Radiometrix Ltd
TDH2 Data Sheet
page 7
Serial data should be in the following format:
1 start bit, 8 data bits, no parity, 1 or 2 stop bits
9600bps
0V=low, 5V=high
STATUS pin can be connected to one of the port pins which can generate an interrupt on low-to-high
transition (e.g. RB0/INT pin in the PIC). This can be used to enter a receive sub-routine to download
data received from remote TDH2. Therefore, the host does not need to wait in a loop for a packet.
Range test and site survey can be carried out by connecting an LED on the STATUS pin. Every time,
TDH2 is within range to receive valid data, the LED will flicker.
Interfacing RS232 port to TDH2
Figure 7: TDH2 interfaced to an RS232 port via an RS232 line driver/receiver
STATUS pin in this can be connected to CTS, DSR and DCD pin to simulate a flow control signal.
TDH2 is capable of continuously streaming data at 9600bps. Therefore, STATUS pin is not asserted to
stop the Host from sending data as in normal RTS/CTS flow control method, but merely to warn the
host that there is already data in the receive buffer which need to be downloaded before sending any
more data.
Some DTE hosts assert DTR signal when they are active and this can be used via RS232 line receiver to
enable TDH2. Otherwise the ENABLE must be physically pulled-low to activate the TDH2.
NOTE:
An interface board (with MAX232 type buffer, 9 way D connector, 5V voltage regulator and SMA RF
connector) is available. This board is 61mm x 33mm in size.
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