Source
The source signal for Alarm Mode can be chosen from 4 points which the microcontroller has
access to. These are four internal points input amplifier out (IAO), gain amplifier out (GNO),
temperature amplifier out (TPO), and voltage mode output (VMO).
3.4) Temperature & Signal Data
The temperature and signal data is displayed for use by the user in determining the temperature
and linearization coefficients.
Update
The Update button is used to request the Temperature (Temp) and Signal data be updated. The
software reads the appropriate RAM locations and displays the data when this button is used.
Whenever the temp or signal data is needed, the displayed data has to be updated.
Temp Value
The temperature value is displayed from RAM locations 58 and 59. The data is 10 bits and is
right justified in the 16 bit field. The software shifts the data left before being displayed by the
software (divided by 64). The data is only updated when the update button is pressed.
Signal In Value
The digitized value of the sensor’s signal is displayed from RAM locations 46 and 47. While in
Analog Mode, this value is the digitized GNO (gain amplifier output) and is proportional to the
output. In Digital Mode, this data is the 'signal in value' (RAM locations 46 and 47) or the
'signal out value' (RAM locations 60 and 61). These are, respectively, the signal values before
and after the linearization calculation. Setting the PC values to +1.0 (1024 decimal) means that
the 'signal in value' = 'signal out value'. (Both ADC and DAC are 10 bits). The data is only
updated when the update button is pressed.
3.5) Temperature Compensation
The MLX90308’s temperature compensation algorithm is piece-wise with up to 4 temperature
segments, see figure 9. Within each temperature segment (‘gap’), the correction is a first order
calculation. There are separate temperature coefficients for gain and offset.
MLX90308CCC & MLX90314AB Software Users Manual
Rev 2.0
14
11/28/01