TI CC2431 System-on-chip for 2.4 ghz zigbee-tm / ieee 802.15.4 with location engine Datasheet

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
•
•
•
•
•
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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 powerdown mode, where external interrupts or
the RTC can wake up the system
Less than 0.6µA current consumption in
stand-by mode, where external interrupts
can wake up the system
Very fast transition times from low-power
modes to active mode enables ultra low
average power consumption in low dutycycle systems
CSMA/CA hardware support
Wide supply voltage range (2.0V – 3.6V)
Digital RSSI / LQI support
Battery monitor and temperature sensor
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CC2431
Key Features (continued)
•
•
•
•
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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.
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CC2431
Table Of Contents
1
REGISTER CONVENTIONS ................................................................................................................. 4
2
2.1
2.2
3
LOCATION ENGINE .............................................................................................................................. 5
LOCATION ENGINE OPERATION ................................................................................................................... 5
LOCATION ENGINE REGISTERS .................................................................................................................. 10
ORDERING INFORMATION .............................................................................................................. 12
4
4.1
4.2
4.3
4.4
4.5
5
GENERAL INFORMATION ................................................................................................................ 12
DOCUMENT HISTORY ................................................................................................................................. 12
PRODUCT STATUS DEFINITIONS ................................................................................................................. 12
DISCLAIMER .............................................................................................................................................. 13
TRADEMARKS ............................................................................................................................................ 13
LIFE SUPPORT POLICY ............................................................................................................................... 13
ADDRESS INFORMATION ................................................................................................................. 14
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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
Access Mode
R/W
Read/write
R
Read only
R0
Read as 0
R1
Read as 1
W
Write only
W0
Write as 0
W1
Write as 1
H0
Hardware clear
H1
Hardware set
Table 1: Register bit conventions
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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.
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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
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CC2431
2.1.1
Reference Coordinates
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 coordinates as unused. Zeros
can be used to fill the unused reference
coordinate slots, and they will be
interpreted as unused when 0.0 is loaded
as the RSSI value for those reference
coordinates.
The reference coordinates are written in
the order [x0, y0, x1, y1, …, x7, y7] to the
register REFCOORD. After all coordinates
have been written, a 0 is written to the
register bit LOCENG.REFLD.
2.1.2 Measured Parameters
After the reference coordinates have been
written, a set of measured parameters
must be input to the Location Engine.
These parameters consist of two radio
parameters and eight RSSI values. The
radio parameters are the values A and n.
These radio parameters are used in the
Engine’s algorithm used to find the
estimated location. The parameters A and
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 radio parameter A is defined as the
absolute value of the average power in
dBm received at a close-in reference
distance of one meter from the transmitter,
assuming an omni-directional radiation
pattern.
For example, if the mean
received power at one meter is -40 dBm,
the parameter A is specified as 40.
The Engine expects the parameter A to be
in the range [30.0, 50.0] with precision 0.5.
The parameter A is given as an unsigned
fixed-point value where the LSB bit is the
fractional bit and the remaining bits are the
integer part. A typical value for A is 40.0.
2.1.2.1.2 Parameter n
The radio parameter n is defined as the
path loss exponent that describes the rate
at which the signal power decays with
increasing distance from the transmitter.
This decay is proportional to d-n where d is
the distance between transmitter and
receiver.
The actual parameter n value written to
the Location Engine is an integer index
value selected from a lookup table shown
in Table 2.
As an example, in the case when the
value n=2.98 is found from measurements,
the closest available value of n in the
lookup table is 3.00, corresponding to
index 13. Therefore, the integer value 13
is used for the parameter n written to the
Location Engine.
Refer to section 2.1.2.1.3 in order to find
the
value
for
n
to
be
used.
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CC2431
n index
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
n
1.000
1.250
1.500
1.750
1.875
2.000
2.125
2.250
2.375
2.500
2.625
2.750
2.875
3.000
3.125
3.250
n index
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
n
3.375
3.500
3.625
3.750
3.875
4.000
4.125
4.250
4.375
4.500
4.625
5.000
5.500
6.000
7.000
8.000
Table 2: n parameter lookup table
The parameter n is written to the Location
Engine as an integer index in the range [0,
31] as the index is given as an integer
value with no fractional bits, e.g. the value
n = 7 is loaded as 00000111. A typical
value for n is 13.
2.1.2.1.3 Parameter Estimation
The parameters A and n can be estimated
empirically by collecting RSSI data (and
therefore path loss data) for which the
distances between the transmitting and
receiving devices are known. Figure 2 is a
scatter plot of abs(RSSI) data versus log
distance in meters. A least-squares best-fit
line is used to glean the specific values of
A and n for the environment in which the
data were measured:
•
A is the y-intercept of the line, and
•
n is the slope of the line
The data in Figure 2 give A=42.4 and
n=2.98 for that environment. Note that the
plot in this example does not show the
actual y-intercept i.e. the point on the line
where x=0.
The value of A loaded into the engine in
this case would by 42.5. The value of n
loaded into the engine, is seen to be 13
from Table 2.
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CC2431
Path Loss vs. log-distance for source 0x85, Z=2.1082. A=42.4103, n=2.9773
95
90
85
Path Loss (dB)
80
75
70
65
60
55
50
45
2
4
6
8
10*log10(distance)
10
12
14
Figure 2: Path loss vs. log distance
2.1.2.1.4 RSSI Values
The RSSI values are the RSSI
measurements corresponding to the set of
reference coordinates. The RSSI values
are within the interval [-40 dBm, -95 dBm]
with precision 0.5 dBm. The negative sign
is removed in the value written. As an
example, in the case where the value
RSSI = -50.35 dB, this would be written
into the location engine as 50.5.
Note that a value of 0.0 must be written as
RSSI value for unused reference
coordinates. The engine will not function
correctly if only some of the parameters
are loaded.
2.1.2.2 Loading Parameters
All measured parameters are loaded into
the RF register MEASPARM. Before writing
to MEASPARM, a 1 must be written to the
register bit LOCENG.PARLD to indicate
that a set of measured parameters are
being written. Once the parameter load
process commences (LOCENG.PARLD
=1), all ten parameters must be written.
The measured parameters must be written
in the order [A, n, rssi0, rssi1, … rssi7] to
Once the
the MEASPARM register.
parameter load process commences
(LOCENG.PARLD =1) it must be
completed. Eight RSSI values must be
written, so any unused slots must be
written as zeros. After all ten parameters
have been written, a 0 must be written to
the register bit LOCENG.PARLD.
2.1.3 Location Estimation
The estimated location coordinates are
given in meters in the interval [0.0, 63.5]
with precision 0.5 m. The data format uses
the LSB bit as the fractional part.
When
reference
coordinates
and
measured parameters have been loaded,
the location estimate is calculated by
writing 1 to the LOCENG.RUN register bit.
The estimated coordinates can be read
from the LOCX and LOCY registers when
LOCENG.DONE is set to 1. This occurs
1200 system clock cycles (16/32 MHz)
after LOCENG.RUN was set to 1. The
Location Engine does not produce any
interrupt requests.
The estimated coordinates remain valid in
the LOCX and LOCY registers until new
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CC2431
results have been calculated or until a
reset.
•
Note that LOCENG.EN must be 1 during
operation of the Location Engine.
•
2.2 Location Engine Registers
This section describes the RF registers
associated with the Location Engine.
These registers are:
•
LOCENG
Location Engine
control and status
•
REFCOORD
Reference
coordinates input
•
MEASPARM
Measured
parameters input
LOCX
Location estimate
LOCY
Location estimate
LOCMIN
Minimum function
X coordinate
Y coordinate
•
estimate
The RF registers reside in XDATA memory
space. Table 3 gives an overview of
register addresses while the remaining
tables in this section describe each
register in detail. Refer also to section 1
for Register conventions.
For the remaining RF registers refer to the
CC2430 Data Sheet.
Table 3 : Overview of Location Engine RF registers
XDATA
Address
Register name
Description
0xDF55
REFCOORD
Reference coordinates input
0xDF56
MEASPARM
Measured parameters input
0xDF57
LOCENG
Location Engine control and status
0xDF58
LOCX
Location estimate X coordinate
0xDF59
LOCY
Location estimate Y coordinate
0xDF5A
LOCMIN
Minimum function estimate
0xDF60
CHVER
Chip Version
0xDF61
CHIPID
Chip Identification
Bit
Name
Reset
R/W
Description
7:0
REFCOORD
0
R/W
Location Engine reference coordinate [x0, y0, x1, y1, … x7,
y7]
Table 4: Register REFCOORD (0xDF55)
Bit
Name
Reset
R/W
Description
7:0
MEASPARM
0
R/W
Location Engine measured parameters of channel and
reference nodes [A, n, rssi0, rssi1, …, rssi7]
Table 5: Register MEASPARM (0xDF56)
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CC2431
Bit
Name
Reset
R/W
Description
7:5
-
00
R0
Reserved, read as 0.
4
EN
0
R/W
Enable location engine
0
Disable location engine
1
Enable location engine
3
DONE
0
R
Estimation completed. After 1 has been written to RUN, this
bit is cleared and then set to 1 when the estimated data is
ready.
2
PARLD
0
R/W
Load parameters. This bit shall be written as 1 before the
set of parameters are written to MEASPARM. Write 0 to this
bit after the last parameter has been written.
1
REFLD
0
R/W
Load reference coordinates. This bit shall be written as 1
before the set of coordinates are written to REFCOORD.
Write 0 to this bit after the last coordinate has been written.
0
RUN
0
R0W1
Location estimate start. This bit shall be written as 1 when
desired coordinates and parameters have been written to
REFCOORD and MEASPARM registers. Estimation
process starts when 1 is written to this bit. Always read as
0.
Table 6: Register LOCENG (0xDF57)
Bit
Name
Reset
R/W
Description
7:0
LOCX
00h
R
Location estimate X coordinate.
Table 7: Register LOCX (0xDF58)
Bit
Name
Reset
R/W
Description
7:0
LOCY
00h
R
Location estimate Y coordinate.
Table 8: Register LOCY (0xDF59)
Bit
Name
Reset
R/W
Description
7:0
LOCMIN
00h
R
Location estimate minimum value
Table 9: Register LOCMIN (0xDF5A)
Bit
Name
Reset
R/W
Description
7:0
VERSION[7:0]
0x01
R
Chip revision number
Table 10: Register CHVER (0xDF60)
Bit
Name
Reset
R/W
Description
7:0
CHIPID[7:0]
0x89
R
Chip identification number. Always read as 0x89.
Table 11: Register CHIPID (0xDF61)
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CC2431
3
Ordering Information
Ordering part number
Description
Minimum Order
Quantity (MOQ)
1371
CC2431-RTB1
CC2431, QLP48 package, RoHS compliant Pb-free assembly in
tubes with 43 pcs per tube, Single Chip RF Transceiver
43
1372
CC2431-RTR1
CC2431, QLP48 package, RoHS compliant Pb-free assembly,
tape and reel with 2500 pcs per reel, Single Chip RF Transceiver
2500
1367
CC2431DK
CC2431 ZigBee Development Kit
1
1368
CC2431ZDK Pro
CC2431 ZigBee Development Kit including support and training
1
Table 12: Ordering Information
4
General Information
4.1
Document History
Revision
Date
Description/Changes
1.0
2005-11-30
First release
Table 13: Document History
4.2
Product Status Definitions
Data Sheet Identification
Product Status
Definition
Advance Information
Planned or Under
Development
This data sheet contains the design specifications for product
development. Specifications may change in any manner without
notice.
Preliminary
Engineering Samples
and First Production
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.
No Identification Noted
Full Production
This data sheet contains the final specifications. Chipcon
reserves the right to make changes at any time without notice in
order to improve design and supply the best possible product.
Obsolete
Not In Production
This data sheet contains specifications on a product that has
been discontinued by Chipcon. The data sheet is printed for
reference information only.
Table 14: Product Status Definitions
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CC2431
4.3
Disclaimer
Chipcon AS believes the information contained herein is correct and accurate at the time of this printing. However,
Chipcon AS reserves the right to make changes to this product without notice. Chipcon AS does not assume any
responsibility for the use of the described product; neither does it convey any license under its patent rights, or the rights
of others. The latest updates are available at the Chipcon website or by contacting Chipcon directly.
As far as possible, major changes of product specifications and functionality, will be stated in product specific Errata Notes
published at the Chipcon website. Customers are encouraged to sign up for the Chipcon Newsletter for the most recent
updates on products and support tools.
When a product is discontinued this will be done according to Chipcon’s procedure for obsolete products as described in
Chipcon’s Quality Manual. This includes informing about last-time-buy options. The Quality Manual can be downloaded
from Chipcon’s website.
Compliance with regulations is dependent on complete system performance. It is the customer’s responsibility to ensure
that the system complies with regulations.
The ZigBee Specification includes intellectual property rights of ZigBee Alliance member/promoter companies. Chipcon is
a ZigBee Alliance Promoter. Under the ZigBee Alliance terms of use, no part of the Specification may be used by a
company in the development of a product for sale without such company becoming a member of the ZigBee Alliance.
Therefore, the Figure 8 Wireless Z-Stack™ may only be used for commercial purposes by ZigBee Alliance member
companies. If a customer desires to use the Figure 8 Wireless Z-Stack™ or any other third party ZigBee stack together
with a product described in this datasheet, the customer is responsible for complying with the applicable ZigBee Alliance
policies. See http://www.zigbee.org.
This Chipcon product contains Flash memory code protection. However, Chipcon does not guarantee the security of this
protection. Chipcon customers using or selling these products with program code do so at their own risk and agree to fully
indemnify Chipcon AS for any damages resulting from the use or sale of such products.
Chipcon believes that the Flash memory protection used in this product is one of the most secure in the market today
when used in the intended manner and under normal conditions. However, there might be methods to breach the code
protection feature. Neither Chipcon nor any other semiconductor manufacturer can guarantee the security of their code
protection. Code protection does not mean that we are guaranteeing the product as “unbreakable”.
This Chipcon product contains hardware AES encryption. Chipcon does not guarantee the security of the key protection or
the security of the encryption scheme. Chipcon customers using or selling products with AES do so at their own risk and
agree to fully indemnify Chipcon AS for any damages resulting from the use or sale of such products.
It is the Chipcon customer's responsibility to ensure that sale or export/import of products including this Chipcon product
with AES encryption is sold with the required export/import licenses, if necessary, and does not violate any applicable
export/import and/or other trade restrictions.
4.4
Trademarks
SmartRF® is a registered trademark of Chipcon AS. SmartRF® is Chipcon's RF technology platform with RF library cells,
modules and design expertise. Based on SmartRF® technology Chipcon develops standard component RF circuits as well
as full custom ASICs based on customer requirements and this technology.
All other trademarks, registered trademarks and product names are the sole property of their respective owners.
4.5
Life Support Policy
This Chipcon product is not designed for use in life support appliances, devices, or other systems where malfunction can
reasonably be expected to result in significant personal injury to the user, or as a critical component in any life support
device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or
system, or to affect its safety or effectiveness. Chipcon AS customers using or selling these products for use in such
applications do so at their own risk and agree to fully indemnify Chipcon AS for any damages resulting from any improper
use or sale.
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