time Time � Embedded and Real � 8-bit Intel 8051, Synonymous? � Synonymous? � standard microcontroller Most embedded � Most embedded � Behavior, talk, embedded embedded IR communications systems are systems are real- -time time real embedded embedded real- -time time real Most real- -time time � Most real 8-bit Hitachi H8/300 � 32 kB ROM, 32 kB RAM systems are systems are real- -time time Standard microcontroller chip real embedded embedded Byte-code machine, sensor drivers, … 14 Nov 2003 Embedded Computer Architecture 9 14 Nov 2003 Embedded Computer Architecture 10 Fun App: Smart Beer Glass No Upgrades Possible Fun App: Smart Beer Glass No Upgrades Possible Capacitive Capacitive � Once a product ships Once a product ships… … � sensor for sens or for fluid level fluid level …it often cannot be serviced it often cannot be serviced � … � 8- -b bit, 8 it, 8- -pin pin 8 No download ability � No download ability PIC processor PIC processor � Contactless Cont actless No writable persistent storage � No writable persistent storage � transmission of Inductive coil for Indu ctive coil for transmission of RF ID activation No disks power and power and RF ID activation � No disks � readings & power & power readings No loader � No loader � CPU and reading coil in the Software is write- -once once � Software is write � table. Reports the level of fluid in the glass, alerts � (There are exceptions) (There are exceptions) � servers when close to empty 14 Nov 2003 Embedded Computer Architecture 11 14 Nov 2003 Embedded Computer Architecture 12
Consumer Electronics Consumer Electronics Automotive Autom otive � Multiple networks Multiple networks � � Heterogeneous Heterogeneous � � CAN for body CAN for body � multiprocessor multiprocessor electronics: 30+ nodes electronics: 30+ nodes � CAN for engine control: CAN for engine control: � � 8 8- -bit Atmel AVR for UI, games, bit Atmel AVR for UI, games, … … � few nodes few nodes � 16 16- -bit fixed bit fixed- -point TI C54 DSP for point TI C54 DSP for � � LIN for instruments LIN for instruments � GSM coding, radio interface, … GSM coding, radio interface, … � Many processors Many processors � 32 32- -bit ARM7 in Bluetooth module bit ARM7 in Bluetooth module � � � + maybe ARM7 in IRDA interface + maybe ARM7 in IRDA interface � � Up to 100 Up to 100 � � All in custom chips All in custom chips � � Large diversity in processor types: Large diversity in processor types: � � Software is large: Software is large: � � 8 8- -bit CPUs (PIC, HC08) for door locks, lights, etc. bit CPUs (PIC, HC08) for door locks, lights, etc. � � 16 MB of code in control part 16 MB of code in control part � 16 16- -bit CPUs (C167, HC11, HC12) for most functions bit CPUs (C167, HC11, HC12) for most functions � � � Plus signal processing code Plus signal processing code � � 32 32- -bit CPUs (PPC,V850) for engine control, airbags bit CPUs (PPC,V850) for engine control, airbags � � Total amount of code: 40 Total amount of code: 40- -50 MB 50 MB � 14 Nov 2003 Embedded Computer Architecture 13 14 Nov 2003 Embedded Computer Architecture 14 Automotive Timing Aspects Automotive Timing Aspects � Form follows function Form follows function � Interrupt latency Interrupt latency � � � Processing where the action is Processing where the action is � Important criterion for embedded Important criterion for embedded � � � Architecture given by application Architecture given by application � A few clock cycles at most A few clock cycles at most � � � Sensors and actuators distributed Sensors and actuators distributed � Measure of RTOS performance Measure of RTOS performance � � � Heterogeneous systems Heterogeneous systems � Real Real- -Time = predictability Time = predictability � � Many different makes of different makes of CPUs CPUs In- -order pipelines order pipelines � Many � In � � � Standardized Standardized at the at the network network/bus /bus � SRAM instead of caches SRAM instead of caches � � � Lockable caches Lockable caches � � Several small CPUs instead of one big Several small CPUs instead of one big � 14 Nov 2003 Embedded Computer Architecture 15 14 Nov 2003 Embedded Computer Architecture 16
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