Radiometrix Ltd

HVR2 Data Sheet

page 4

Serial interface commands

HVR2 frequency/channel can be serially configured using HyperTerminal or any other terminal

program configured with following setup:

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 (S0). 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 EEPROM will result. For this reason the user must send the 16 character string

ENABLESERIALMODE 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.

Owing to the complex nature of the DDS programming in the HVR2, the user does not have direct

access to the synthesizer registers (as is the case in the simpler RLC2). Instead, the user has a table of

32 channels (accessible by parallel port, or by the GOCHAN command). Each of these channels can be

assigned to one of the HVR2's pre-set frequencies (433.05 - 434.775MHz)

(note: the parallel port accesses the higher 16 channels, from 16-31, as if a '5th parallel select bit' is

always ‘low’).

GOCHAN aa

Serial select of channel aa (0 to 31) (stored in non-volatile EEPROM)

HOPPER nn

Temporary select of frequency number nn (0 to 69)

LOAD aa nn

Set a frequency (nn) for channel aa (channels 0 to 31)

SETPAR

Channel selected by 5 bit parallel inputs (4pins S0-S3 + S4 always high)

SETSER

Channel selected by most recent GOCHAN operation

<cr>

Process entry

/

Clear all buffers

#

Disable command mode

aa = a two digit channel number from 00 to 31 (values 00-15 can only be selected by a GOCHAN

command)

nn= abstract ‘frequency number’ relating to one of the pre-set operating frequency

Channel frequency = 433.05 + (nn x 0.025) MHz

For example: nn = 01 relates to a channel frequency of 433.075MHz, and the commnd:

LOAD 00 01 will set channel number 0 to 433.075MHz

Note:

A pause of at least 25ms must be allowed between command strings (EEPROM programming

time).

The HVR2 has no equivalent to the RLC2 'SINGLE' command. The 'HOPPER' command

provides some similarity, but on power up (or SETPAR, SETSER or GOCHAN command) the

radio reverts to ordinary operation.