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Battery voltage indicator question

Posted by Ben on May 31, 2010 at 12:05am
I'm using Ardupilot with V2 shield. Power to the board is by ESC, not by battery. The configuration on the Ardupilot board is thus the "default" PSEL option. I followed the manual and soldered a wire to the indicated jumper to measure the voltage of another battery (that is not powering the Ardupilot). I also changed the header file to indicate a battery event. However, I am not getting any battery voltage reading from the ArduStation GCS application.

Have a few questions. Does the voltage monitoring pin (A5) have to be used in conjunction with PSEL = battery? If i power the Ardupilot board via ESC (default option), can I still use A5 to monitor some battery voltage?

I have tried switching the PSEL to battery instead of servo, but still unable to get any reading on the GCS. What is the voltage range of the input pin A5? Does it have circuitry to scale it down to 5V level if the battery is say 15V? Is it possible to take in voltage of 24V and more?

Appreciate any advice. Thanks!

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Replies

  • Moderator
    Nathaniel Caner May 31, 2010 at 2:30pm
    Ben,

    Check out this post I just made. I think it will help explain things. Check the attached schematic of the shield to see the circuit for the voltage divider in the upper left corner R9 and R8 are the controlling resistors.

    Ardupilot_shield_v21_sch.pdf')Ardupilot_shield_v21_sch.pdf

    Ardupilot_shield_v21_brd.pdf')Ardupilot_shield_v21_brd.pdf

  • Ben May 31, 2010 at 2:44am
    Something weird happened. The Ardupilot board suddenly switched to baud rate 115200 from the original 57600 (i'm using EM406). What is the cause of this? How do i switch it back to 57600?
  • Ben May 31, 2010 at 1:32am
    Hi, just thought I would post an update. There was no battery reading previously because there was no GPS lock. It is now printing out some value.

    Some questions remain:

    1) Apparently, I can use PSEL = servo and monitor the voltage level of the receiver by connecting the pin (A5) as per the manual instructions to the positive terminal of the output pins. Am I correct to say that?

    2) Based on the above setup, can I still feed in an analog voltage from another battery to pin A5 to monitor the battery level, assuming that the ESC and the battery has common GND? What is the maximum voltage it can take? What is the role of the #define INPUT_VOLTAGE in the header file? If for example, my other battery (not the ESC) is a 12V battery, do I change the #define INPUT_VOLTAGE to 12000.0?

    Appreciate any help! Thanks in advance!
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