Crossbow: Smarter Sensors in Silicon Johann Ammerlahn

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 2 Crossbow Platform Review Overview and Goals History Design Approach Current System –Hardware –Software Future Directions

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 3 Overview and Goals Big Idea: Ubiquitous sensing How? –Necessarily “cheap” This is the military. Cheap is relative. –Necessarily small (more survivable, low profile, etc.) –Necessarily many (economies of scale, higher measurement granularity, lower power comms, etc.) –Necessarily robust Common case: no maintenance

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 4 Crossbow Mote History $$ + Network Embedded Systems Technology Program

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 5 Hardware Development Cycle

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 6 Current Design Analysis: Mica Series Integrate sensors, computation and communication in single unit –Basic board has radio, processor, memory –Sandwich sensor boards in layers –“Just like the rock…great cleavage” Open-source hardware/software concept –Software is TinyOS (TOS) and TinyDB (TDB) –Hardware design and Intel networking technology is licensed to Crossbow Modular design allows fast development

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 7 Available Mote Designs: MICA Crossbow 2 nd generation wireless sensor, 4 th from Berkeley Labs Atmel ATMEGA103/128L –4 Mhz 8-bit CPU –128KB Instruction Memory –4KB SRAM and EEPROM 4 Mbit flash ( AT45DB041B) –SPI interface –1-4 uj/bit r/w RFM TR1000 Radio (916/433 MHz) –50 kb/s – ASK –Focused hardware acceleration –1 to 300 ft. range, RSSI 51-pin connector –Analog ADC & comparators, I 2 C, SPI, interrupts, PWM, ext. SRAM, UART $ depending upon configuration

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 8 Available Mote Designs: MICA Atmega103 Microcontroller TR 1000 Radio Transceiver 4Mbit External Flash 51-Pin I/O Expansion Connector Power Regulation MAX1678 (3V) DS2401 Unique ID 8 Analog I/O 8 Programming Lines SPI Bus Coprocessor Transmission Power Control Hardware Accelerators Digital I/O Three low-power modes –Idle: Processor is turned off –Power Down: Everything but the watch-dog is turned off –Power Save: Only asynchronous timer powered on 100 mW power consumption –Processors, radio, typical sensor load 30 uW power consumption –All components asleep

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 9 Available Mote Designs: MICA2 Crossbow 3 rd generation wireless sensor Design changes to MICA: Processor now offers standalone boot-loader New radio (Chipcon 1000) –500 to 1000 ft. range, 38.4 Kbaud –Better noise immunity, linear RSSI –FM modulated (vs Mica AM) –Digitally programmable output power –Built-in Manchester encoding –Software programmable freq. –hopping within bands Tiny OS v improved network stack, debugging Wireless remote programming 512 Kb serial flash

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 10 Available Mote Designs: MICA2DOT Crossbow 3 rd generation wireless sensor Similar feature set to MICA2 Degraded I/O capabilities: 18 pins vs. 51 –6 analog inputs, digital bus, serial or UART Integrated temperature and battery voltage sensors, status LED Battery is 3V coin cell instead of AA x 2 25 mm diameter, 6 mm height Compatible with MICA2

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 11 Next Generation Mote: Spec Single-chip mote 2 mm x 2.5 mm RISC core 3k Memory 8-bit on-chip ADC FSK 19.2 kbps RF transmitter Paged memory SPI, RS232 compatible UART 4-bit input/4-bit output port Hardware support for comms encryption Hardware OEM costs: Under $1 in quantity (w/o antenna and sensors)

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 12 Next Generation Mote: Spec (Cont.)

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 13 Sensor & External Modules Each sensor has individual power control MTS300 –Light, temperature, acoustic, sounder MTS310 –2-axis accelerometer, 2-axis magnometer, MTS300 feature set MTS101 –Thermistor, light sensor/photocell, 24-point general prototyping area MDA500 –Connects MICA2DOT I/O signals to thru holes WSC100 –Four-channel “analog” (12-bit digital, 100hz) Bluetooth radios –Single module dedicated to either input or output –100 ft range

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 14 Operating System: TinyOS Tiny Microthreading Operating System –Tiny - 4k OS + program memory limit –Microthreading - processor directly handles almost all data (radio, sensors, etc.) –OS - allows platform for future development - convenient abstractions for hardware Designed to do the job fast and then turn off everything allowed Open source

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 15 Design Considerations Make best use of most constrained asset: battery power Network self-configuration –Manage complexity, respond to unplanned events Sensor self-configuration (?) –“Glue and go” Real-time –Limited buffering available Network robustness and maintenance –Multiple points of failure, self-healing ability Heterogeneous end environments –Application specific rather than general purpose (?) –Fast creation of efficient, specific applications w/o too much HW-specific nastiness

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 16 Example Software Layer Structure RFM Radio byte i2c Temp photo Messaging Layer clocks bit byte packet Radio Packet Routing Layer sensing application application HW SW ADC messaging routing UART Packet UART byte

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 17 Example Memory Allocation

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 18 Example Utilization: Radio Receive Components Packet reception work breakdown Percent CPU UtilizationEnergy (nj/Bit) AM 0.05%0.20%0.33 Packet 1.12%0.51%7.58 Radio handler 26.87%12.16% Radio decode thread 5.48%2.48%37.2 RFM 66.48%30.08% Radio Reception Idle-54.75%- Total %

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 19 TinyOS: Programming Structural VHDL puts the pieces together –Schematics are (usually) easier to put together and understand than code –Industry standard design model –Scripts take VHDL description and compile the resultant code base Components are aggregated and easily reused Low-level component software written In C and/or assembly –But, this is largely hidden from view for standard modules

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 20 TinyOS: Example Code /* Messaging Component Declaration */ //ACCEPTS: char TOS_COMMAND(AM_SEND_MSG)(char addr,char type, char* data); void TOS_COMMAND(AM_POWER)(char mode); char TOS_COMMAND(AM_INIT)(); //SIGNALS: char AM_MSG_REC(char type, char* data); char AM_MSG_SEND_DONE(char success); //HANDLES: char AM_TX_PACKET_DONE(char success); char AM_RX_PACKET_DONE(char* packet); //USES: char TOS_COMMAND(AM_SUB_TX_PACKET)(char* data); void TOS_COMMAND(AM_SUB_POWER)(char mode); char TOS_COMMAND(AM_SUB_INIT)();

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 21 TinyDB: Overview Imposes SQL-like querying ability on nodes Treats distributed network like a database (!) Allows specification of which data should be sent, update rate, etc. Filters and aggregates before displaying on PC screen (Java interface) Saves bandwidth and power by allowing nodes to only transmit requested data Graphical query-builder Download self-configuring runtime to motes, no C coding

6/9/2015 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 22 Crossbow Motes Conclusion Crossbow motes are very cool Probably cheap enough for us to buy a couple for playing with? –Otherwise, maybe just TinyOS emulation? Sensor Hardware –Cheap, publicly-available, modular, integrated, power-efficient, extensible, tiny Sensor Software –Free, open-source, modular, abstract, power- efficient, extensible, small