Radiometrix Ltd

TDH2 Data Sheet

page 6

Programming the TDH2

In order to use all the functions embedded in the TDH2, the user must be aware of the

setup/programming facility, which allow different addresses and frequency channels to be set up, and if

necessary accesses diagnostic test modes.

The TDH2 is programmed through the same RS232 port that is used for sending/receiving data. An

RS232 terminal emulator (such as Aterm or HyperTerminal) is an ideal tool.

To enter program mode, the SETUP pin must be pulled low. In this mode the radio link is disabled,

but characters sent (at 9600 baud, as normal) to the unit are echoed back on the RXD pin.

The unit will only respond to certain command strings:

ADDR0 to ADDR7 <CR>:

These commands set up one of 8 unique addresses.

CHAN0 to CHAN4 <CR>:

These commands select one of 5 preset channels

A TDH2 will only communicate with a unit set to the same address and the same channel.

Address and channel numbers are stored in volatile memory. On power-up the TDH2 reverts to the

default in EEPROM (as supplied this is always address 0 and Channel 0)

SETPROGRAM <CR>:

Writes the current address and current channel into EEPROM as the

new default.

A tilda character (~, ascii 126dec) sent by the unit indicates end of

EEPROM write sequence

(these commands are normally only used for factory diagnostics)

NOTONE <CR>:

Transmit unmodulated carrier

LFTONE <CR>:

Transmit carrier modulated with 8KHz squarewave

HFTONE <CR>:

Transmit carrier modulated with 16KHz squarewave

# <CR>:

Transmitter off

A Carriage Return ‘<CR>’ (00Dhex) should be entered after each command sequence to execute it.

Releasing the SETUP pin to high state returns the TDH2 to normal operation.

Interfacing a microcontroller to TDH2

Figure 6: TDH2 interfaced directly to a microcontroller

TDH2 can be directly interfaced to any microcontrollers. If the microcontroller has a built-in UART, it

can concentrate on its main task and leave the packet formatting, bit balancing and error checking of

serial data to TDH2.