MLX90314
Programmable Sensor Interface
Communications
Level Steering
The MLX90314 firmware transfers a complete byte of
data into and from the memory based on a simple
command structure. The commands allow data to be
read and written to and from the EEPROM and read
from the RAM. RAM data that can be read includes
the current digitized temperature and digitized GNO.
The commands are described below. Melexis provides
setup software for programming the MLX90314.
The level steering option allows configuration of the IO
pins as outputs to indicate the relative level of a
selected signal. See Figure 7. The levels at which the
two outputs change state are programmed by the
user. The programmed levels are set as eight bit
numbers and compared to the upper eight bits of the
digitized signal. This function utilizes the same
resources as the alarm function. The two functions
(level steering and alarm) can not be used
simultaneously. Four bytes in the EEPROM command
this option. The first byte is used to select the input,
while the last three comprise the transition levels. The
control byte for the level steering is the same as for
the alarm. The four MSB’s hold the code for the
selected input. The control byte has several
possibilities as designated by the MUX settings (See
Table 8)
Table 8. Level Steering Bit Definitions
Selected input
TPO
MUX Value
0010
IAO
0110
GNO
VMO
0000
0011
Table 9. Mode Byte Bit Definition
Bit
Function
Remarks
EEPROM Checksum test. Checksum test failure will
7
1= EEPROM Checksum test active
0= EEPROM Checksum test inactive force the output to the value programmed in bytes 40
and 41 of the EEPROM (See Table 10).
6
5
0 = Analog Mode
1 = Digital Mode
Digital mode must be activated when VMO and CMO
both active.
0 = Alarm function inactive
1 = Alarm function active
Alarm functions are like “limiting functions”:
If defined ADC INPUT is below low alarm trigger,
then DIGMOD becomes active with alarm low
output).
If defined ADC INPUT is above high alarm trigger,
then DIGMOD becomes active with alarm high
output.
Note: Deactivated if the level steering mode is active
4
0 = IO1/IO2 are not active outputs
1 = level steering: IO1/IO2 are active
outputs
Depending on the sampled input, IO1/IO2 will be a
two bit digital output. If IO1/IO2 are not active outputs,
then they will be analog inputs.
3
2
1
0 = Turbo inactive
1 = Turbo active
0 = VMO inactive
1 = VMO active
0 = Internal temperature sensor active
1 = External temperature sensor
active
0
0 = CMO inactive
1 = CMO active
CMO has fixed digital value (EEPROM byte - see
below) if both VMO and CMO are active. To activate
this value, the digital mode must be activated.
3901090314
Page 14
Nov/04
Rev 007
MELEXIS [ Melexis Microelectronic Systems ]
