INFICON Spot CDS550D - Manual (Page 13)

Research & Development
SPOT CDS500D & CDS550D OEM Sensor SPI-Interface Specification_V1.1 Page 13 of 14
Christian Berg, T based on Felix Mullis, TL Created 11/10/2014 2:36:00 PM
5.2.5 Single Measurement Cycle
Figure 4: Single measurement cycle
•
Ch 1 (yellow) depicts the signal directly at the sensor
•
Ch 2 (blue) equals the RDY (Ready) signal
As can be seen from Figure 4, a single measurement cycle needs about 300µs. Again, this figure can
vary from sensor to sensor with up to +/-15%. During a single measurement cycle, the electronics
takes 16 single measurements and computes the average of them. Then it signals “new measurement
available” by asserting the Ready-signal low.
5.2.6 Readout Time Window
The “Readout Time Window”-Time is the time span between the negative going edge of the Ready-
signal and the beginning of a new measurement.
With
•
“Readout Time Window”-time = T_rd_out
•
“Total Measurement Cycle”-time = T_tot_cycle
•
“Single Measurement Cycle“-time = T_sgl_cycle
we get
T_rd_out = T_tot_cycle – T_sgl_cycle
For the example above : T_rd_out = 682µs - 300µs = 382µs.