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mLCD-32PTU pin_Set(INPUT,IO3_PIN)

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  • mLCD-32PTU pin_Set(INPUT,IO3_PIN)

    I have connected IO3 pin via resistor ( 100k) to GND. If port IO3 is set as OUTPUT and set pin_HI(IO3) or pin_LO(IO3) I got 3,3v or 0V. But, after that command ( pin_Set(INPUT,IO3_PIN) ) that port is set 3,3V and pin_Read(IO3) is always 1. ? WHY?

  • #2
    Referring to the Datasheet of uLCD-32PTU(page 7), IO3 is excluded from the GPIO pins because IO3 is Peripheral Supply Pin. IO3 has a predefined function as stated in the datasheet. Although it is stated in Page 8 that to set IO3 as INPUT, it needs to use an external circuit to drive this pin.

    IO3 is HIGH all the time because you will see there is a Pull Up(Page 18). This is so by default the Peripheral Supply is ON. So the 47K pull up is beating the 100K pulldown.

    You can refer to this data sheet http://www.4dsystems.com.au/productp...heet_R_1_9.pdf

    And also this forum post for IO3's behaviour http://forum.4dsystems.com.au/forum/..._pin-behaviour
    Symon

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