Digital Compass Solution
HMR3000
The Honeywell HMR3000 is a digital compass module that
provides heading, pitch, and roll outputs for navigation. The
three of Honeywell’s magneto-resistive sensors are oriented in
orthogonal directions plus a fluid tilt sensor are employed to
measure the vector components of the earth’s magnetic field
and a gravitational reference. These solid-state sensors create
a strapdown compass that is both rugged and reliable. The data
output is serial full-duplex RS-232 or half-duplex RS-485 with
1200 to 19,200 data rates.
Applications
include:
Compassing
&
Navigation,
Dead
Reckoning Backup to GPS Systems,
Antenna Positioning, and Land Surveying
Marine Navigation,
A RS-232 development kit version is available that includes a windows compatible demo program, interface cable, AC
adapter, and carrying case.
Honeywell continues to maintain product excellence and performance by introducing innovative solid-state magnetic
sensor solutions. These are highly reliable, top performance products that are delivered when promised. Honeywell’s
magnetic sensor solutions provide real solutions you can count on.
FEATURES & BENEFITS
BLOCK DIAGRAM
V+
Gnd
Pwr
Cond
4
4
4
4
4
4
4
4
High Accuracy, <0.5° with 0.1° Resolution
Wide Tilt Range of
±40°
Up to 20 Updates per Second
NMEA Standard Sentence Outputs
Hard Iron Calibration Routine
HMC1002
µC
ADC
UART
TX
RX
RS-232 or RS-485 Serial Data Interfaces
PCB or Aluminum Enclosure Options
6-15 volt DC Unregulated Power Supply
Interface
HMC1001
2-AXIS
TILT
EEPROM
HMR3000
SPECIFICATIONS
Characteristics
Power Supply
Supply Voltage
Supply Current
Pin 9 referenced to Pin 5 (Ground)
Pin 8 referenced to Pin 5 (Ground)
Vsupply = +6V (Pin 9)
Normal Operation
STOP Mode
SLEEP Mode
Temperature
Operating
Storage
Heading
Accuracy
Resolution
Repeatability
Magnetic Field
Dynamic Range
Resolution
Tilt
Range
Accuracy
(2)
Repeatability
Resolution
Interface
Format
Baud Rate
Update Rate
Mechanical
Weight
Shock
Vibration
PCB Only
PCB and Flanged Enclosure
MIL-STD-810E; TM 516.4 drop test
20 to 2000Hz,
Random for 2 Hours/axis
MIL-STD-810E; TM514.4
*Notes: (1) Calculated values. (2) Device tilt not to exceed 75 degrees, or temporary loss of accuracy occurs.
22
92
30
inches
grams
RS-232 Full Duplex or
RS-485 Half Duplex
Full or Half Duplex
Continuous, per NMEA Sentence
1200
1
19,200
20
bps
Hz
Pitch, Roll
Tilt < 20°
Tilt >= 20°
±0.4
±0.6
±0.2
0.1
degrees
degrees
±40
degrees
degrees
Adjustable
±0.5
gauss range
±1.0
1.0
gauss
milli-gauss
Dip < 50°, Tilt < 20°
Dip < 75°, Tilt < 20°
0.1
±0.3
0.5
(1)
1.5
degrees
degrees
°RMS
Ambient
Ambient, Unpowered
-20
-35
+70
100
°C
°C
35
13
2.0
+6.0
+4.75
+5.0
+15
+5.25
mA
Volts
Conditions
Min
Typ
Max
Units
2
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HMR3000
PIN CONFIGURATION
Pin Number
Pin Name
Description
1
OP/CAL
Operate/Calibrate (open = operate)
2
TD
Transmit Data, RS-485 (B+)
3
RD
Receive Data, RS-485 (A-)
4
RDY/SLP
Ready/Sleep Input (open = ready)
5
GND
Power and Signal Ground
6
RN/STP
Run/Stop Input (open = run)
7
CT/RST
Continue/Reset (open = continue)
8
+5V
Regulated Power Input (+5 volts)
9
V+
Unregulated Power Input (+6 to +15 VDC)
Pin assignments for 9-pin “D” connector. Power input shall be either regulated +5VDC (pin 8) or unregulated +6 to
+15VDC (pin 9). Only one of the two pins shall be connected in a given installation to prevent HMR3000 damage.
RS-232 UNBALANCED I/O INTERCONNECTS
HOST PC
HMR3000
TD
D
RD
R
RD
R
GD
TD
D
GD
RS-485 BALANCED I/O INTERCONNECTS
HOST PC
HMR3000
A-
D
RD(A)
TD(B)
R
D
B+
R
DATA COMMUNICATIONS
The HMR3000 serial communications are governed by a simple asynchronous, ASCII protocol modeled after the NMEA
0183 standard. Either an RS-232 or an RS-485 electrical interface can be ordered. ASCII characters are transmitted and
received using 1 start bit, 8 data bits (LSB first), no parity (MSB always 0), and 1 stop bit; 10 bits total per character. The
baud rate defaults to 19,200 and can be reconfigured to 1200, 2400, 4800, 9600, 19200, 38400 bits per second. The
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HMR3000
HMR3000 supports both standard NMEA 0183 and proprietary messages. Unsolicited NMEA messages are sent by the
HMR3000 in Continuous Mode at the rates programmed in the EEPROM. HMR3000 also responds to all input messages
from the host. An HMR3000 response to a command input may be delayed due to transmission of an unsolicited output.
The host computer must wait for HMR3000 to respond to the last command input before sending another command
message. All communication from and to HMR3000 contain a two-character Checksum Field at the end of the data fields,
and are denoted in the sentences by ‘hh’. The checksum assures the accuracy of the message transmitted. This
checksum is also calculated per NMEA 0183 Standard.
The RS-232 signals are single-ended undirectional levels that are sent received simultaneously (full duplex). One signal is
from the host personal computer (PC) transmit (TD) to the HMR3000 receive (RD) data line, and the other is from the
HMR3000 TD to the PC RD data line. When a logic one is sent, either the TD or RD line will drive to about +6 Volts
referenced to ground. For a logic zero, the TD or RD line will drive to about –6 Volts below ground. Since the signals are
transmitted and dependent on an absolute voltage level, this limits the distance of transmission due to line noise and
signal to about 60 feet.
When using RS-485, the signals are balanced differential transmissions sharing the same lines (half-duplex). This means
that logic one the transmitting end will drive the B line at least 1.5 Volts higher than the A line. For a logic zero, the
transmitting end will drive the B line at least 1.5 Volts lower than the A line. Since the signals are transmitted as difference
voltage level, these signals can withstand high noise environments or over very long distances where line loss may be a
problem; up to 4000 feet. Note that long RS-485 lines should be terminated at both ends with 120-ohm resistors.
Specific measurement descriptions and interface commands are not included in this datasheet but are included in the
companion HMR3000 User’s Guide document.
CIRCUIT DESCRIPTION
The HMR3000 Digital Compass Module contains all the basic sensors and electronics to provide digital indication of
heading and tilt. The HMR3000 has all three axis of magnetic sensors on the far end of the printed circuit board, away
from the connector interface. The HMR3000 uses the circuit board mounting holes or the enclosure surfaces as the
reference mechanical directions. The complete HMR3000 PCB assembly consists of a mother board and the 9-pin D-
connector.
The HMR3000 circuit starts with the Honeywell HMC1001 1-Axis Magnetic Sensor and the HMC1002 2-Axis Magnetic
Sensor elements to provide the X, Y, and Z axis magnetic sensing of the earth’s field. These sensor output voltages are
then amplfied and converted to a digital representation. A microcontroller integrated circuit receives the digitized magnetic
field values (readings) by periodically querying the Analog to Digital Converter (ADC) and performs the necessary offset
value corrections provided by the EEPROM via the calibration routine. This microcontroller also performs the external
serial data interface and other housekeeping functions. The onboard EEPROM integrated circuit also is employed to
retain necessary setup variables for best performance.
A liquid filled two-axis (pitch, roll) tilt sensor is also used to create tilt compensated heading data. This tilt sensor performs
an electronic gimballing function and is normally mounted flat (PCB horizontal) for maximum tilt range.
APPLICATIONS PRECAUTIONS
Several precautions should be observed when using magnetic compasses in general:
•
•
The presence of ferrous materials, such as nickel, iron, steel, and cobalt near the magnetometer will create
disturbances in the earth’s magnetic field that will distort the X, Y, and Z field measurements.
Perming effects on the HMR3000 circuit board need to be taken into account. If the HMR3000 is exposed to
fields greater than 10 gauss, then it is recommended that the enclosure/circuit boards be degaussed for highest
sensitivity and resolution. A possible result of perming is a high zero-field output indication that exceeds
specification limits. Degaussing wands are readily available from local electronics tool suppliers and are
inexpensive. Severe field offset values could result if not degaussed.
NON-FERROUS MATERIALS
Materials that do not affect surrounding magnetic fields are: copper, brass, gold, aluminum, some stainless steels, silver,
tin, silicon, and most non-metals.
4
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HMR3000
HANDLING PRECAUTIONS
The HMR3000 Digital Compass Module measures fields within 1 gauss in magnitude. Computer floppy disks (diskettes)
store data with field strengths of approximately 10 gauss. This means that the HMR3000 is many times more sensitive
than common floppy disks. Please treat the compass with at least the same caution as your diskettes by avoiding motors,
CRT video monitors, and magnets. Even though the loss of performance is recoverable, these magnetic sources will
interfere with measurements.
The fluidic tilt sensor works best when kept near level, and in calm to moderate vibration conditions. If turned upside down
or violently jarred, not all the fluid will immediately return to the bottom of the tilt sensor’s glass ampoule. Accurate tilt and
tilt compensated headings may be unavailable for a minute or two to allow for the fluid to transit to the bottom of the
ampoule.
PCB DIMENSIONS AND PINOUT
CASE DIMENSIONS
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