2 The Host Interface
2.1 SIGNALS
The connection to the RPM is a full duplex serial interface supporting baud rates from 600bps to
115200bps. Additional control signals are provided to assist in flow control, configuration and power
saving in the RPM1.
Figure 5: Physical dimensions and pinouts
Pin name
RF GND
RF
Pin
1, 3
2
Pin Function
RF signal ground
RF signal
In/Out
Description
BNC casing/coax braid connection
Input or Output Antenna pin/coax core connection
RXSELCT
4
Receiver Select
Input
or Output
Internal RF Receiver Enable to BiM1
or RF Receiver Active Indicator
TX SELECT
TXD/AF
5
7
Transmitter Select
Input
or Output
Input
or Output
NC
Internal RF Transmitter Enable to BiM1
or RF Transmitter Active Indicator
Transmitted Packetised Data to BiM1
Analogue Demodulated signal from BiM1
Internal data line between RPM and FRPC
Transmitted Data
or demodulated signal
FRPC Data line
8
D3
9
FRPC Data line
Preamble Detect
FRPC reset
Receive Acknowledge
Receive Request
Reset
NC
Output
NC
Internal data line between RPM and FRPC
Valid preamble indicator
Resets FRPC which also isolates BiM1
RPM to FRPC download Request Acknowledge
Valid Data packet indicator
D2
SIGNAL
RST
RXA
RXR
RESET
SETUP
10
11
12
13
14
15
NC
Output
Input
Input
Input
Input
Output
Output
Input
Input
-
Hardware reset of the RPM1
Enter Setup
Enter RPM1 configurator after a RESET
Wakes RPM1 when low, shuts down when high
Host (DTE) to RPM1 serial transmit data
RPM1 to host (DTE) serial received data
Hardware flow control of data from host (DTE)
Force the RPM1 serial interface to 9600bps
+5VDC or +3.3VDC
WAKE/DTR 16
Wake or Shutdown
Serial transmitted data
Serial Received data
Clear To Send
Force 9600bps
Vcc Supply
TXD
RXD
CTS
DEFAULT
VCC
17
18
19
20
21
6, 22
GND
Ground
Supply Ground internally connected to RF GND
notes: 1. RXD/TXD lines are true data
2. Active low SETUP, DEFAULT inputs require external 10kΩ pull-up to VCC.
3. Logic levels are 5V CMOS unless 3.3V variant is used.
4. WAKE pin should be pulled to ground if DTE cannot provide DTR signal
5. TXSELECT, RXSELECT, SIGNAL, RXR, CTS can be connected to LEDs via 1kΩ series resistors
2.2 RADIO
PACKET MODEM RESET
RESET
The Reset signal is internally pulled up to Vcc via a 10kΩ resistor. A reset aborts any transfers in
progress and restarts the RPM1.
HOST DRIVEN RESET
Minimum low time: 1.0 µs, after reset is released (returned high). The host should allow a delay
1ms after reset for the RPM1 to initialise itself.
Radiometrix Ltd.
VHF Narrow Band FM Radio Packet Modem
page 4
RADIOMETRIX [ RADIOMETRIX LTD ]
