Radiometrix Ltd

LMT1/LMR1 Data Sheet

page 6

Serial interface commands

2400 baud UART. 8 bit data, no parity, 1 start bit, 1 or 2 stop bits.

Serial data is sent to the unit on one of the parallel channel select pins (P0). It is very important that the unit

does not 'decode' switch bounce in ordinary operation as a command string, or spurious re-writing of the

e2prom will result. For this reason the user must send the 16 character string ENABLESERIALMODE

(followed by a carriage return) to activate the serial command mode before sending any of the command

strings listed below. Command mode is disabled on power down, or on reception of a # character. To

successfully program the unit, it must be enabled ('RXE high (rx) or TXE low (tx)).

GOCHAN aa

Serially select channel aa, where aa is ch0 to ch31

LOAD aa

nnnnn

Set value of N register for channel aa, where aa is Channels 0 to 31

SETPAR

Channel selected by 4 bit parallel inputs (ch0 to ch15 only)

SETSER

Channel selected by most recent GOCHAN operation

RVALUE rrrr

Set value for R register

SINGLE nnnnn

Set value of N for single channel operation.

N value NOT stored in EEPROM

<cr>

Process entry

/

Clear all buffers

#

Disable command mode

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)

For LMT1 Transmitter:

kHz

MHz

f

f

R

cing

channelspa

Xtal

25

10

=

=

, So R=400

6930

25

250

.

173

=

=

=

kHz

MHz

f

f

N

cing

Channelspa

RF

TX

For LMR1 Receiver:

kHz

MHz

f

f

R

cing

channelspa

Xtal

25

13

=

=

, So R=520

Notes: 1. A pause of at least 50ms must be allowed between command strings (EEPROM programming

time).

2. SINGLE mode does not store the N value in EEPROM. Therefore the unit is inoperative after a

power down until either another valid SINGLE command is received, or mode is changed by a

GOCHAN, SETPAR or SETSER command. SINGLE mode is intended for frequency agile

applications.

3. For UK version (173.200 - 173.325MHz band) the following channel assignment is supplied:

CH0: 173.250MHz

CH1: 173.275MHz

CH2: 173.300MHz

CH3: 173.325MHz

CH4 - CH7: 173.225MHz (only used for alarm applications)

CH8 - CH31: 173.325MHz

6074

25

4

.

21

250

.

173

4

.

21

=

−

=

−

=

kHz

MHz

f

MHz

f

N

cing

Channelspa

RF

RX