I am having a serious issue here. I've bought a Maxbotix XL ultrasonic sensor but I didn't know that it is the AE version, that does not come with pulse width, it comes with Analog Envelope. I have a 8051 board and I need to read these Analog envelope data and measure the distance. I don't know what analog envelope is, but I also have a common analog output, how can I read this data from 8051?

I am very grateful


1 Answer 1


You don't mention the specific part number that you have; I looked at the datasheet for the MB1310, which is an AE part in the XL series. The last page of the datasheet shows sample waveforms for the "Analog Envelope" output - it is essentially the unfiltered output of the range sensor. This would be useful if you want to process multiple return signals, at the expense of extra code complexity.

Here are the datasheet waveforms:

Analog Envelope

For your application, you may want to use the AN output, which is a voltage output that is ratiometric with distance. Note that you'll need an extra analog input on your 8051 board to do this.

From the datasheet:

Pin 3 - (AN) This pin outputs analog voltage with a scaling factor of (Vcc/1024) per cm. A supply of 5V yields ~4.9mV/cm., and 3.3V yields ~3.2mV/cm. Hardware limits the maximum reported range on this output to ~700 cm at 5V and ~600 cm at 3.3V. The output is buffered and corresponds to the most recent range data.

  • \$\begingroup\$ Your answer turned up first, so instead of adding the same answer I took the liberty of putting the clip (it is for the MB1300 but there is no difference to the function of the pin) I took into your answer, hope you don't mind. \$\endgroup\$
    – Oli Glaser
    Sep 29, 2012 at 18:37
  • \$\begingroup\$ @Oli, I don't mind at all. Your answers set a pleasantly high standard, and I could benefit from your "picture worth a thousand words" approach. \$\endgroup\$
    – HikeOnPast
    Sep 29, 2012 at 18:43
  • \$\begingroup\$ Thanks for the answer! How can I add an extra analog input on my board? \$\endgroup\$ Sep 29, 2012 at 19:03
  • \$\begingroup\$ @ViniciusTavares: What board do you have, exactly? \$\endgroup\$
    – Dave Tweed
    Sep 29, 2012 at 19:13
  • \$\begingroup\$ I have an AT89S52 microprocessor, the board is a custom one and not developed by me, by the way, I have its electrical scheme: i.imm.io/G59P.jpeg \$\endgroup\$ Sep 29, 2012 at 19:32

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