converse with the RPM3. Let’s
code up a mess of C to put it into
configuration mode. To enter
configuration mode, the RPM3’s
SETUP pin must be logically low
following a reset. That’s pretty
obvious in this SETUP code
if(rloopcounter1 == 0 &&
counter == 1)
rSETUP = 0;
rRESET = 0;
counter = 1024*1024;
rRESET = 1;
counter = 1024*1024;
counter = 2;
rloopcounter1 = 0xFF;
Screenshot 2 captures the
results of our RPM3 reset and the
entry into configuration mode.
Note that the RPM3’s serial
number is displayed. The serial
number is used to uniquely
identify each RPM3. I happen to
have serial numbers 4 and 5.
I manually entered the CONFIG command in
Screenshot 3. The results are default settings.
Maximum throughput may not be desired if the
modems must communicate frequently. The
maximum throughput setting works best when
large amounts of data need to be moved quickly.
The RPM3 transmits in slots otherwise. The slots
and slotsw settings allow other modems to have
a chance to seize the air for short message
Individual RPM3 Units can be clustered into
Sites. RPM3s can only communicate with other
RPM3s that have matching Unit and Site
assignments. There are 16 Unit addresses that
range between 0 and 16. Sites are addressed 0
to 7. Unit and Site addresses are stored in
EEPROM. To allow the use of multipoint services,
the Unit address can be altered without writing
the new address to EEPROM using the ADDR
Flow control is rather obvious here. However,
the SERDLY (Serial Delay) setting is the amount of
time given to an internal timer to allow the full
transmission of the message in the transmit
buffer if the buffer is not full.
SHDN set to ON activates the WAKE/DTR
function. With SHDN (Shutdown) set to ON, we
can control the RPM3’s power consumption by
entering and exiting sleep mode with the DTR
pin. Recall that PIC18F4550’s DTR and the WAKE
I/O lines are the same I/O pin.
The RETRY, ACKMODE, STRTMSG, and
SCREENSHOT 2. We know we’ve entered configuration mode when the
RPM3’s serial number is displayed.
SCREENSHOT 3. These are the default settings. Issuing the
CONFIG command also sets the RPM3’s UART for
three-wire mode (Tx-Rx-Gnd).
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