IM1800 Applications

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

choice of USB, coaxial plug or terminal block for the DC

power supply input. For DM1800 base stations and field

nodes, the IM1800 supports serial communications

through the virtual serial port USB interface, or by direct

connection to the USART on the DM1800 module.

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.

Serial Port Options

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

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.

Bread Boarding Area

Referring to Figure 1, the IM1800 bread boarding area

is supplied with ground connections on eyelet Row 10

(vertical row of eyelets on right side), VOUT on eyelet

Row 3, and VIN on eyelet Row 2. VOUT and the I/O

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 addinga3V 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.

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.

Note: the IM1800 is equipped with a programming con-

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.

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