CC2431 Datasheet, PDF (10/16 Pages) Texas Instruments – System-on-Chip for 2.4 GHz ZigBee-TM / IEEE 802.15.4 with Location Engine

(LOCENG.PARLD =1), all 22 parameters must
be written.
The measured parameters must be written in
the order [A, n, x_min, x_delta, y_min, y_delta, rssi₀, rssi₁,
…, rssi₁₅] to the MEASPARM register. Once
the parameter load process commences
2.1.3 Location Estimation
The estimated location coordinates are given
in meters in the interval [0.0, 63.75] with
resolution 0.25 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. The time until estimated coordinates can be
read varies with the search boundary
parameters, from 50 µs to 13 ms (with 32
MHz system clock) after LOCENG.RUN was
set to 1. The Location Engine does not
produce any interrupt requests.
The value of the X coordinate estimate given
by LOCX includes an offset value which must
be removed to obtain the actual X coordinate.
The offset removal must be performed after
2.2 Location Engine Register
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 X
coordinate
• LOCY
- Location estimate Y
coordinate
CC2431
(LOCENG.PARLD =1) it must be completed
with all 22 parameters. Included in these are
the 16 RSSI values which must be all written,
so any unused slots must be written as zeros.
After all 22 parameters have been written, a 0
must be written to the register bit
LOCENG.PARLD.
reading the LOCX register, to obtain the actual
X value as follows:
X = (X_LOCX - x_min +1) % ( x_delta+ 1) + x_min
Where X_LOCX is the value read from register
LOCX, and x_min and x_delta are the boundary
parameters used as inputs to limit the search
as described in section 2.1.2.1.4. Notice that
the Y coordinate read LOCY from can be used
directly.
The estimated coordinates remain valid in the
LOCX and LOCY registers until new results
have been calculated or until a reset.
Note that LOCENG.EN must be 1 during
operation of the Location Engine.
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.
CC2431 Data Sheet (Rev. 2.01) SWRS034B
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