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I have a MaxBotix (MB7092) Ultrasonic sensor. It has an analog pin as well as serial transmission capabilities.

I'll be using the sensor with an Arduino.

Can you tell me the benefits of the digital reading over the analog in the case where the Arduino has ADC capabilities.

Ultimately I'm kind of wondering which way is the lowest power requirement of the overall system (sensor and arduino).

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I would recommend you favour the digital interface over the analogue one.

You do not mention what distance the MB7092 analogue output will be travelling to reach your Arduino but it can pick up noise on the way. Another consideration is that the ADC will have a variety of conversion errors that will bring some inaccuracy into the ADC output.

On a brief examination, I cannot see if the sensor (a) starts with an analogue measurement internally then also converts it to digital with an internal ADC or (b) starts with a digital measurement internally and also converts it to analogue internally using a DAC. I would venture that it probably does (b).

If it is (b), then using the analogue output would mean the MB7092 reading going from its DAC to your ADC, increasing the errors between its internal digital value and yours.

The digital signal is much more resilient to noise so it travels better. It uses two wires (RXD and GND) just like the analogue input would have to. And it may involve fewer DAC/ADC conversions and therefore be more accurate.

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  • \$\begingroup\$ Thanks Tony, do you think the power consumption differences are negligible? I'm looking to make a long-term, compact IoT device, as it will be battery powered. As such, the wiring would be very short, however there would be some RF. \$\endgroup\$ – AJR Jan 14 '17 at 0:03
  • \$\begingroup\$ @AJR, apologies, forgot to answer the power consumption part: yes, I would expect it to be a very small fraction of the sensor's supply current. I did look at this sensor in detail two years ago and concluded that the digital interface was definitely better to me. \$\endgroup\$ – TonyM Jan 14 '17 at 0:30
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Analog or digital makes little difference on power considering 5V operation is 100mA peak per Tx pulse.

The bigger reason is how much resolution, sensitivity and object detection latency is needed.

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