Radiometrix Ltd

MTX2 Data Sheet

page 6

Operation Modes

The MTX2 has three different modes of operation:

1. Parallel. By default the MTX2 operates on one of the four channels selected by the parallel input pins. At

power up, or when a change of parallel input is detected, the current frequency coefficients are loaded from

the eeprom stores corresponding to parallel channels 0-3. The parallel input consists of an inverted 2 bit

binary number applied to P0/P1 (often from a 2 pole switch)

2. Sequential. If a (sequential) channel is programmed over the serial port, the unit sets it's operating

frequency according to this channel number, the programmed table start frequency and the currently

programmed table step size. If the channel is set to zero, the unit returns to default parallel operation.

If the (sequential) channel is programmed into eeprom, the unit will default to this channel at power up

The table can be considered to be a 255 entry table, starting at channel 1, with the frequency incrementing

by the programmed step size for each increment in channel number (it can be seen that, if a 256 entry table

starting with channel zero is desired then programming all the parallel channels to the ch0 frequency, and

the sequential table start value to ch1 will achieve this)

3. Direct. Whenever a frequency coefficient is programmed into the unit, the frequency will change

immediately to this new value regardless of other modes or operation. This is the simplest and most flexible

means of controlling the unit.

If a unit is set in sequential table mode (ie: channel value isn't zero), then direct programming cannot be

used to over-ride the selected channel (executing an @PRG_iiffffff will just set up a set of frequency

coefficients ready to be written to rom. It won't change the actual operating frequency)

Serial interface commands

MTX2 serial interface consists of an inverted RS232 datastream (9600 baud, 1+8+1, no parity) applied to the

EN pin (the idle state of the interface will turn the transmitter on)

Every command string starts with the phrase "@PRG_"

The characters in a command string must not be separated by more than 5mS (so typing individual

characters on a terminal keyboard will NOT work), but a pause of at least 10mS is required between

commands (more following a BURN_ROM command. In this case a much longer idle period, of 50mS at

least, is needed for eeprom programming)

Frequency setting commands

Commands

Function

@PRG_iiffffff <cr>

sets the current (temporary) frequency

iiffffff is an 8 digit hexadecimal number (4 bytes):

ii is the 1 byte "integer" coefficient

ffffff is the 3 byte "fraction" coefficient

Frequency (in MHz) = 6.5 x integer + 6.5 x (fraction/2^19)

The component (fraction/2^19) must be in the range 1-2

@PRG_BURN_CH0 <cr>

write current frequency into channel 0 eeprom

@PRG_BURN_CH1 <cr>

write current frequency into channel 1 eeprom

@PRG_BURN_CH2 <cr>

write current frequency into channel 2 eeprom

@PRG_BURN_CH3 <cr>

write current frequency into channel 3 eeprom

(these functions do NOT program band/power/offset values)