Dual Ultrasonic Sensors not responding

Discussion in 'The Projects Forum' started by bumclouds, Feb 27, 2011.

  1. bumclouds

    Thread Starter Active Member

    May 18, 2008
    82
    0
    Hey guys,

    I have a project I'm working on by myself, which is a small robot which drives around and avoids objects using IR sensors and Dual Ultrasonic Sensors.

    I have a network of 3 Dual Ultrasonic Sensor units which are daisy chained together using RS485. RS485 utilizes RS232 protocol, am I right?

    Anyway, I manually address each of the units using my microcontroller to say 0x11, 0x12 and 0x13, for example. When the units are connected to the microcontroller individually (not networked), they behave well.

    When I daisy chain two together, they are also fine... But when I connect 3, the third always works intermittently or just dropps out completely returning a packet of straight zeros every time.

    Could you guys give me some troubleshooting advice?

    Thankyou muchly.

    Andrew
     
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    We need a schematic with part numbers.

    hgmjr
     
  3. bumclouds

    Thread Starter Active Member

    May 18, 2008
    82
    0
    All I have is this datasheet:

    It doesn't have a schematic, unfortunately.
     
  4. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,779
    932
    I think he means a drawing of how these sensors are wired into the microcontroller, and all the supporting components.

    Did you just wire it up a little at a time and NOT use or have any schematics to follow?
     
  5. bumclouds

    Thread Starter Active Member

    May 18, 2008
    82
    0
    Umm.. Not really.. Sorry!!

    It just goes like this:

    Sensor1 --> Sensor2 --> Sensor3 --> Arduino (using ATMega328P + expansion board)

    I plug the output of Sensor 1 into the input of Sensor 2, etc. There is no circuitry made by me.
     
  6. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    It would still be better if you could supply us with a diagram. A picture being worth a thousand words was never truer than in electronics.

    hgmjr
     
  7. bumclouds

    Thread Starter Active Member

    May 18, 2008
    82
    0
    Wait for a little bit and I'll put my photoshop skills to the test =) I'll post again soon.
     
  8. bumclouds

    Thread Starter Active Member

    May 18, 2008
    82
    0
  9. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    Wiring between the Arduino RS-485 shield and the networked ultrasonic sensors must be correct for this to work.

    You will need to provide us with a detailed wiring diagram of your connection for us to help you out.

    Also it would be helpful if you give us the part number of the Arduino RS-485 shield you are using.

    Eventually we will need to see your Arduino program to make sure that you are conforming to the communication protocol outlined in the datasheet for the ultrasonic detectors.

    hgmjr
     
  10. bertus

    Administrator

    Apr 5, 2008
    15,646
    2,345
    Hello,

    Do you also have the jumpers set as stated in the manual?

    Bertus
     
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