Integration Guide
SMK900 Integration Guide Revision 4
Broadcast Frame
In order to ensure synchronization of every nodes within a given network, the gateway always initiates
a broadcast beacon periodically, which encompasses a broadcast parameters. This is the primary
construct within which all nodes communicate. In particular, there is Time-Division Multiple Access
(TDMA) slotting mechanism that specify unique slots, called broadcast phases, for outbound
communication from a gateway to nodes, and inbound communication from a node back to a gateway.
Dynamic parameters
There is 6 parameters inside the broadcast beacon. They will be referred to in this integration guide
by the moniker: dynamic parameters, or, in short, DYN. Configuration of those parameters usually
take the form of a sequence of 6 bytes, with 1 byte per parameter, as follows:
DYN <= {B
O
, B
I
, N
H
, N
R
, R, D}
For each broadcast frame, the periodic delay between broadcast as well as its length being
determined by:
B
O
: number of gateway to node messages per broadcast (also called broadcast out phase count),
B
I
: number of node to gateway messages (also called broadcast in phase count),
N
H
: the maximum number of hops for the network
(i.e. maximum number of time a message can be relayed from node to node),
N
R
: number of random-access specialized hop slots (called redux),
R: specialized slotting mechanism enabled
D: inverted sleep-wake duty cycle ratio D (min. value is 1),
The broadcast time can be then calculated as:
T
BCAST
[msec] = 10 * ( N
H
*(B
O
+ B
I
) + N
R
*R )
The interval between each broadcast is:
T
INTERVAL
[msec] = T
BCAST
* D
For the vast majority of applications, the default settings, where B
O
= B
I
= 1 and R = 0, are applicable,
in which case the timing equations simplify to:
T
BCAST
[msec] = 20 * N
H
T
INTERVAL
[msec] = T
BCAST
* D
Allowable values for each of those are, with default values in (boldface):
B
O
: [(1), 2, 3, 4]
B
I
: [(1), 2, 3, 4]
N
H
: [1, 2, ... ,4, (5), 6, ... , 31]
N
R
: [(1)]
R: [(0), 1]
D: [1, 2, 5, (10), 20, 40, 80]
Note that D is defined as T
INTERVAL
/ T
BCAST
, and is thus the inverse of what is commonly defined as
the network duty-cycle, which is defined as follows:
duty cycle[%] = 100% / D
Note that there are no parameters controlling any acknowledgement/retry cycles in case a message
from one node to another fails to pass through. It is assumed that the onus of managing packet
delivery failure occurrences fall upon the shoulder of the higher-level protocol as implemented by
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