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BOOSTXL-PGA460: connecting MB1200: XL-MaxSonar-EZ0 sensor to the BoostXL GUI

Paul Wiesbrock
Prodigy 50 points
Part Number: BOOSTXL-PGA460
Other Parts Discussed in Thread: PGA460, , PGA460-Q1

I am at the moment testing a few diffrent ultrasonic sensors with the boost xl gui and it is working avas intended with the transducers i have tested so far.

But now i would also try to run a few tests and monitor the activity with a maxbotix sensor that comes with its own PCB.
namely talking abot this one https://www.maxbotix.com/Ultrasonic_Sensors/MB1200.htm .
is it even possible to set it up with the boostxl pga460 gui?
thanks in advance.

  • 0
    TI__Mastermind 27950 points
    Hi Paul,

    Yes, it is possible to remove/isolate the 42kHz MB1200 transducer from the MB1200 XL-MaxSonar-EZ0 module, and use it on the PGA460-Q1 EVM. Because this transducer is an open-top, it likely does not require a large driving voltage, and you should be able to connect the transducer to the direct-drive section of the BOOSTXL-PGA460 daughtercard. For details on the hardware modifications to use a different transducer with the EVM, refer to the PGA460 FAQ ( www.ti.com/.../slaa733.pdf ):
    • 4.4.1 How do I use a different transducer on the transformer driven circuit?
    • 4.4.2 How do I use a different transducer on the direct driven circuit?
  • 0 in reply to Akeem Whitehead
    Prodigy 50 points
    thank you for your reply akeem,

    i have a couple more questions for you though.
    would i have to desolder the maxbotix transducer in order to do that?
    is there a way to just use the pins on the maxbotix pcb and use the BosstXl PGA460-Q1 Evaluation GUI to monitor the Echo Signals of the Maxbotix Sensor?

    the guys over at maxbotix dont hand out their schematics so easily so i cant really see if there is a way to access the transducer only, using the provided input and output options. my guess is that all the signals that you can get from the output pins that are on the sensors pcb have ran through the boards own signal processing paths making it impossible to use the PGA460 Evaluation Module on it without desoldering the Transducer first. am i right with this?

    also, how do i determine the actual driving voltage that is supplied to the transducers that i am using?
    the GUI lets me chosse the Driving current, do i have to know my transducers resistance value and calculate the voltage using the current and resistance numbers?

    thank you for taking your time to reply,

    p.wiesbrock
  • 0 in reply to Paul Wiesbrock
    TI__Mastermind 27950 points
    Hi Paul,

    You will have to desolder the transducer on the Maxbotix module. The Maxbotix MB1200 is its own ultrasonic signal conditioner solution (one of our competitors). Essentially, their module solution is the equivalent of our ultras small form factor board (PGA460 Mono-static Transducer Transformer Driver Ultra-Small Design File at www.ti.com/.../slac757 ). There is no way to bypass their driver/receiver circuit without desoldering their transducer.

    The problem is that Maxbotix does not disclose the part number of their transducer. I would only recommend you continue this approach if Maxbotix is willing to tell your the transducer part number, or sell you the transducer only. If you'd like to see a complete listing of off-the-shelf transducer part numbers that are compatible with the PGA460, see the following link ( Air-Coupled Ultrasonic Transducers & Transformers Listing for PGA460: e2e.ti.com/.../620399 )

    I can't comment on how Maxbotix determines the transducer excitation voltage, but the PGA460 is based on the following:
    • Center-tap voltage to transducer.
    • Driver current limit of 50-500mA.
    • Transformer's turns ratio.
    You need to know your transducer's maximum drive voltage rating. Most closed-top transducers are rated for 100~200Vpp, while most open-top transducers are rated up to 40~50Vpp.

    You can look at the driver current limit as your peak-to-peak (volume) knob for driver voltage. Thus, if you want to get the maximum excitation voltage at the secondary, you set the driver current to 500mA. In a system with a typical center-tap transformer with a turns-ratio of 1:1:8, and a center-tap voltage of 8V, you should expect to see a voltage of 128Vpp (+/- 64V). Let's say your transducer is only rated for 80Vpp. With the same center-tap voltage, you can reduce the driver current limit to 200mA for example to generate a secondary voltage of ~80Vpp. Refer to the PGA460 Ultrasonic Module Hardware and Software Optimization appnote section 4.3 Current Limit to see how your peak drive strength is impacted. You'll notice increasing from 50-500mA is not linear; instead, it is more logarithmic, where the initial change in peak-to-peak is significant (50~200mA), but eventually saturates near the larger current limit (400~500mA). You'll need to experiment with the driver current limit to find the optimal setting based on your center-tap voltage and pulse count.
  • 0 in reply to Akeem Whitehead
    Prodigy 50 points
    Thank you very much for this reply Akeem.
    I could not have asked for more.