FM N
ARROW
B
AND
T
RANSCEIVERS
TRXQ1
RXQ1
If operation in the broadcast mode is required then with a new device, no action is necessary. If a device has
been used in the point to point addressed mode or if its status is unknown then status erase must be carried
out using the following procedure.
The LEARN pin is grounded for a period of 5 seconds and is then allowed to float, please note the unit must
be in addressed mode in order to do this. The status LED then flashes slowly for 3 seconds to indicate that
the device is erased and will now only operate in the broadcast mode until the learn sequence is repeated.
If operation in the addressed mode is required then the following procedure has to be followed to allow the two
nodes in the system to operate together.
The option for addressed mode is selected.
The two nodes, ‘A’ and ‘B’ are placed within radio range of one another are powered up.
The LEARN pin on one device – say ‘B’ is briefly taken low, placing the node into learn mode.
The LEARN/ERASE status LED on ‘B’ comes on and remains on for 20 seconds. If within this
period, no ‘learn’ data packet is received (see below) then the LED will be extinguished and the
device will operate normally.
At node ‘A’, the LEARN pin is briefly taken low. The LEARN/ERASE status LED will then come
on and node ‘A’ will transmit its address.
Node ‘B’ will receive and store the address of ’A’.
Node ‘B’ sends back to node ‘A’ both its address and that of node ‘A’.
Node ‘A’ receives and stores the address of ’B’ and confirms to ‘B’ that it has received the its
address.
Both node ‘A’ and ‘B’ LED's flash their its status LED’s rapidly for 3 seconds to show that they
have learned each others addresses.
Addressed mode can then be entered by setting the mode selection pin on the chip as
described in the PIN Descriptions table on page 5.
(other nodes which may be active will ignore this transfer since they have not been placed in the learn mode)
LRN/LED pin (addressed mode only)
The learn/LED pin is used both to sense the learn/erase switch and also to drive the indicator LED and should
be connected as shown in the RXQ1 application circuit. The switch, which should be of the normally open
type, should be connected from the learn pin to ground. The LED and its series current limiting resistor should
be connected from Vcc to the learn pin, ensuring that the maximum current drawn by the LED (as given in this
data sheet) is not exceeded.
TRXQ1 Loop Mode
Loop mode is provided to allow testing of the performance of a system and allows node ‘A’ to transmit a data
packet which will be looped back by node ‘B’ and received by node ‘A’. The mode settings of the nodes are
ignored in the loop mode and the transfer is carried out in broadcast mode. The mode must only be selected
when there are just two nodes in a network.
If we assume that we wish to send a host data packet from node ‘A’ to node ‘B’ and have the packet returned
such that host ‘A’ receives back its data packet then the LOOP link in node ‘A’ should be made before that unit
is powered up. This unit will now only operate in the loop mode until it is powered down, the loop link removed
and then powered up again.
DS0353-9 March ‘05
©2005 Reg. No. 227 4001, ENGLAND
Page 8
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