2 The Host Interface
2.1 S
IGNALS
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
RXSELCT
TX SELECT
TXD/AF
Pin
1, 3
2
4
5
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
6, 22
Pin Function
RF signal ground
RF signal
Receiver Select
Transmitter Select
Transmitted Data
or demodulated signal
FRPC Data line
FRPC Data line
Preamble Detect
FRPC reset
Receive Acknowledge
Receive Request
Reset
Enter Setup
Wake or Shutdown
Serial transmitted data
Serial Received data
Clear To Send
Force 9600bps
Vcc Supply
Ground
In/Out
Input or Output
Input
or Output
Input
or Output
Input
or Output
NC
NC
Output
NC
NC
Output
Input
Input
Input
Input
Output
Output
Input
Input
-
Description
BNC casing/coax braid connection
Antenna pin/coax core connection
Internal RF Receiver Enable to BiM1
or RF Receiver Active Indicator
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
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
Hardware reset of the RPM1
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
Supply Ground internally connected to RF GND
D3
D2
SIGNAL
RST
RXA
RXR
RESET
SETUP
WAKE/DTR
TXD
RXD
CTS
DEFAULT
VCC
GND
notes:
1. RXD/TXD lines are true data
2. Active low SETUP, DEFAULT inputs r
equire 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 1k
Ω
series resistors
2.2 R
ADIO
P
ACKET
M
ODEM
R
ESET
R
ESET
The Reset signal is internally pulled up to Vcc via a 10kΩ resistor. A reset aborts any transfers in
progress and restarts the RPM1.
H
OST 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 ]
