User's Manual

Interface specification: Pin descriptions 37
RIM 902M OEM Radio Modem – Integrator’s Guide
There is no “best” protocol. The MASC or RAP protocol is used strictly for the
link between the radio modem and the computing device, and does not have
any influence on the speed or reliability of communication between the radio
and the Mobitex network. The RIM engineering development team (e-mail:
[e-mail]) can help you select the protocol most suited to your needs.
Pin descriptions
All input and output lines are 3.0 volt logic; however, they will also be able to
drive 3.3 volt systems. Further, all input lines to the serial port are 5.0 volt
tolerant and outputs will be capable of driving 5.0 volt systems provided the V
IH
of these pins is less than 2.5 volts. Pins 1 through 4, the general purpose I/O
lines, are strictly a 3.0 volt interface; they are not 5.0 volt tolerant.
This section describes the purpose of each of the 22 lines that comprise the
serial interface of the RIM 900 OEM radio modem. The symbol ~ before the
label indicates that line is an active low digital signal.
Pins 1, 2, 3, 4, 13, and 22 are designed for future use and must be left
disconnected. All other unused inputs to the radio should be tied to ground, and
any unused outputs from the radio should be left disconnected.
Pin 5 ~MSG ~Message Waiting
This is an output from the radio.
The active state of this line is low, and indicates that the radio has received a
message (packet) from the network, which has not been delivered to the device
application yet. This line continues to remain active until the application
acknowledges receiving the packet.
When the radio’s receive buffer is full, this line will be inactive (high).