Crossbow Smarter Sensors in Silicon Johann Ammerlahn Crossbow

Crossbow: Smarter Sensors in Silicon Johann Ammerlahn

Crossbow Platform Review l Overview and Goals l History l Design Approach l Current System – Hardware – Software l Future 12/16/2021 Directions Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 2

Overview and Goals Big Idea: Ubiquitous sensing l How? l – 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 12/16/2021 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 3

Crossbow Mote History $$ + Network Embedded Systems Technology Program 12/16/2021 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 4

Hardware Development Cycle 12/16/2021 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 5

Current Design Analysis: Mica Series l 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” l Open-source hardware/software concept – Software is Tiny. OS (TOS) and Tiny. DB (TDB) – Hardware design and Intel networking technology is licensed to Crossbow l Modular design allows fast development 12/16/2021 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 6

Available Mote Designs: MICA l l l Crossbow 2 nd generation wireless sensor, 4 th from Berkeley Labs Atmel ATMEGA 103/128 L – 4 Mhz 8 -bit CPU – 128 KB Instruction Memory – 4 KB SRAM and EEPROM 4 Mbit flash (AT 45 DB 041 B) – SPI interface – 1 -4 uj/bit r/w RFM TR 1000 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 $100 -400 depending upon configuration Graphics Courtesy Crossbow 12/16/2021 Technologies, Inc. and Berkeley Labs 7

Available Mote Designs: MICA l 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 51 -Pin I/O Expansion Connector Digital I/O DS 2401 Unique ID l 100 m. W power consumption 8 Analog I/O 8 Programming Lines Atmega 103 Microcontroller Transmission Power Control l Hardware Accelerators 30 u. W power consumption – All components asleep TR 1000 Radio Transceiver SPI Bus – Processors, radio, typical sensor load Coprocessor 4 Mbit External Flash Power Regulation MAX 1678 (3 V) 12/16/2021 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 8

Available Mote Designs: MICA 2 Crossbow 3 rd generation wireless sensor l Design changes to MICA: l Processor now offers standalone boot-loader l New radio (Chipcon 1000) l – – – – 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. 1. 0 - improved network stack, debugging l Wireless remote programming l 512 Kb serial flash l 12/16/2021 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 9

Available Mote Designs: MICA 2 DOT l l l l Crossbow 3 rd generation wireless sensor Similar feature set to MICA 2 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 3 V coin cell instead of AA x 2 25 mm diameter, 6 mm height Compatible with MICA 2 12/16/2021 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 10

Next Generation Mote: Spec l l l Single-chip mote 2 mm x 2. 5 mm RISC core 3 k Memory 8 -bit on-chip ADC FSK 19. 2 kbps RF transmitter Paged memory SPI, RS 232 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) 12/16/2021 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 11

Next Generation Mote: Spec (Cont. ) 12/16/2021 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 12

Sensor & External Modules Each sensor has individual power control l MTS 300 l – Light, temperature, acoustic, sounder l MTS 310 – 2 -axis accelerometer, 2 -axis magnometer, MTS 300 feature set l MTS 101 – Thermistor, light sensor/photocell, 24 -point general prototyping area l MDA 500 – Connects MICA 2 DOT I/O signals to thru holes l WSC 100 – Four-channel “analog” (12 -bit digital, 100 hz) Bluetooth radios – Single module dedicated to either input or output Graphics Courtesy Crossbow – 100 ft range 12/16/2021 Technologies, Inc. and Berkeley Labs 13

Operating System: Tiny. OS l Tiny Microthreading Operating System – Tiny - 4 k 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 l Open source l 12/16/2021 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 14

Design Considerations Make best use of most constrained asset: battery power l Network self-configuration l – Manage complexity, respond to unplanned events l Sensor self-configuration (? ) – “Glue and go” l Real-time – Limited buffering available l Network robustness and maintenance – Multiple points of failure, self-healing ability l Heterogeneous end environments – Application specific rather than general purpose (? ) – Fast creation of efficient, specific applications w/o too much HW-specific nastiness 12/16/2021 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 15

Example Software Layer Structure sensing application Routing Layer routing Messaging Layer messaging packet byte bit 12/16/2021 Radio Packet UART Packet Radio byte UART byte RFM clocks Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs photo ADC Temp SW i 2 c HW 16

Example Memory Allocation 12/16/2021 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 17

Example Utilization: Radio Receive Components Packet reception work breakdown Percent CPU Utilization Energy (nj/Bit) AM 0. 05% 0. 20% 0. 33 Packet 1. 12% 0. 51% 7. 58 26. 87% 12. 16% 182. 38 5. 48% 2. 48% 37. 2 66. 48% 30. 08% 451. 17 Radio Reception - - 1350 Idle - 54. 75% - 100. 00% 2028. 66 Radio handler Radio decode thread RFM Total 12/16/2021 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 18

Tiny. OS: Programming l 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 l Low-level component software written In C and/or assembly l – But, this is largely hidden from view for standard modules 12/16/2021 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 19

Tiny. OS: 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)(); 12/16/2021 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 20

Tiny. DB: 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, Graphics Courtesy Crossbow no C coding 12/16/2021 Technologies, Inc. and Berkeley Labs 21

Crossbow Motes Conclusion Crossbow motes are very cool l Probably cheap enough for us to buy a couple for playing with? l – Otherwise, maybe just Tiny. OS emulation? l Sensor Hardware – Cheap, publicly-available, modular, integrated, power-efficient, extensible, tiny l Sensor Software – Free, open-source, modular, abstract, powerefficient, extensible, small 12/16/2021 Graphics Courtesy Crossbow Technologies, Inc. and Berkeley Labs 22