The Honeywell HMC6352 is a fully integrated compass
module that combines 2-axis magneto-resistive sensors
with the required analog and digital support circuits, and
algorithms for heading computation. By combining the
sensor elements, processing electronics, and firmware in
to a 6.5mm by 6.5mm by 1.5mm LCC package,
Honeywell offers a complete, ready to use electronic
compass. This provides design engineers with the
simplest solution to integrate high volume, cost effective
compasses into wireless phones, consumer electronics,
vehicle compassing, and antenna positioning.
- Simple I2C interface
- 2.7 to 5.2V supply range
- 1 to 20Hz selectable update rate
- True drop-in solution
- 0.5 degree heading resolution
- 1 degree repeatability
- Supply current : 1mA @ 3V
This schematic diagram shows the basic HMC6352 application circuit with a minimum of external components.
Figure 1, the host microprocessor (uP) controls the HMC6352 via I2C
serial data interface lines for data (SDA) and clock (SCL). Two external
10k-ohm pull-up resistors to the nominal +3 volt DC supply create
normally high logic states when the interface lines are not in use. The
host initiates use of the interface by creating the 100kHz clock and
pulling low the data line to indicate the start condition. The data line
logic state transitions are only allowed during the clock low states
and require the data line to be stable in the high states, with the
exception of the start and stop conditions. The 0.01uF supply decoupling
capacitor in this reference can be omitted if another supply filter
capacitor is already included in the overall circuit design. If the
supply traces extend beyond a couple inches to the HMC6352, it is
advisable to add a local supply decoupling capacitor near the HMC6352 to
retain optimum circuit stability.
Additional masters and slaves can
be added to the I2C bus traces without interface trouble to the HMC6352.
There are no periodic maintenance commands required, and even HMC6352
sleep mode or power shutdown can be accomplished without harm to the
data or clock lines.