CXT2 Datasheet, PDF (7/12 Pages) Radiometrix Ltd – Multi channel 25kHz NBFM remote control TX/RX

Programming the CXT and CXR
A 2400 baud cmos level ‘inverted RS232 format’ (1 start bit, 8 data, 1or 2 stop bits, no parity) is used.
These units employs a sub-set of the programming commands used by standard LMT/LMR modules. In
addition, the command AVALUE is used to set the address number.
As the SI pin is dedicated to serial communication only, the ‘ENABLESERIALMODE’ command string is NOT
required.
To successfully program the unit it must be in active state (RXE high, or TXE low), so provision should be
made to force the unit into this state while programming (either a jumper, or a third pin on the programming
connector, could be used).
GOCHAN aa
AVALUE bbbbb
LOAD aa nnnnn
RVALUE rrrr
<cr>
/
Serially select channel aa, where aa is ch0 to ch31
Set value for unit address
Set value of N register for channel aa, where aa is Channels 0 to 31
Set value for R register
Process entry
Clear all buffers
aa = a two digit channel number from 00 to 31
nnnnn = synthesizer N register value (up to 65535)
rrrr = synthesizer R register value (up to 16383)
bbbbb = unit address (up to 65535)
CXT = N_TX
=
f _RF
f _{Channelspacing}
= ^433.900MHz = 17356
25kHz
R = ^fTCXO = ^13MHz , So R=520
f _{channelspacing} 25kHz
VHF CXT units have 10MHz, not 13MHz reference oscillators:
R = ^fTCXO = ^10MHz , So R=400 (for VHF CXT)
f _{channelspacing} 25kHz
CXR =
N _RX
=
f _RF − 21.4MHz ₌ 433.900MHz − 21.4 _{= 16500}
f _{Channelspacing}
25kHz
Note: A pause of at least 50ms must be allowed between command strings (EEPROM programming time).
Radiometrix Ltd
CXT/CXR – Multi channel Remote Controller Data Sheet
page 7