Application Note
AN042
3.1 Node types
3.1.1 Reference node
A node which has a static location is called a reference node. This node must be configured
with X and Y value that correspond to the physical location.
The main task for a reference node is to provide a “reference” packet that contains X and Y
coordinates to the blind node, also referred to as an anchor node.
Since this node is not using the hardware location engine at all, it is not necessary to use a
CC2431 for the purpose. This means that a reference node can be run on either a CC2430 or
a CC2431. Since CC2430/31 is based on the same transceiver as CC2420, even a CC2420
together with a suitable microcontroller can be used as reference node.
3.1.2 Blind Node
A blind node will communicate with the closest reference nodes, collecting X, Y and RSSI for
each of these nodes, and calculate its position based on the parameter input using the
location engine hardware. Afterwards the calculated position should be sent to a control
station. This control station could be a PC or another node in the system.
A blind node must be using CC2431.
3.2 The location hardware
The location engine utilizes an extremely simple interface seen from the software layer; write
parameters in, wait for the calculation to performed, and read out the calculated position out.
This chapter will discuss the different parameters and how the shall be interpreted.
Figure 2: Location Engine, input and output
Application Note AN042 (Rev. 1.0)
SWRA095
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