PowWow
Encyclopedia
PowWow is a wireless sensor network (WSN)
mote
developed by the Cairn team of IRISA
/INRIA. The platform is currently based on IEEE 802.15.4
standard radio transceiver and on an MSP430 microprocessor
. Unlike other available mote systems, PowWow offers specific features for a very-high energy efficiency
:
platform is composed of a motherboard
including an MSP430 microcontroller
and of other daughter boards such as the radio transceiver board, the coprocessing board and some sensor and energy harvester
boards.
and hardware acceleration
to increase the energy efficiency of the network.
PowWow uses RICER protocol proposed by UC Berkeley to reduce the time spent in radio reception (RX) mode. This protocol consists in cycled rendez-vous initiated by a wake-up beacon from potential receivers. Thanks to this method, nodes are sleeping most of the time, hence saving energy.
PowWow uses a simple geographical routing protocol.
in the sense of Euclidian distance
, which provides a sequential control flow without complex state machines or full multi-threading.
PowWow is delivered as an open source
hardware and open source software under the GPL license.
Wireless sensor network
A wireless sensor network consists of spatially distributed autonomous sensors to monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants and to cooperatively pass their data through the network to a main location. The more modern...
mote
Sensor node
A sensor node, also known as a mote , is a node in a wireless sensor network that is capable of performing some processing, gathering sensory information and communicating with other connected nodes in the network...
developed by the Cairn team of IRISA
IRISA
The Institut de recherche en informatique et systèmes aléatoires is a joint computer science research center of CNRS, University of Rennes 1, INSA and INRIA, located in Rennes in Brittany...
/INRIA. The platform is currently based on IEEE 802.15.4
ZigBee
ZigBee is a specification for a suite of high level communication protocols using small, low-power digital radios based on an IEEE 802 standard for personal area networks. Applications include wireless light switches, electrical meters with in-home-displays, and other consumer and industrial...
standard radio transceiver and on an MSP430 microprocessor
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
. Unlike other available mote systems, PowWow offers specific features for a very-high energy efficiency
Efficient energy use
Efficient energy use, sometimes simply called energy efficiency, is the goal of efforts to reduce the amount of energy required to provide products and services. For example, insulating a home allows a building to use less heating and cooling energy to achieve and maintain a comfortable temperature...
:
- the MAC layer is based on an asynchronous rendez-vous scheme initiated by the receiver,
- architectural and circuit level optimizations were performed such as power managementPower managementPower management is a feature of some electrical appliances, especially copiers, computers and computer peripherals such as monitors and printers, that turns off the power or switches the system to a low-power state when inactive. In computing this is known as PC power management and is built...
, frequencyFrequency scalingIn computer architecture, frequency scaling is the technique of ramping a processor's frequency so as to achieve performance gains...
and voltage scaling and FPGAField-programmable gate arrayA field-programmable gate array is an integrated circuit designed to be configured by the customer or designer after manufacturing—hence "field-programmable"...
co-processing for low power, - the software stack is very light (5 kbytes) uses event-driven programmingEvent-driven programmingIn computer programming, event-driven programming or event-based programming is a programming paradigm in which the flow of the program is determined by events—i.e., sensor outputs or user actions or messages from other programs or threads.Event-driven programming can also be defined as an...
and is currently derived from the Protothread library of ContikiContikiContiki is a small, open source, highly portable multitasking computer operating system developed for use on a number of memory-constrained networked systems ranging from 8-bit computers to embedded systems on microcontrollers, including sensor network motes...
.
Hardware
PowWow hardwareHardware
Hardware is a general term for equipment such as keys, locks, hinges, latches, handles, wire, chains, plumbing supplies, tools, utensils, cutlery and machine parts. Household hardware is typically sold in hardware stores....
platform is composed of a motherboard
Motherboard
In personal computers, a motherboard is the central printed circuit board in many modern computers and holds many of the crucial components of the system, providing connectors for other peripherals. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple...
including an MSP430 microcontroller
Microcontroller
A microcontroller is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Program memory in the form of NOR flash or OTP ROM is also often included on chip, as well as a typically small amount of RAM...
and of other daughter boards such as the radio transceiver board, the coprocessing board and some sensor and energy harvester
Energy harvesting
Energy harvesting is the process by which energy is derived from external sources , captured, and stored for small, wireless autonomous devices, like those used in wearable electronics and wireless sensor networks.Energy harvesters...
boards.
Processing motherboard
- TI MSP430TI MSP430The MSP430 is a mixed-signal microcontroller family from Texas Instruments. Built around a 16-bit CPU, the MSP430 is designed for low cost, and specifically, low power consumption embedded applications. The architecture dates from the 1990s and is reminiscent of the DEC PDP-11.-Applications:The...
low-power microcontroller - MSP430F1612 version, 8 MHz clock
- 55KB of flash memoryFlash memoryFlash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM and must be erased in fairly large blocks before these can be rewritten with new data...
, 5KB of on-chip RAM - 330uA at 1 MHz and 2.2 V in active mode, 1.1uA in standby mode
- P1, P2 connectors for extension
- JTAG, RS232 and I2C interfaces
Radio Board
- TI CC2420 RF transceiver
- Digital direct sequence spread spectrumSpread spectrumSpread-spectrum techniques are methods by which a signal generated in a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth...
basebandBasebandIn telecommunications and signal processing, baseband is an adjective that describes signals and systems whose range of frequencies is measured from close to 0 hertz to a cut-off frequency, a maximum bandwidth or highest signal frequency; it is sometimes used as a noun for a band of frequencies...
modem - Single-chip 2.4 GHz IEEE 802.15.4 compliant
- Spreading gain of 9 dB, data rate of 250 kbps
- Digital direct sequence spread spectrum
- Hardware support for packet handling, data buffering, burst transmissionBurst transmissionIn telecommunication, the term burst transmission or data burst has the following meanings:# Any relatively high-bandwidth transmission over a short period of time...
s, data encryption, data authentication, clear channel assessment, link quality indication and packet timing information
Co-processing Board
A co-processing board can be added to the motherboard on P1, P2 connectors. This board provides dynamic voltage scalingDynamic voltage scaling
Dynamic voltage scaling is a power management technique in computer architecture, where the voltage used in a component is increased or decreased, depending upon circumstances. Dynamic voltage scaling to increase voltage is known as overvolting; dynamic voltage scaling to decrease voltage is known...
and hardware acceleration
Hardware acceleration
In computing, Hardware acceleration is the use of computer hardware to perform some function faster than is possible in software running on the general-purpose CPU...
to increase the energy efficiency of the network.
- Power Mode Management (PMM)
- Low-Power Programmable Timer for Wake-up period
- MAX6370, 8uA
- Dynamic Voltage and Frequency Scaling (DFVS)
- Programmable Clock
- LTC6930, 490uA
- 8MHz divided by 1 to 128
- Programmable DC/DC converter
- TPS62402/TPS61030
- Programmable Clock
- FPGA co-processing
- Low-power Igloo FPGA from ActelActelActel Corporation is a manufacturer of nonvolatile, low-power FPGAs, mixed-signal FPGAs, and programmable logic solutions...
- AGL125: 130nm, 125 kgates, 32kbits on-chip RAM, 1 kbits Flash, PLL for clock management.
- Supply voltages 0 to 1.65V
- Power consumption: 2.2uW, 16uW, 1 to 30mW in sleep, freeze, run modes
- e.g. Viterbi decoderViterbi decoderA Viterbi decoder uses the Viterbi algorithm for decoding a bitstream that has beenencoded using forward error correction based on a convolutional code....
for link layer implemented on the FPGA consumes 5mW
- Low-power Igloo FPGA from Actel
Networking
- MAC layer: preamble sampling protocol
PowWow uses RICER protocol proposed by UC Berkeley to reduce the time spent in radio reception (RX) mode. This protocol consists in cycled rendez-vous initiated by a wake-up beacon from potential receivers. Thanks to this method, nodes are sleeping most of the time, hence saving energy.
- Multi-hop routing
- Geographical routing
PowWow uses a simple geographical routing protocol.
-
- Each node has (x,y) coordinates
- Next node for hop transmission is chosen in the neighbors as the nearest to the destination
in the sense of Euclidian distance
- Neighbor table management
- A neighbor is a node in the radio range of a node
- Neighbors are discovered at power-up and on regular time period
- Transmission modes
- Broadcast
- Direct transmission to {neighbors}, no ACK
- Flooding
- Broadcast a packet to all network nodes, no ACK
- Direct Hop with/without ACK
- Direct transmission to a specific neighbors with/without ACK
- Robust Multi-Hop
- Multi-hop transmission to a specific node in the network
- Each hop is with ACK
- Uses node address
- Broadcast
Software
PowWow software distribution provides an API organized into protocol layers (PHY, MAC, LINK, NET and APP). The software is based on the protothread library of ContikiContiki
Contiki is a small, open source, highly portable multitasking computer operating system developed for use on a number of memory-constrained networked systems ranging from 8-bit computers to embedded systems on microcontrollers, including sensor network motes...
, which provides a sequential control flow without complex state machines or full multi-threading.
- Memory efficiency: 6 Kbytes (protocol layers) + 5 Kbytes (application)
- Over-the-air re-programmation (and soon reconfiguration)
Development Tools
- Currently based on IAR Embedded Workbench
- Compiling with gccGNU Compiler CollectionThe GNU Compiler Collection is a compiler system produced by the GNU Project supporting various programming languages. GCC is a key component of the GNU toolchain...
for MSP430 is also possible - Energy estimation methodology
Availability
The first version of PowWow were released July, 2009. PowWow V1 includes the motherboard, the radio board and the software. A first prototype of the coprocessing board is currently available but not yet distributed. PowWow V2 is under development.PowWow is delivered as an open source
Open source
The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
hardware and open source software under the GPL license.