9XTend
‐
PKG
‐
E™
Ethernet
RF
Modem
–
Product
Manual
v2.x4x
[2007.01.04]
©
2007
MaxStream,
Inc.,
Confidential
&
Proprietary
‐
All
Rights
Reserved
13
3.
RF
Modem
Operation
WARNING: When operating at 1 Watt power output, observe a minimum separation distance of 2' (0.6m) between
modems. Transmitting in close proximity of other modems can damage modem front ends.
3 .1 . Se r ia l Com m u n ica t ion s
3 .1 .1 . Tr a n spa r e n t Ope r a t ion
By default , XTend RF Modem s operat e in Transparent Mode. The m odem s act as a serial line
replacem ent - all UART dat a received t hr ough t he DI pin is queued up for RF t ransm ission. When
RF dat a is received, t he dat a is sent out t he DO pin.
When t he RO ( Packet izat ion Tim eout ) param et er t hr eshold is sat isfied, t he m odem at t em pt s t o ini-
t ialize an RF t ransm ission. I f t he m odem cannot im m ediat ely t ransm it ( for inst ance, if it is already
receiving RF dat a) , t he serial dat a cont inues t o be st ored in t he DI Buffer. Dat a is packet ized and
sent at any RO t im eout or w hen t he m axim um packet size is r eceived.
The m odem operat es as described above unless t he Com m and Mode Sequence is det ect ed. The
Com m and Mode Sequence consist s of t hree copies of t he com m and sequence charact er [ CC
param et er] surrounded by t he before and aft er guard t im es [ BT & AT param et ers] .
I f t he DI buffer becom es full, hardware or soft ware flow cont rol m ust be im plem ent ed in order t o
prevent overflow ( loss of dat a bet w een t he host and m odem ) .
3 .1 .2 . API Ope r a t ion
API ( Applicat ion Program m ing I nt erface) Operat ion is an alt ernat ive t o t he default Transparent
Operat ion. The API is fram e- based and ext ends t he level t o w hich a host applicat ion can int eract
w it h t he net w orking capabilit ies of t he m odule. When in API m ode, all dat a ent er ing and leaving
t he RF m odem is cont ained in fram es t hat define operat ions or event s w it hin t he m odem .
Transm it Dat a Fram es ( received t hr ough t he DI ( Dat a I n) pin) include:
• 16- bit address
Receive Dat a Fram es ( sent out t he DO ( Dat a Out ) pin) include:
• Show ing a received RF packet ( 16 bit s only)
• Response t o a TX ( Transm it ) packet
• Show ing event s such as hardware reset , wat chdog reset , asynchronous event s, et c.
The m odem will send dat a fram es t o t he applicat ion cont aining st at us packet s; as w ell as source,
RSSI and payload inform at ion from r eceived dat a packet s.
API operat ion opt ion facilit at es m any operat ions such as t he exam ples cit ed below :
To implement API operations, refer to ‘API Operation’ sections [p42].
- >
Change dest inat ion addresses wit hout having t o ent er com m and m ode
- >
Receive success/ failure st at us of each RF packet
- >
I dent ify t he source address of each received packet
