HMR3200/HMR3300
SENSOR PRODUCTS
DIGITAL COMPASS SOLUTIONS
Features
1 Heading Accuracy, 0.1 Resolution
0.5 Repeatability
60 Tilt Range (Pitch and Roll) for HMR3300
Small Size (1.0" x 1.45" x 0.4"), Light Weight
Compensation for Hard Iron Distortions, Ferrous
Objects, Stray Fields
15Hz Response Time
-40 to 85C Operating Temperature Range
6-15 volt DC unregulated or 5 volt regulated supply
General Description
The Honeywell HMR3200/HMR3300 are electronic
compassing solutions for use in navigation and
guidance
systems. Honeywell's magnetoresistive
sensors are utilized to provide the reliability and
accuracy of these small, solid state compass designs.
These compass solutions are easily integrated into
systems using a UART or SPI interface in ASCII
format.
The HMR3200 is a two-axis compass, and can be used
in either vertical or horizontal orientations.
The HMR3300 is a three-axis, tilt compensated
compass that uses a two-axis accelerometer for
enhanced performance up to a 60 tilt range.
APPLICATIONS
Block Diagram
Compassing & Navigation
Attitude Reference
Satellite Antenna Positioning
Platform leveling
GPS Integration
Laser Range Finders
C
xout
yout
2-axis
accel
Multi-ADC
HMC1022
HMC1021
Volt
Reg
Vcc
Vcc
Vcc
V+
EEPROM
SCK
SDI
SDO
CS
CAL
TX
RX
SP
I
UA
R
T
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HMR3200/HMR3300
SENSOR PRODUCTS
SPECIFICATIONS
Characteristics
Conditions
Min
Typ
Max
Units
Heading
Accuracy
Level
0 to 30 (HMR3300 only)
30 to 60 (HMR3300 only)
1.0
3.0
4.0
deg RMS
Resolution
0.1
deg
Hysteresis
HMR3200
HMR3300
0.1
0.2
0.2
0.4
deg
Repeatability
HMR3200
HMR3300
0.1
0.2
0.2
0.4
deg
Pitch and Roll
(HMR3300 only)
Range
Roll and Pitch Range
60
deg
Accuracy
0 to 30
30 to 60
0.4
1.0
0.5
1.2
deg
Null Accuracy*
Level
-20 to +70C Thermal Hysterisis
-40 to +85C Thermal Hysterisis
0.4
1.0
5.0
deg
Resolution
0.1
deg
Hysteresis
0.2
deg
Repeatability
0.2
deg
Magnetic Field
Range
Maximum Magnetic Flux Density
2
gauss
Resolution
0.1
0.5
milli-gauss
Electrical
Input Voltage
Unregulated
6
-
15
volts DC
Current
HMR3200
HMR3300
18
22
20
24
mA
mA
Digital Interface
UART
ASCII (1 Start, 8 Data, 1 Stop,
0 Parity) User Selectable Baud Rate
2400
-
19200
Baud
SPI
CKE = 0, CKP = 0 Psuedo Master
Update
Continuous/Strobed/Averaged
HMR3200
HMR3300
15
8
Hz
Connector
In-Line 8-Pin Block (0.1" spacing)
* Null zeroing prior to use of the HMR3300 and upon exposure to temperature excursions beyond the Operating
Temperature limits is required to achieve highest performance.
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HMR3200/HMR3300
SENSOR PRODUCTS
Characteristics
Conditions
Min
Typ
Max
Units
Physical
Dimensions
Circuit Board Assembly
25.4 x 36.8 x
11
mm
Weight
HMR3200
HMR3300
7.25
7.5
grams
Environment
Temperature
Operating (HMR3200)
Operating (HMR3300)
Storage
-40
-20
-55
-
-
+85
+70
+125
C
C
C
P
in Configuration
Pin Number
Pin Name
Description
1
SCK
Serial Clock Output for SPI Mode
2
RX/SDI
UART Receive Data/SPI Data Input
3
TX/SDO
UART Transmit Data/SPI Data Output
4
CS
Chip Select for SPI Mode (active trailing edge)
5
CAL
Calibration ON/OFF Input (active trailing edge)
6
+5VDC*
+5 VDC Regulated Power Input
7
GND
Power and Signal Ground
8
+V*
Unregulated Power Input (+6 to +15 VDC)
*Note: Use either pin 6 (+5VDC) or pin 8 (+V) to power the circuit board. Hold the board with pin header edge close to
you and pins pointing DOWN. Then PIN 1 is the left most pin.
CIRCUIT DESCRIPTION
The HMR3200/HMR3300 Digital Compass Solutions include all the basic sensors and electronics to provide a digital
indication of heading. The HMR3200 has all three axis of magnetic sensors on board, but allows the user to select
which pair of sensors for compassing (flat or upright). The HMR3300 uses all three magnetic sensors plus includes
an accelerometer to provide tilt (pitch and roll) sensing relative to the board's horizontal (flat) position.
The HMR3200/HMR3300 circuit starts with Honeywell HMC1021 and HMC1022 single and two-axis magnetic
sensors providing X, Y, and Z axis magnetic sensing of the earth's field. These sensors are supplied power by a
constant current source to maintain best accuracy over temperature. The sensor output voltages and constant
current sensor supply voltage are provided to multiplexed Analog to Digital Converter (ADC) integrated circuit. A
microcontroller integrated circuit periodically queries the multiplexed ADC and performs the offset corrections and
computes the heading. This microcontroller also performs the external serial data interface and other housekeeping
functions such as the calibration routine. An onboard EEPROM integrated circuit is employed to retain necessary
data variables for best performance.
For the HMR3300, an additional pair of data inputs from the 2g accelerometer is received by the microcontroller.
These tilt inputs (pitch and roll) are added to sensor data inputs to form a complete data set for a three dimensional
computation of heading.
The power supply for the HMR3200/HMR3300 circuit is regulated +5 volt design allowing the user to directly provide
the regulated supply voltage or a +6 to +15 volt unregulated supply voltage. If the unregulated supply voltage is
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HMR3200/HMR3300
SENSOR PRODUCTS
provided, then the linear voltage regulator integrated circuit drops the excess supply voltage to a stable +5 volts. The
power supply is a dual ground (analog and digital) system to control internal noise and maximize measurment
accuracy.
PHYSICAL CHARACTERISTICS
The circuit board for the HMR3200/HMR3300 Digital Compassing Solutions is approximately 1.45 by 1 inches. An 8-
Pin header protrudes down on one edge of the board for the user interface or the demo board. The header pins
extend 5/16" below the board plane with the bottom-side mounted magnetic sensor integrated circuits (HMC1021
and HMC1022) extending 3/16" below the board plane. Components on the top-side have a maximum height of 1/8".
Figure 1 shows a typical circuit board with dimensions.
1.00"
1.45"
1.22"
REF PINS
(2)
1
2
3
4
5
6
7
8
8-PIN
HEADER
(0.1" SPACING)
.037"
0.15"
.094"
.037"
1.00"
1.45"
1.22"
REF PINS
(2)
1
2
3
4
5
6
7
8
8-PIN
HEADER
(0.1" SPACING)
.037"
0.15"
.094"
.037"
Figure 1
Application Notes
UART COMMUNICATION PROTOCOL
HMR3200/HMR3300 modules communicate through ASCII characters. The data bit format is 1 Start, 8 Data, 1
Stop, and No parity bits. Asynchronous communication has the complete menu of commands.
OPERATIONAL COMMANDS
Syntax: *X<cr><lf>
Sends command for an operational mode change
Heading Output Command
*H<cr><lf>
Selects the Heading output mode (factory set default). This configuration is saved in non-volatile memory.
Format: Heading
Eg: 235.6
Magnetometer Output Command
*M<cr><lf>
Selects the magnetometer output mode. This configuration is saved in non-volatile memory.
Format: MagX, MagY, MagZ
Eg: 1256, -234, 1894
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HMR3200/HMR3300
SENSOR PRODUCTS
Compass Orientation (HMR3200 only)
*L<cr><lf>
Heading calculation is done assuming the compass is level.
*U<cr><lf>
Heading calculation is done assuming the compass is upright (connector end down).
These orientation commands are saved in non-volatile memory.
Starting and Stopping Data Output
*S<cr><lf>
The data output will toggle between Start and Stop each time this command is issued (factory set default is
Start, first Start/Stop command will stop data output).
Query
*Q<cr><lf>
Query for an output in the currently selected mode (Mag/Head). Allowed only in Stop data mode.
Roll Axis Re-Zero
*O<cr><lf>
Allows the user to zero the roll output. This command should only be issued when the roll axis is leveled
( 0.3).
Pitch Axis Re-Zero
*P<cr><lf>
Allows the user to zero the pitch output. This command should only be used when the pitch axis is leveled
( 0.3).
Averaged Output
*A<cr><lf>
Same result as the query command except that the data is the result of an averaging of the last 20 readings.
Allowed only in Stop data mode.
Split Filter Toggle
*F<cr><lf>
Toggles the split filter bit. The parameter setting is saved in the EEPROM immediately. Requires power
cycling or a reset command to activate.
Reset
*R<cr><lf>
Resets compass to power-up condition.
User Calibration
*C<cr><lf>
Command to be issued to enter and exit the calibration mode.
Once in the calibration mode, the device will send magnetometer data appended by a "C" character to indicate the
Calibration Mode operation.
Eg. 123,834,1489,C
During the calibration procedure, the compass and the platform to which the compass is attached is rotated at a
reasonably steady speed through 360 degrees. This process should at least take one minute for best accuracy. In
case of HMR3200, the rotation should be in the horizontal flat plane. For HMR3300, the rotation should include as
much pitch and roll orientations possible. At the completion of the rotations, issue another *C<cr><lf> to exit the
calibration mode.
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