Data Sheet

MaxBotix

Inc.

Patent 7,679,996

LV-MaxSonar

EZ™

Series

Page 3

Web: www.maxbotix.com

PD11832f

MaxBotix Inc., products are engineered and assembled in the USA.

cancellation of the returning waveform resulting in inaccuracies of up to 2-inches. These effects become less prevalent as

the target distance increases, and has not been observed past 20-inches.

General Power-Up Instruction

Each time the LV-MaxSonar-EZ is powered up, it will calibrate during its first read cycle. The sensor uses this stored

information to range a close object. It is important that objects not be close to the sensor during this calibration cycle. The

best sensitivity is obtained when the detection area is clear for fourteen inches, but good results are common when clear

for at least seven inches. If an object is too close during the calibration cycle, the sensor may ignore objects at that

distance.

The LV-MaxSonar-EZ does not use the calibration data to temperature compensate for range, but instead to compensate

for the sensor ringdown pattern. If the temperature, humidity, or applied voltage changes during operation, the sensor may

require recalibration to reacquire the ringdown pattern. Unless recalibrated, if the temperature increases, the sensor is

more likely to have false close readings. If the temperature decreases, the sensor is more likely to have reduced up close

sensitivity. To recalibrate the LV-MaxSonar-EZ, cycle power, then command a read cycle.

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Timing Diagram

Timing Description

250mS after power-up, the LV-MaxSonar-EZ is ready to accept the RX command. If the RX pin is left open or held high,

the sensor will first run a calibration cycle (49mS), and then it will take a range reading (49mS). After the power up delay,

the first reading will take an additional ~100mS. Subsequent readings will take 49mS. The LV-MaxSonar-EZ checks the

RX pin at the end of every cycle. Range data can be acquired once every 49mS.

Each 49mS period starts by the RX being high or open, after which the LV-MaxSonar-EZ sends the transmit burst, after

which the pulse width pin (PW) is set high. When a target is detected the PW pin is pulled low. The PW pin is high for up

to 37.5mS if no target is detected. The remainder of the 49mS time (less 4.7mS) is spent adjusting the analog voltage to

the correct level. When a long distance is measured immediately after a short distance reading, the analog voltage may not

reach the exact level within one read cycle. During the last 4.7mS, the serial data is sent.