IM1800 Applications
serial interface should remain unconnected. The
IM1800 virtual serial port USB interface is based on the
Silicon Labs CP2101 IC. The CP2101 drivers can be
downloaded from www.silabs.com. After the correct
driver has been installed on a host PC, the USB inter-
face will appear as a serial port.
The IM1800 is a companion interface board for the
DM1800 series transceiver modules. It has two uses:
First, the IM1800 can be used as a general purpose in-
terface for DM1800 series transceiver modules. For this
application, the IM1800 provides a captured screw I/O
terminal block, a virtual serial port USB interface, and a
Bread Boarding Area
choice of USB, coaxial plug or terminal block for the DC Referring to Figure 1, the IM1800 bread boarding area
power supply input. For DM1800 base stations and field is supplied with ground connections on eyelet Row 10
nodes, the IM1800 supports serial communications (vertical row of eyelets on right side), VOUT on eyelet
through the virtual serial port USB interface, or by direct Row 3, and VIN on eyelet Row 2. VOUT and the I/O
connection to the USART on the DM1800 module.
signals from the DM1800 are also provided in two loca-
tions on Row 1. Refer to the table on Pages 3 and 4 for
details. Note that the DM1800 can provide up to 10 mA
for supplying external circuitry. Additional power can be
provided by adding a 3 V regulator in the bread board-
ing area and running it from VIN. Take caution not to
operate circuitry from VIN that directly interfaces the
DM1800 I/O signals to avoid damaging the DM1800
and/or IM1800. Note that any components placed on
the bread boarding area directly under where the
DM1800 module plugs in must be no taller than 0.1
inch.
Second, the IM1800 can be used as a development
platform for applications where a DM1800 series trans-
ceiver will be installed a customer’s board. In addition to
the features listed above, the IM1800 provides a con-
nector strip for jumpering a flat cable to a customer’s
board (or for a logic analyzer/oscilloscope connection),
and a “bread board” area for building and testing inter-
face circuits.
Power Supply Options
The IM1800 will accepts an external DC power supply
voltage in the range of 2.6 to 14 V (3.1 to 14 V for ex-
tended temperature operation). This voltage is routed to
the 3 Vdc regulator on the DM1800 transceiver (see
description of J2-3 on Page 3 for VOUT characteristics).
The external power supply voltage can be connected to
VIN on terminal block J2 or to the coaxial power con-
nector J6. The IM1800 can also be powered from the
USB connector J1. When the IM1800 is powered from
the USB connector, no connection should be made to
the VIN terminal on terminal block J2 or to the coaxial
power connector J6.
I/O and Power Supply Precautions
Note that all analog and digital input signals must be
within the range of 0 to VOUT. Applying a signal outside
of this range may damage the DM1800 and/or IM1800.
External DC power supplies must be in the range of 2.6
to 14 V. Suitable external power supplies include batter-
ies and transformer isolated, regulated DC power sup-
plies. Be cautious when using unregulated “wall
transformer” DC supplies. The output voltage of these
unregulated supplies can be much higher than the
nameplate value when powering low current loads.
Serial Port Options
Note: the IM1800 is equipped with a programming con-
®
nector compatible with a Microchip MPLAB ICD 2. Ex-
The IM1800 provides direct connections to the DM1800
transceiver module USART on terminal block J2. Note
that the DM1800 USART I/O is 3 V CMOS logic. Alter-
nately, the serial port on a DM1800 can be interfaced
through the serial port-USB bridge IC on the IM1800.
Only one interface should be used at a time; the other
cept in special circumstances, however, all DM1800
transceiver modules are shipped pre-programmed. Re-
programming a pre-programmed DM1800 transceiver
module will void the warranty and any regulatory certifi-
cations of the module.
2
RFM [ RF MONOLITHICS, INC ]
