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AM3354: AM3354

jian wang87
Intellectual 370 points
Part Number: AM3354

What's the pin status( high impedance?)  when power up for AM3354BZCZA100? I pull down 10k resistor at pin C16, but there is 0.9V at this pin when power up,  this will make the NPN on when power on. it is so strange. 

is anyone can help?

  • 0
    TI__Guru* 92835 points

    Hello Jian,

    * What software are you using?

    * How are you setting the pinmux settings for that pin?

    * Are you seeing something different from your pinmux settings on the GPIO?

    Regards,

    Nick

  • 0 in reply to Nick Saulnier
    Intellectual 370 points

    HI Nick

    software is IAR.

    when this happen, the initialization is not finished. when finished, the output is OK.

  • 0 in reply to jian wang87
    TI__Guru* 80020 points

    Jian, check the AM335x datasheet https://www.ti.com/lit/gpn/am3354 Table 4-1 for pin C16.  It shows High-z during reset (Ball Reset State) and High-impedance with an active pull up after reset (Ball Reset Rel State).  The internal pull resistor value can vary quite a bit depending on process, but rule of thumb is typically it is around 30K.  You will need a stronger on board pull down to overcome this (<5K), or choose a different GPIO that doesn't have a pull enabled in Reset Rel State.

    Regards,

    James.  

  • 0 in reply to JJD
    Intellectual 370 points

    Got it, thanks

  • 0 in reply to jian wang87
    Expert 2785 points

    Hi,

    I am using gpio2_21 pin as input in my am335x ZCZ package. In hardware i am getting the signal as 1 and 0
    But using with this declaration in my dts and using system calls is getting always 0.

    Please check the below declaration to read the gpio in am335x and suggest me.

    declaration in DTS file:-

    am33xx_pinmux: pinmux@44e10800 {
        pinctrl-names = "default";
        pinctrl-0 = <&mygpio1_pins_default>;
     
        mygpio1_pins_default: mygpio1_pins_default {
            pinctrl-single,pins = <
                0x140 (PIN_INPUT_PULLDOWN | MUX_MODE7) /* (M16) gmii1_rxd0.gpio2[21] */
            >;
        };
    };


    #gpio as Input gpio2_21 = 85
    echo '85' > /sys/class/gpio/export
    echo "in" > /sys/class/gpio/gpio85/direction
    cat /sys/class/gpio/gpio85/value

    please find the below circuit to read the input signal.


    Regards,
    lofna

  • 0 in reply to lofna kumari
    Expert 2785 points

    find the circuit.

    Regards

  • 0 in reply to lofna kumari
    Intellectual 370 points

    Hi

    First make sure the two resistors are solder well. For PIN M16, It shows "L" during reset (Ball Reset State) and "L" with an active pull down after reset (Ball Reset Rel State).  you can try changing 10k to 4.7k. if this doesn't solve this, check your code again.

    regards

    wang jian

  • 0 in reply to jian wang87
    TI__Guru* 80020 points

    What is the connection off the right side of the schematic?

    James