Data Sheet

Timing in Particle-Sensing Mode Using 2 LEDs
The internal FIFO stores up to 32 samples, so that the
system processor does not need to read the data after
every sample (Figure 4).
Figure 4. Timing for Data Acquisition and Communication When in Particle-Sensing Mode Using 2 LEDs
Table 15. Events Sequence for Figure 4 in Particle-Sensing Mode Using 2 LEDs
EVENT DESCRIPTION COMMENTS
1
Enter into Particle-Sensing Mode. Initiate
a Temperature measurement.
I
2
C Write Command sets MODE[2:0] = 0x03. At the same time, set the
TEMP_EN bit to initiate a single temperature measurement. Mask the
DATA_RDY Interrupt.
2
Temperature Measurement Complete,
Interrupt Generated
TEMP_RDY interrupt triggers, alerting the central processor to read the
data.
3 Temp Data is Read, Interrupt Cleared
4 FIFO is Almost Full, Interrupt Generated Interrupt is generated when the FIFO almost full threshold is reached.
5 FIFO Data is Read, Interrupt Cleared
6 Next Sample is Stored
New Sample is stored at the new read pointer location. Effectively, it is
now the rst sample in the FIFO.
INT
I
2
C BUS
LED
OUTPUTS
~
~
~
SAMPLE #1 SAMPLE #2 SAMPLE #3 SAMPLE #16 SAMPLE #17
1 4 5 6
TEMP
SENSOR
TEMPERATURE SAMPLE
2 3
29ms
15ms TO 300ms
IRRED IRRED IRRED IRRED IRRED IRRED IRRED
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MAX30105 High-Sensitivity Optical Sensor
for Smoke Detection Applications