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FMRXQ1-433

P1-P3P4-P6P7-P9P10-P12
DS0353-9 March ‘05 ©2005 Reg. No. 227 4001, ENGLAND Page 7
TRXQ1
RXQ1
FM N
ARROW BAND TRANSCEIVERS
TRXQ1 Operating Modes
The device is capable of operation in one of two modes, either broadcast or addressed. The following
description describes the features of these mode and assumes two TRXQ1 nodes ‘A’ and ‘B’. The RF600T
must be configured before power up for either the broadcast or addressed mode of operation by means of the
MODE pin. Note that for security, broadcast nodes will not receive data from addressed nodes
Broadcast mode.
This mode allows a host generated data block from node ‘A’ to be transmitted and received by any number of
other nodes. This data is received and verified (for correct Manchester coding and CRC) by the other nodes
before being output to their host devices. Alternately, in the same way the other nodes can send data to node
‘A’. Note that although any node can initiate a transfer, only one direction of transfer can be active at a given
time. Correct reception of a data packet is not acknowledged and the node hosts have the responsibility of
ensuring that data transfers occur as required by operating some form of message protocol over the half
duplex data link.
Addressed mode
This mode allows a host generated data block from node ‘A’ to be transmitted and for the data frame to be
addressed to one other network node – in this case we assume node ‘B’. When the data is received by node
‘B’ it is verified for correct Manchester coding, CRC and for address match and then an acknowledge
message is transmitted back to node ‘A’. Node ‘A’ then outputs a confirmation to the host in the form of the
ASCII character ‘C’ (Confirmed). Note that confirmation is given when the data block is stored in the buffer of
node ‘B’ and not when it has been delivered to the host at node ‘B’.
All message transfers are tagged with the addresses of both the origin and destination, thus ensuring secure
data transfer at all times. Either node ‘A’ or node ‘B’ can initiate a transfer but only one direction of transfer
can be active at a given time. In the event that the originating node does not get confirmation of receipt of the
data packet, the software re-tries the transfer five times after which node ‘A’ will output an error message to
the host in the form of the ASCII character ‘F’ (Failed).
Correct reception (or otherwise) of a data packet is thus acknowledged and the host devices are relieved of
most of the workload of ensuring that data transfers occur as required.
The RF600T must be configured before use for either the broadcast or addressed point to point mode of
operation and details of how this is carried out are given in the following section.
System Operation
Each RF600T is programmed at manufacture with a 24 bit serial number which uniquely identifies the device.
In an addressed point to point system, these serial numbers are used as the device address for the nodes in
the system and non-volatile eeprom memory in the device stores the address of the ‘other’ node in the system.
If, as at time of manufacture, no address has been stored in the device or if the address has been erased then
the device will only operate in the broadcast mode. If however an address has been stored then the device will
also be able to operate in the addressed point to point mode.
DS0353-9 March ‘05 ©2005 Reg. No. 227 4001, ENGLAND Page 8
TRXQ1
RXQ1
FM N
ARROW BAND TRANSCEIVERS
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 9
TRXQ1
RXQ1
FM N
ARROW BAND TRANSCEIVERS
TRXQ1 application schematic: RS232 connection to host PC.
Connection of the TRXQ1 to an RS232 host terminal device such as a PC serial port can be simply carried out
using the circuit shown below. The 9 way ‘D’ socket (CON1) provides the standard pinout required to connect
directly to the serial port of any PC using a 9 way male/female cable. The MAX222 provides level conversion
between the RS232 levels on the serial port and the logic levels pins of the TRXQ1 module. (note that direct
connection of RS232 levels to the module will result in immediate destruction of the device)
The TRXQ1 hybrid requires the following 4 signal connections to operate correctly:
Tx Data: this is serial data which is to be transmitted by the hybrid.
Rx Data: this is serial data which has been received by the hybrid.
\CTS: this control output to the host is low when it is Clear To Send data to the hybrid.
\RTS: this control input from the host is low when it is making a Request To Send data from the hybrid.
In this circuit, option selection is as follows:
RF Baud rate (pin 16): this pin is pulled high via a 22K resistor which selects 9600 bauds.
Host Baud Rate (pin 15): this pin is pulled high via a 22K resistor which 400 us element time.
Mode (pin 12): this pin is pulled high via a 22K resistor which addressed mode.
If two such circuits are constructed then it will be possible to interconnect two PC’s and test out the
performance of the hybrids. When both circuits are powered up is will be necessary for them to learn one
another’s identity as described fully in the RF600T data sheet (DS601). That is – press the learn switch in one
circuit, then in the other and the two learn LED's should flash showing that the learn has taken place.
The addressed mode operates as a point to point half duplex system with automatic retry and indication to the
transmitting host of the status of the transfer. Again the RF600T data sheet gives full information on this mode
of operation.
NOTE: pins 16, 15, 12 should not be left floating as these control important features of the TRXQ1 such as the
baud rate and Mode of operation. Ensure that these pins are pulled either high with a ~22K resistor or pulled
low with a ~2K2 resistor.
P1-P3P4-P6P7-P9P10-P12

FMRXQ1-433

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RF TXRX MODULE ISM<1GHZ
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