System-on-Chip

CC2431 System-on-Chip for 2.4 GHz ZigBee™/ IEEE 802.15.4 with Location Engine Applications • • • • • • ZigBee™ systems 2.4 GHz IEEE 802.15.4 systems Home/building automation Industrial Control and Monitoring Low power wireless sensor networks Access Control • • • • • • PC peripherals Set-top boxes and remote controls Consumer Electronics Container/Vehicle Tracking Active RFID Inventory Control Product Description The CC2431 is a true System-On-Chip (SOC) for wireless sensor networking ZigBee™ / 802.15.4 solutions with location detection engine hardware onboard allowing location accuracy of around 3 meters or less. It enables ZigBee™ nodes to be built with very low total bill-of-material costs. The CC2431 combines the excellent performance of the leading CC2420 RF transceiver with an industry-standard enhanced 8051 MCU, 128 KB flash memory, 8 KB RAM and many other powerful features. Combined with the industry leading ZigBee™ protocol stack (Z-Stack™) from Figure 8 Wireless / Chipcon, the CC2431 provides the market’s most competitive ZigBee™ solution. The CC2431 is highly suited for systems where ultra low power consumption is required. This is achieved by various operating modes. Short transition times between these modes further ensure low power consumption. Key Features • • • • • • Location Engine accurately calculates the location of a node in a network High performance and low power 8051 microcontroller core. 2.4 GHz IEEE 802.15.4 compliant RF transceiver (industry leading CC2420 radio core). Excellent receiver sensitivity and robustness to interferers 128 KB in-system programmable flash 8 KB RAM, 4 KB with data retention in all power modes • • • • • Powerful DMA functionality Very few external components Only a single crystal needed for mesh network systems Low current consumption (RX: 27mA, TX: 25mA, microcontroller running at 32 MHz) Only 0.9µA current consumption in power-down mode, where external interrupts or the RTC can wake up the system This data sheet contains preliminary data, and supplementary data will be published at a later date. Chipcon reserves the right to make changes at any time without notice in order to improve design and supply the best possible product. The product at this point is not fully qualified. CC2431 PRELIMINARY Data Sheet (Rev. 1.01) SWRS034A Page 1 of 13 CC2431 Key Features (continued) • • Less than 0.6µA current consumption in power-down mode, where external interrupts can wake up the system Very fast transition times from lowpower modes to active mode enables ultra low average power consumption in low duty-cycle systems CSMA/CA hardware support Wide supply voltage range (2.0V – 3.6V) Digital RSSI/ LQI support Battery monitor and temperature sensor 8-14 bits ADC with up to eight inputs • • • • • • • • • • • • • 128-bit AES security coprocessor Two powerful USARTs with support for several serial protocols. Hardware debug support Watchdog timer One IEEE 802.15.4 MAC Timer, one general 16-bit timer and two 8-bit timers RoHS compliant 7x7mm QLP48 package 21 general I/O pins, two with 20mA sink/source capability Powerful and flexible development tools available Note: The CC2431 and the CC2430 are pin compatible, and the MCU and RF parts of the CC2430-F128 are identical to the CC2431 except the Location Engine. This data sheet complements the CC2430 data sheet with a description of the Location Engine. For complete information about the CC2431, please refer to the CC2430 data sheet in addition to this data sheet. CC2431 PRELIMINARY Datasheet (Rev. 1.01) SWRS034A Page 2 of 13 CC2431 Table Of Contents 1 2 2.1 2.2 3 4 4.1 4.2 4.3 4.4 4.5 REGISTER CONVENTIONS ................................................................................................................. 4 LOCATION ENGINE .............................................................................................................................. 5 LOCATION ENGINE OPERATION ................................................................................................................... 5 LOCATION ENGINE REGISTERS .................................................................................................................. 10 ORDERING INFORMATION .............................................................................................................. 12 GENERAL INFORMATION ................................................................................................................ 12 DOCUMENT HISTORY ................................................................................................................................. 12 PRODUCT STATUS DEFINITIONS ................................................................................................................. 12 DISCLAIMER .............................................................................................................................................. 13 TRADEMARKS ............................................................................................................................................ 13 LIFE SUPPORT POLICY ............................................................................................................................... 13 CC2431 PRELIMINARY Datasheet (Rev. 1.01) SWRS034A Page 3 of 13 CC2431 1 Register conventions Each RF register is described in a separate table. The table heading is given in the following format: REGISTER NAME (XDATA Address) In the register descriptions, each register bit is shown with a symbol indicating the access mode of the register bit. The register values are always given in binary notation unless prefixed by ‘0x’ which indicates hexadecimal notation. Symbol R/W R R0 R1 W W0 W1 H0 H1 Access Mode Read/write Read only Read as 0 Read as 1 Write only Write as 0 Write as 1 Hardware clear Hardware set Table 1: Register bit conventions CC2431 PRELIMINARY Datasheet (Rev. 1.01) SWRS034A Page 4 of 13 CC2431 2 Location Engine The Location Engine is used to estimate the position of nodes in an ad-hoc wireless network. Reference nodes exist with known coordinates, typically because they are part of an installed infrastructure. Other nodes are blind nodes, whose coordinates need to be estimated. These blind nodes are often mobile and attached to assets that need to be tracked. The Location Engine implements a distributed computation algorithm that uses received signal strength indicator (RSSI) values from known reference nodes, such as mobile neighbor nodes with the same Location Engine, or fixed infrastructure nodes. Performing location calculations at the node level reduces network traffic and communication delays otherwise present in a centralized computation approach. The Location Engine has the following main features: • Three to eight reference nodes can be used for the location estimation algorithm Location estimate with resolution of 0.5 meters Time to estimate node location less than 40 µs Location range 64 x 64 meters Location error can be less than 3 meters, depending on factors described below Runs location estimation with minimum CPU usage To achieve the best possible accuracy one should use antennas that have nearisotropic radiation characteristics. The location error depends on signal environment, deployment pattern of reference nodes and the density of reference nodes in a given area. In general, having more reference nodes available improves the accuracy of the location estimation. 2.1 Location Engine Operation This section describes the basic steps required to obtain location estimates from the Location Engine. The Location Engine requires a set of three to eight reference coordinates to be input together with a set of measured parameters. The output from the Location Engine consists of a pair of estimated location coordinates. Before any input data is written, the Location Engine must be enabled by writing a 1 to the enable bit, LOCENG.EN. When the Location Engine is not in use, writing a 0 to LOCENG.EN will reduce the power consumption of the CC2431 by gating off the Engine’s clock signal. Figure 1 shows the basic operation of the Location Engine. • • • • • CC2431 PRELIMINARY Datasheet (Rev. 1.01) SWRS034A Page 5 of 13 CC2431 LOCENG.EN=1 Load coordinate pairs? yes LOCENG.REFLD=1 no Load reference coordinate pairs no Loaded 8 coordinate pairs? yes LOCENG.REFLD=0 LOCENG.PARLD=1 Load measured parameter or zero for unused reference no Loaded 10 parameters? yes LOCENG.PARLD=0 LOCENG.RUN=1 Wait no LOCENG.DONE=1 ? yes Read LOCX, LOCY and LOCMIN LOCENG.EN=0 Figure 1: Location Engine Operation CC2431 PRELIMINARY Datasheet (Rev. 1.01) SWRS034A Page 6 of 13 CC2431 2.1.1 Reference Coordinates n can be adjusted to describe the propagation environment in which a network of devices will operate. 2.1.2.1 Parameter Definitions The measured parameters are described in this section together with how these should be estimated. 2.1.2.1.1 Parameter A The Location Engine requires a set of between three and eight reference coordinates [x0, y0, x1, y1, … x7, y7] to be input. The reference coordinates express each reference nodes position in meters, as unsigned values in the interval [0, 63.75] meters. The finest possible resolution is 0.25 meter. The format used is fixed-point data with the two LSBs representing the fractional part and the remaining six bits representing the integer part. Reference coordinates are loaded into the RF register REFCOORD. Before writing to REFCOORD, a 1 must be written to the register bit LOCENG.REFLD to indicate that a set of reference coordinates are being written. Once the coordinate load process commences (LOCENG.REFLD =1), eight coordinate pairs must always be written. However, it is possible for the Location Engine to use less than eight reference coordinates, by marking certain reference coo