TCM2 Basic Technical Information

About the TCM2

The TCM2 is a state-of-the-art low-power, high-performance Electronic Compass Sensor Module. The TCM2 combines, for the first time ever, a revolutionary three-axis magnetometer and a high-performance two-axis tilt sensor in a package that is smaller and consumes less power than any other compass module currently available. The TCM2’s elimination of a mechanical gimbal is unique among electronic compasses. All compasses must be referenced to level to be accurate, but instead of using a clumsy universal joint or fluid bath to hold its sensors level, the TCM2 uses a highly accurate inclinometer (tilt sensor) to allow the microprocessor to mathematically correct for tilt. This electronic gimballing eliminates moving parts and provides more information about the environment: pitch and roll angles and three dimensional magnetic field measurement in addition to compass output. This extra data allows the TCM2 to provide greater accuracy in the field by calibrating for distortion fields in all tilt orientations, providing an alarm when local magnetic anomalies are present, and giving out-of-range warnings when the unit is being tilted too far. At the heart the TCM2, its patented magneto-inductive magnetometers are the first major advance in compass magnetometers since the fluxgate was invented in the 1930’s. Their solenoidal, single-winding construction provides a more compact, reliable, and cost-effective solution than torroidal fluxgates. They also consume roughly an order of magnitude less power. Their dynamic range and sensitivity can be easily tailored to the exact needs of any application. The TCM2’s magnetometers provide a very large dynamic range and hence can be calibrated for systems that have extremely strong fields, such as military vehicles. The TCM2’s advantages make it suitable for many applications, including: • GPS systems requiring backup azimuth data • Automobile and marine navigation systems • Virtual reality input devices • Robotics • Original equipment instrumentation for automobiles • Aircraft compasses and avionics systems • Scuba dive computers and compasses • Oceanographic buoys and data stations • Tracking animal's migration patterns.With its many potential applications, the TCM2 provides a command set designed with flexibility and adaptability in mind. Many parameters are user-programmable, including reporting units, a wide range of sampling configurations, output damping, and more. We hope the TCM2 will help you to achieve the greatest performance from your target system. Thank you for selecting the TCM2.

Differences between the TCM1 and TCM2

The TCM2 is backward compatible with the TCM1. The following features have been added to make the TCM2 much more useful and robust for all applications. • 20°, 50° and 80° inclinometer values• 16 Hz and 30 Hz output rates, default is now 16Hz, not 8Hz.• Digital damping • Fine control of the clock rate • Adjustable clipping values for the inclinometer • Maximum baud rate is 38,400 • Magnetic fields output has 0.01 uT resolution

Electrical connections

The TCM2 utilizes a standard straight-post, non-polarized 10-pin header for power and data connections. The header is MOLX 22-03-2101style, with 0.100” centers. The mating receptacle is MOLX 22-01-3107, or equivalent. The pin-out for this connector is diagrammed below. Note:• Analog output is available on all TCM2 models.• Mouse mode is for Virtual Reality applications.• Supply voltage may either be supplied as 6-25V unregulated, or 5V regulated (±5%). Do not apply power to both power pins simultaneously.• The Data Ground, pin 7 of the connector, should be connected to RS232 ground. • The RxD receive pin, pin 4, accepts voltages from -15v to 15v. • The TxD transmit pin outputs -5v to 5v. These ranges are compatible with most RS232 transceiver chips. • The serial communications interface is RS232, with the following parameters: 8 data bits, 1 start bit, 1 stop bit, no parity. Transmit voltages are ±5V; receive voltages are ±5V minimum, ±15V maximum. The baud rate may be configured from 300-38400 baud.

Calibration for hard-iron distortion fields

After installation, the TCM2 can be calibrated for local magnetic fields present in the host system. The TCM2 can fully compensate for “hard-iron” magnetic anomalies–sources of static magnetic fields. The User Calibration procedure, described in section 3.8, provides a quick and easy means of canceling the effects of these local magnetic anomalies. Calibration data is stored in the TCM2’s non-volatile EEPROM memory so that it is preserved after power-down.

Evaluation instructions

The most convenient means of experimenting with the TCM2 is by connecting the TCM2 to a power supply and IBM-AT compatible PC computer using the cable supplied with the evaluation kit. You may then use the PC to configure and communicate with the TCM2.

TCM2 default configuration

The TCM2 is configured to output compass, pitch and roll data at 9600 baud. It will be in Standby mode. All units will be configured for the default units. Please refer to appendix B for the command list and default parameter values.

Connecting the TCM2

Refer to section 2.4 for information on the TCM2’s electrical connections. A ttaching a single 9V battery to the unregulated supply and power ground pins of the TCM2’s connector (pins 2 and 3 respectively) is a convenient means of applying power to the TCM2. The three signals used for RS232 should be connected to the corresponding pins on one of your PC’s COM ports. On a standard DB25 COM port connector, make the following connections:COM Port TCM2 ConnectorPin # Signal Pin # Signal2 TxD 4 RxD3 RxD 5 TxD7 Ground 7 Data ground4* RTS 6* Mouse (*This connection is only necessary if you plan to use the TCM2 as a headtracker emulating a mouse)On a standardPC's DB9 COM port connector, make the following connections:COM Port TCM2 ConnectorPin # Signal Pin # Signal2 TxD 5 TxD3 RxD 4 RxD5 Ground 7 Data ground7* RTS 6* Mouse (*This connection is only necessary if you plan to use the TCM2 as a headtracker emulating a mouse)Note that some COM ports have pins 2 as TxD and 3 as RxD.

Cable specifications

The TCM2 Evaluation Kit contains a cable to connect to the TCM2. On one end of the cable is the connector needed to mate to the TCM2, AMP style MTA-100 (AMP P/N 640620-8, or equivalent). The cables wires are color coded as indicated below:

Color              Connector Pin #    Signal             

Orange                     1          Vsupply            
                                      (regulated)        

Red                        2          Vsupply            
                                      (unregulated)      

Black                      3          Ground (power)     

Blue                       4          RxD (RS232)        

Yellow                     5          TxD (RS232)        

White                      6          Mouseoutput        

Green                      7          Data ground        

Brown                      8          Analog output      

Purple                     9          Analog output2     

Gray                       10         Data Ground        

Communicating with the TCM2

Once the TCM2 is powered up and the RS232 connection is made with one of the PC’s COM ports, you may begin swapping ASCII serial data with the TCM2. The most direct means is to run any modem or terminal emulation software, specify the COM port that you have the TCM2 connected to and the default baud rate for the TCM2 (9600 baud), and begin typing commands. Remember that the TCM2 does not echo characters by default, so you may wish to select the echo output option in your terminal emulation program. zcode>“ denotes all the characters for an error code string.

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