System on a Chip (SoC) Lin Zhong ELEC424, Fall 2010

Photolithography

1969

Ivan Sutherland won Turing Award in 1988 for his Ph.D. work in

“System on board” 6

“System on board” (Contd.) 7

Multiple Chip Modules (MCM) Intel Pentium D, Core 2 Quad 8 IBM POWER5 (2004) MCM, used in IBM system p servers, four dual core processors + four L3 caches Wikipedia.org

System in Package (SiP) Siemens SX66 PDA Phone Audiovox PPC6601KIT 32MB 400MHz Source: Intel.com 9

System-on-a-chip (SoC): TI OMAP 10

System-on-a-chip (SoC): TI MSP Functional block diagram

Inside a CPU (Micro-architecture) IBM POWER5 die photo (2004) FXU: fixed-point execution unit ISU: instruction sequencing unit IDU: instruction decode unit LSU: load/store unit IFU: instruction fetch unit FPU: floating-point unit MC: memory controller 12 Sinharoy et al 2005

Components of SoC Processors Clock generator Flash memory & controller DMA & controller Digital I/O modules Programming interface Interconnection 13

Embedded processors Microprocessor (32bit beyond) – ARM, MIPS, PowerPC, SuperH – Usually very modern architectures – ARM: Most popular 32bit embedded processor (75%) Assignment: read “ARM architecture” from Wikipedia Microcontroller (4-16bit) – Harvard architecture – 8051 (8bit), PIC (8bit), AVR from Atmel (8bit) – MSP430: 16-bit RISC, von Neumann architecture 14

Clock generator Resonant circuit + amplifier Resonant circuit (Oscillator) – Crystal oscillator (>2x10 9 /yr) ~10KHz to ~10MHz Quartz, ceramics (low cost, low accuracy), surface acoustic wave (SAW) quartz crystal (expensive, accurate) Real-time clocks – KHz (2 15 ), MHz (2 22 ) Application-specific – MHz (4 x MHz, CDMA baseband frequency)…… 15 Res A

LC/RLC circuit Ring oscillator – Application other than oscillator? Voltage-controlled oscillator (VCO) – Varicap: variable capacitance diode (tuning diode) – Phase-locked loop for high-speed clock (next slide) – Frequency scaling of IC for energy saving Oscillator (Contd.) 16

High-speed clock from a master oscillator Digital PLL Clock generation, recovery, synchronization – Digital computing, RF communication Phase-locked loop (PLL) 17 Phase- frequency detector Master oscillator VCO Frequency divider (N) voltage

MSP430 clock modules Clock sources – External oscillators Low- oscillator (LFXT1CLK): usually KHz (RTC) Optional high-frequency oscillator (XT2CLK) – Internal digitally controlled oscillator (DCO) (DCOCLK) (power hungry) Clock signals – Auxiliary clock: divided LFXT1CLK (1, 2, 4, 8) For low-power standby – Master clock: any source, divided by 1, 2, 4, or 8 – Sub-system clock: XT2CLK or DCOCLCK, divided by 1, 2, 4, or 8 18

DCO (Contd.) Ring oscillator with RC-type characteristics Software controllable – On/Off – Frequency – External resistor allows low temperature impact, higher frequency Impacted by temperature, supply voltage, and process variations (inter-chip variations) 19 8 internal and 1 external resistors

Flash Memory and Controller Non-volatile, semiconductor memory – Limited # of erase cycles  wear leveling NOR Flash: slow write/erase, random access – ROM replacement NAND Flash: faster write/erase, block access, denser, more enduring – Harddisk replacement 20

MSP430 Flash memory controller NOR flash (for program) – No need for wear leveling (100K to 1M erase cycles) In-system programmable (ISP) – Self programming, program via wireless Programming through JTAG, UART (Bootstrap loader, BSL) 21

Digital I/O Modules USART – Universal synchronous/asynchronous receiver/transmitter – Asynchronous: UART – Synchronous: SPI, I2C UART (2-4 wires) – Easily work with RS-232 (serial port), modem, Bluetooth (Serial Port Profile) – Baud rate, # of data bits, optional parity bit, flow control 22

MSP430 UART Two UART ports, each two pins Support interrupt No hardware flow control <200Kbps 23

Serial interfaces Inter-Integrated Circuit (I 2 C) – Two wires – Standard mode: 100Kbps – Fast mode: 400Kbps – System management bus (SMBus): 100Kbps Serial Peripheral Interface (SPI) – 4 wires: Clock, Chip Select, In and Out – Low-megahertz data rate wikipedia.org

Universal Serial Bus (USB) Replacing all serial/parallel ports – All phones in China use USB for power Host vs. device USB 1.0: low-speed, 1.5Mbps – Human interface devices – 1.5A power supply – USB 1.1: full-speed, 12bBps USB 2.0: high-speed, 480Mbps – Storage devices, Wi-Fi cards etc. – 900mA power supply USB 3.0: super-speed, 4.8Gbps

Analog I/O Analog-digital conversion (ADC) – Voltage measurement – Sensing the world through voltage XXX  voltage Digital-analog conversion (DAC) – Actuator 26

ADC Resolution: how many bits for “D”? – 24bits max – MSP : 12 bits Sampling rate: how fast? – MSP430: up to 200Ksps Accuracy – Quantization error etc. 27

Interrupt Polling vs. interrupt Non-maskable vs. maskable Nested interrupt 28 Interrupt handler Save context Retrieve context

Interrupt Programmable interrupt controller (PIC) – Prioritizing multiple sources – Offloading the CPU 29 PIC CPU Interrupt Interrupt vector Interrupt sources (external devices)

Exceptions, signals, & interrupts Exceptions – Any disruption of normal execution to execute special instructions Signals – Inter-process communication Interrupt – Asynchronous exception introduced by external hardware 30

Timer Count time – Keep time How many cycles have elapsed – Measure time Whether a given period of time elapsed Generate interrupt 31 Capture register Clock Compare register Comparator Interrupt

Direct memory access (DMA) Free CPU from data transfer Multiple channels, master bus, interrupt CP when done 32

DMA (Contd.) Character mode Block mode 33

Power-saving mechanisms Frequency scaling (slow down) – DCO Power saving modes 34

Miscellaneous Pulse-width modulation (PWM) – Applications: power delivery (charging, light, motor), sound synthesis Watchdog timer – Reset system under fault Brownout reset – Reset system when supply voltage low 35