the data memory.
• NIT — This option selects the altitude units.
• LITE — This option selects whether the display
backlight is off or on.
• TRIG — This option selects whether external
trigger recording is off or on.
• TREV — This option selects normal or reversed
action for the servo-triggered altitude capture.
• STRT — This selects between auto-start recording
• STOP — This selects between auto-stop recording
• ZERO — This selects between auto-zero altitude
• BAUD — This command changes the baud rate
that ZLog uses to communicate with the PC or
• DFLT — This command resets the configuration values
• SAVE — This command will save the changed parameters.
• RST — This command will reset the module.
S1 not pressed
S2 not pressed
S2 not pressed
Normal operating mode —
Altitude Displays altitude;
interfaces with PC.
Configuration mode — Used
“Cfg” to configure the module
via the pushbuttons.
Program mode — Used to
put the module into a
programming mode for
loading new firmware
“Prog” updates to the module. Don’t use this module
until specifically instructed
to do so by the PC
during an update.
S1 not pressed
S2 pressed, or
from PC software
Programming mode allows new firmware to be loaded
into the ZLog module through the PC interface.
• PC Interface — The PC USB cable connects to the ZLog
module’s USB Mini-B connector. When connecting the USB
cable, the ZLog module is also powered through the USB
• PC Software — Permits the downloading of the latest
software and USB drivers.
and Relative altitude. Absolute, of course, refers to your
height above sea level. This reading on the ZLog device
could be off by as much as a few hundred feet due to
varying atmospheric conditions. Barometric pressure
changes caused by approaching storms, etc., influence the
accuracy of any altimeter when attempting to make this
reading. That’s why pilots get a specific reading from the
control tower prior to take-off.
Relative altitude is a measure of the change in height
from a previously reset base altitude. For most applications,
this is quite sufficient. If you make Katmandu your starting
point, then you know you only have another 24,535 feet
to go to reach the top of Everest. Don’t forget to bring
Building the Altoidimeter
Figure 5 represents a typical Altitude versus Time readout
as recorded when the ZLog altimeter captures flight data.
Other scaling would produce similar information if you
were hang gliding, skiing down your favorite slope, and in
any other circumstance where altitude varies with time.
It’s important to note the difference between Absolute
Matt kindly volunteered a unit and, after a little
experimentation, I found that it and a nine volt battery fit
nicely into an Altoids box (Figure 6). Using self-adhesive
hook and loop strips, I fastened the battery to the inside
upper third of the container. Figure 7 shows how snugly it
fits and yet can be removed easily for a battery change.