On the cable that I made, I tied
both pin 1 and pin 5 together.
At this point, you don’t need to
connect the PPS or RX pins.
Of all the modules tested, I
found the EM-406 to be the most
sensitive and easiest to use. I
was able to lock on to four or
five satellites in my basement
workshop. At times, even the
WAAS receiver kicked in when
in the basement. In normal
operation outside, I found the
EM-406 to be very accurate
once the WAAS receiver
connected. The only downside
was the lack of an external
antenna connector. There is no
need to send commands to set
up the module, so only the TX
lead is needed for the interface.
I also liked the fact that the
module could be operated at
five volts. This makes the
interface to both the PC and
microcontroller very easy.
I covered the connector
modification in Part 2 of this series.
Connect the pins on the connecter as
shown in Figure 6. Unlike the EM-406,
we need to connect the RX lead as
we will need to send some setup
commands to the EB-85.
time. This can be a double-edged
sword since you have to service the
UART more often in order to keep
from dropping data.
leads. Attach the red and black
wires to a two-pin header and the
green and white leads to a two-pin
header as shown in Figure 7. The
connection to the Workboard is
shown in Figure 8.
Etek EB-85A Observations
The EB-85 operates with five volts
as well, so it is one of my favorites.
While it does support more channels
than the EM-406, I was only able to
lock on to seven or eight satellites at
a time so I did not see any advantage
over the EM-406. The EB-85 does
need some setup to turn off some of
the messages that are not needed
and to turn on the WAAS receiver.
The EB-85 sports a much faster
default baud rate so more data can
be received in a shorter period of
The GPSSlim236 microcontroller interface is simpler than one would think.
The mini USB connector
on the unit is actually a
TTL interface. With this
connector, you can both
power/charge the unit and
pull data from the receiver. I
purchased a $3 mini USB
cable from www.cyber
guys.com (part #131 0995)
for the interface.
Cut off the large
connector and strip the
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