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TRXQ1 application schematic: RS232 connection to host PC.
TRXQ1
RXQ1
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:
Rx Data:
\CTS:
\RTS:
this is serial data which is to be transmitted by the hybrid.
this is serial data which has been received by the hybrid.
this control output to the host is low when it is Clear To Send data to the hybrid.
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):
Host Baud Rate (pin 15):
Mode (pin 12):
this pin is pulled high via a 22K resistor which selects 9600 bauds.
this pin is pulled high via a 22K resistor which 400 us element time.
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.
DS0353-9 March ‘05
©2005 Reg. No. 227 4001, ENGLAND
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