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uLCD-24PTU - Low battery detection

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  • uLCD-24PTU - Low battery detection


    I try to check LiPo battery level.
    As said in uLCD-24PTU Datasheet Rev1.8, I try to pool IO2_PIN but it always reads '0' even when battery level is about 3.6v.
    when charging IO2 also read '0'.

    my display is HW REV 12.01

    I read that normally default function for IO2_PIN is battery level control, but I saw it can be changed by solder jumper SB3

    so where are jumper SB1, SB2, SB3 ? I can't see them on the display module

    How can I make battery checking works ?

    My test code is simple:

    pin_Set(IO2_PIN,INPUT); // normally default after power-on reset
    print(pin_Read(IO2_PIN)); // always reads 0

    Thanks for answers

  • #2
    Hello B2V,

    Solder Bridges SB1, SB2 and SB3 did not come in until HW REV 13.0
    So this is not a feature of your module. Please refer to the Hardware Change Log at the back of the Datasheet.

    On revision 12.1, IO2 is connected to STAT (the signal from the battery checking circuit) by default, via resistor R8 (instead of SB3 on newer boards).
    If your battery voltage is higher, does IO2 change at all?

    The STAT pin is a very basic battery check, it does not give you a level.



    • #3
      Thanks James for HW 13.0

      unfortunatly it still reads '0' with a fully charged battery (4.1v alone and 4.2v charging between pins +ve & -ve)

      Last edited by B2V; 1st March 2017, 05:55 AM.


      • #4
        Oki It works properly but...

        Instead of "when the Lithium battery has reached a low level (3.7V)"
        We must read (far below 3.7V)..........

        I've just have my display module connected to an adjustable supply.
        IO2_PIN toggle to '1' below 3.3v (at this voltage, display still works with lower backlights ^^)

        May be the documentation has to be adjusted or my display module is specifically low in battery level check
        thanks for all