The oscilloscope screen capture shows a single byte being transmitted by TXL2. A BiM2-433-64
transceiver is used to capture the transmitted data The character appears on the serial data output
(RXD) pin of the RXL2 after about 12.5ms. Busy (STATUS) pin is momentarily set high to indicate the
presence of a valid data in the receive buffer of the RXL2.
It can be clearly seen that unlike raw radio modules, RXL2 does not output any noise when there is not
any transmission. Data fed into the TXD input of a TXL2 transmitter appears at the RXD output of a
RXL2 receiver within radio range in the original form it was fed.
Figure 7: 16kbps Bi-phase encoded continuous data stream (expanded view)
Continuous serial data at 9600bps (above) is encoded as half-cycles of 8kHz (62.5µs long bit) and 16kHz
(31.25µs short bit).
Programming the TXL2/RXL2
In order to use all the functions embedded in the TXL2/RXL2, the user must be aware of the
setup/programming facility, which allow different addresses and frequency channels to be set up, and if
necessary accesses diagnostic test modes.
Both modules are is programmed through the same RS232 port that is used for sending/receiving data.
An RS232 terminal emulator (such as Aterm or HyperTerminal) is an ideal tool.
TXL2 and RXL2 can be put to program mode by pulling the TEST and PGM pins respectively.
The unit will only respond to certain command strings:
ADDR0 to ADDR7 <CR>:
CHAN0 to CHAN4 <CR>:
These commands set up one of 8 unique addresses.
These commands select one of 5 preset channels
A TXL2 will only communicate with an RXL2 unit set to the same address and the same channel.
Address and channel numbers are stored in volatile memory. On power-up both will revert to the
default in EEPROM (as supplied this is always address 0 and Channel 0)
SETPROGRAM <CR>:
Writes the current address and current channel into EEPROM as the
new default.
A tilda character (~, ascii 126dec) sent by the unit indicates end of
EEPROM write sequence
Radiometrix Ltd
TXL2/RXL2 Data Sheet
page 8
RADIOMETRIX [ RADIOMETRIX LTD ]
