linearization, and temperature
compensation. Outputs a signal
proportional to air pressure.
• 16-bit Analog-to-Digital Converter —
Transforms the analog info from the
sensor into the necessary digital
representation for further processing
by the microcontroller.
• Microcontroller — Eight-bit 8051
with onboard Flash and RAM. Reads
the A/D, calculates altitude from pressure, displays the altitude, and records
to EEPROM (electronically erasable
programmable read-only memory).
• LCD Display — Four-digit LCD with
inter-integrated circuit interface.
• 32K EEPROM — For storing
recorded altitude data.
• USB/Serial Converter — Interface
to PC or external microprocessor for
configuring, reading/writing altitude
data, logging real-time altitude, etc.
• Buttons — Allow user to configure
the altimeter setup using the LCD.
• LEDs — Indicate USB link, power,
recording on, and flashes with
• Voltage Regulator — Converts input
voltage to regulated 3.3V for the
system. Takes input either from the
USB port if attached or an external
battery (or R/C receiver channel).
Dimensions 1.57” x 0.92” x 0.37” 40 mm x 23. 4 mm x 9. 4 mm
Weight Eight grams
Temperature Range1 0°C– 60°C (pressure sensor ±1.5% accuracy) - 10°C– 60°C (pressure sensor ± 3.0% accuracy)
Input Voltage Range 4.0– 30.0 volts DC
Input Current 16 milliamps (backlight on). 13 milliamps (backlight off).
Measured: 52,000 feet ( 15,849 meters)
Maximum Altitude1 Displayed: 9,999 feet/yards/meters
Recorded: 32,767 feet ( 9,987 meters)
Measured (absolute): -2,000 feet (-656 meters)
Minimum Altitude1 Displayed (relative or absolute): -999 feet/yards/meters
Recorded (relative or absolute): - 32,512 feet (- 9,909 meters)
Memory Capacity 16,378 samples
Acquisition 100 milliseconds/sample up to one hour/sample in
Sampling Rates 100 millisecond increments
Timing Accuracy ±2.5%
Altitude Resolution One foot (one meter)
1Specifications taken from component ratings and system limits; may
not have been tested to the full extent of the specified ranges.
altitude and maximum altitude.
The display differentiates the two by
flashing the maximum altitude. The
maximum altitude is the greatest
altitude recorded since the module
was turned on.
• Zero Altitude — The current altitude
to be set as the zero point with all
subsequent readings being relative
to that point.
• Recording Start/Stop — Store
altitude data in memory. The number
of data sets is limited only by the
amount of free data storage memory
Config mode allows the module
to be configured using the two
• RATE — This option selects the
• CLR — This command clears
Figure 4 is a representation of the
placement of all of these components.
The module operates in one of
three modes, depending on the
position of the pushbutton switches
at startup. These modes are shown in
Normal mode is how the module
will be used most of the time. In this
mode, the module continuously
displays altitude. The display updates
four times per second. Note that
this does not necessarily correlate to
the sampling period. The following
controls are available in normal
• Current/Maximum Altitude Select —
Toggles the display between current
November 2008 59