MLX75031 Datasheet, PDF (32/67 Pages) Melexis Microelectronic Systems – Optical Gesture & Proximity Sensing IC

MLX75031
Optical Gesture & Proximity Sensing IC
with Integrated LED Drivers
Datasheet
8.11.4. SM – Start Measurement
The SM command is used to start up measurement cycles.
Two different Measurement Sequences can be selected with option bit M₆:
• setting M₆ high enables the Measurement Sequence 1, wherein the two Ambient Light Channels,
the die temperature and the voltage on the VSUP pin are measured
• setting M₆ low enables the Measurement Sequence 2, wherein the DC Light, the Active Light, the
LED Temperature and the voltage on the VSUP pin during the Active Light pulse are measured.
When M₆ is set low, 4 other option bits are available in order to select the LED that needs to be
fired and to select the Active Light channel that needs to be read out:
- M₃: setting this bit high fires LED A and measures the temperature of LED A
- M₂: setting this bit high fires LED B and measures the temperature of LED B
- M₁: setting this bit high enables the Active Light measurement in channel A
- M₀: setting this bit high enables the Active Light measurement in channel B
The table below gives the overview of available options bits in the SM command.
Control2 Bits
M6
M5
M4
M3
M2
M1
M0
Available
Measurements
Measurement Sequence 1
Measurement Sequence 2
Set to 1
Set to 0
Set to 0
Set to 0
Set to 0
Set to 0
Set to 0
1 = Fire + Measure Temperature of LED A
0 = Don't fire + Measure Temperature of LED A
Set to 0
1 = Fire + Measure Temperature of LED B
0 = Don't fire + Measure Temperature of LED B
Set to 0
1 = Measure Active Light on Channel A
0 = Don’t measure Active Light on Channel A
Set to 0
1 = Measure Active Light on Channel B
0 = Don’t measure Active Light on Channel B
Die temperature
DC light before Active Light pulse
Ambient light channel C
Battery voltage during Active Light pulse
Ambient light channel D
Active Light measurements
Battery voltage
Temperature of LED
Table 15 : Available option bits in SM Command
A typical timing diagram is given in Figure 11. After uploading the SM command, the measurement cycle is
started as soon as the CS pin is set high. The ADC starts converting all the needed analog voltages and stores
the digital values in registers.
A time t_{cs_dr} after CS is set high, the state of the DR pin goes low. A time t_dr after DR was set low, the state of
the DR pin becomes high, indicating that all measurements are completed and that the resulted data is
available for read-out (read-back of the stored data in the registers). This time can be up to 239us, if an
internal auto-zeroing process is under execution and needs to be finished.
REVISION 001 – JANUARY, 2013
39010xxxxx
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