TDC1011_15 Datasheet, PDF (23/49 Pages) Texas Instruments – TDC1011 Single Channel Ultrasonic Sensing Analog Front End (AFE) for Level Sensing,Concentration Sensing Applications

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Device Function Description (continued)
Zero-crossing detected after
threshold exceeded
COMPIN
TDC1011
SNAS662 – JULY 2015
V_COM
ECHO_QUAL_THLD
Threshold
Signal exceeds threshold
Output on
STOP pin
Maximum number of requested events (5 in this figure)
returned; subsequent events not reported
Figure 33. Single Echo Receive Mode (5 STOP Events)
If the number of expected pulses programmed in NUM_RX is not received or the time-of-flight operation times
out, the TDC1011 will indicate an error condition in the ERROR_FLAGS register and will set the ERRB pin low.
8.4.4.2 Multiple Echo Receive Mode
The Multiple Echo mode is intended for use in level sensing applications and distance/displacement
measurements in which multiple echoes (burst) are received. In this condition, each received echo group will be
treated as a single pulse on the STOP pin. Up to 7 STOP pulses can be generated based on the value of the
NUM_RX field in the CONFIG_1 register. Multi echo mode can be enabled by setting the RECEIVE_MODE bit to
1 in the CONFIG_4 register. A representation of multiple echo STOP pulse generation is shown in Figure 34.
COMPIN
VCOM
Programmed
threshold
Output on
STOP pin
No pulse on STOP
pin because signal did not
exceed threshold
No pulse on STOP pin because
maximum number of programmed events
(5 in this example) already produced.
Figure 34. Multiple Echo Receive Mode (5 STOP Events)
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