Radiometrix Ltd

HMT2 Data Sheet

page 4

Serial interface commands

The internal firmware for HMT2 has two versions.

Version 1 is IDENTICAL to our standard LMT2-458-5 (100mW) in all respects

Version 2 is specific to paging applications.

Version 1: programming instruction

2400 baud RS232. 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 fully enable 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, n_txe must be 'low' (active) to enable the unit.

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)

18341

kHz

25

MHz

525

.

458

f

f

N

cing

Channelspa

RF

=

=

=

kHz

MHz

f

f

R

cing

channelspa

TCXO

25

13

=

=

, So R=520

Note:

A pause of at least 50ms must be allowed between command strings (EEPROM programming time).

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.