HAL 1820 DATA SHEET
8 July 3, 2013; DSH000158_003EN Micronas
2.2. Digital Signal Processing and EEPROM
The DSP is the major part of this sensor and performs
the signal conditioning. The parameters for the DSP
are stored in the EEPROM registers. The details are
shown in Fig. 2–2.
The measurement data can be readout from the
DIGITAL OUTPUT register.
DIGITAL OUTPUT
This 16-bit register delivers the actual digital value of
the applied magnetic field after the signal processing.
This register can only be read out, and it is the basis
for the calibration procedure of the sensor in the sys-
tem environment. Only 10 bits of the register contain
valid data. The DIGITAL OUTPUT range is from 512
to 511.
For Sensitivity = 1 the DIGITAL OUTPUT value will
increase for negative magnetic fields (north pole) on
the branded side of the package (positive DIGITAL
OUTPUT values).
Note: During application design, it should be taken
into consideration that DIGITAL OUTPUT
should not saturate in the operational range of
the specific application.
The area in the EEPROM accessible for the customer
consists of four so called customer registers with a size
of 16 bit each.
2.2.1. Customer Register I
Customer register I contains the bits for magnetic sen-
sitivity (SENSITIVITY) and magnetic offset (OFFSET).
SENSITIVITY
The SENSITIVITY bits define the parameter for the
multiplier in the DSP. The Sensitivity is programmable
between 2 and 2. The SENSITIVITY bits can be
changed in steps of 0.0156. Sensitivity = 1 (@ Offset =
0) corresponds to full-scale of the output signal if the
A/D-converter value has reached the full-scale value.
OFFSET
The OFFSET bits define the parameter for the adder in
the DSP. Offset defines the output signal without exter-
nal magnetic field (B = 0 mT).
The customer can decide if the Offset is MSB aligned
or LSB aligned. The MSB or LSB alignment is enabled
by an additional Offset alignment bit (OALN). In case
the OALN bit is 1 the Offset is programmable from
50% up to 50% of V
DD
. This means that the Offset
covers the full-scale range. If the OALN bit is set to
zero, then the Offset covers only 1/4 of the full-scale
(12.5% up to 12.5% of V
DD
). The customer can
adjust the Offset symmetrically around 50% of V
DD
(37.5%... 62.5% of V
DD
). The OFFSET register can be
set with 8-bit resolution.
2.2.2. Customer Register II
Customer register II contains the bits for magnetic
range (MRANGE), linear and quadratic temperature
coefficients (TC and TCSQ), magnetic offset alignment
(OALN) and the customer lock bit.
MRANGE
The MRANGE bits define the magnetic field range of
the A/D converter. The following eight magnetic ranges
are available.
Table 2–2: MRANGE bit definition
Magnetic Field Range BIT SETTING
20 mT...20 mT 0
40 mT...40 mT 1
60 mT...60 mT 2
80 mT...80 mT 3
100 mT...100 mT 4
120 mT...120 mT 5
140 mT...140 mT 6
160 mT...160 mT 7
