CWH1000 wireless communications overview
All wireless communication is handled by two 802.15.4 2.4GHz Radio Transceiver Modules controlled by a
STM32F205RBT7 microcontroller. There are a total of 15 Radio Channels split into 7 channel groups with
each channel group containing two channels. In addition, there is a configuration channel for when the
CWH1000 is put into network configuration mode. In network configuration mode, the first Radio Module
scans for free sensors to add to the group, while the second sensor looks at the energy in every channel
group to determine which groups are busy or noisy.
In run mode, the first radio module emits radio beacons on the first channel in the channel group while
the second radio module emits the same radio beacon but on the second channel in the channel group.
In the event that one of the channels becomes inoperable and the sensor loses communication with the
CWH1000, the sensor will seamlessly switch to the other channel in the channel group to re-establish
communication. This process repeats until the sensor re-establishes communication with the CWH1000.
CWH1000 RF communications initialization
During power up, the CWH1000 checks a switchable internal parameter to see if it should operate in
configuration mode or run mode.
If the CWH1000 is set to configuration mode, it will initialize to the configuration channel and listen for
any free sensors not already in a channel group.
If the CWH1000 is set to run mode, it will begin broadcasting immediately.
CWH1000 setting for the SA
The CWH1000 has one configuration input to set the Source Address (SA) which is capable of detecting
up to 3 distinct source addresses. The input can be connected directly to ground SA=235, left floating
(SA=last programmed value) or connected to ground through 2 different resistor values (see table
below). The default factory SA is 235. SA can also be configured via CAN using the PLUS+1® Service Tool.
The SA input is only checked during start-up. To change the SA values, the device must be powered up
with the SA input in the desired state. Any changes made to the SA input while the device is powered are
ignored.
If, on power up, the SA selected by the input state differs from the SA currently stored in non-volatile (NV)
memory, the new SA is written to NV memory, overwriting the current value.
Source Address and resistor values:
Source Address
Resistor (Ohms)
235 (0xEB)
0
236 (0xEC)
76.8
237 (0xED)
162
CWH1000 network parameters
The CWH1000 has several parameters stored in non-volatile memory that are used for configuration of
the wireless hub. These parameters can be modified using the PLUS+1® Service Tool or, in some cases, by
a CAN message. They include the following:
CAN communications:
PLUS+1 Service Tool signal (sensor
parameter)
Allowable values
Comments
CANBaudRate:
100,000; 125,000; 250,000; 500,000; 1,000,000
Default=250,000
CANUpdateRate:
5-250mS
Default=10mS
UseExtendedID:
0 = 11 bit, 1 = 29 bit
Default=1(29 bit)
ID:
0- 536870911(0x00-0x1FFFFFFF)
Default=0x18FFB2
Technical Information
CWH1000 Wireless Hub
CWH1000 wireless communications
12
L1321661 • Rev AA • Mar 2014
