NHD-1.5-128128ASC3 and Teensy 3.6



  • killkrt
    Some updates,

    I have change my wiring in this way:

    • Pin 0 -> GND
    • Pin Vin -> VDD
    • Pin 15 -> D/C
    • Pin 14 -> RES
    • Pin 13 -> SCK
    • Pin 10 -> See later
    • Pin 11 -> MOSI

    I was connecting Pin 10 to OLEDCS, but I realized (by mistake) that if I leave it disconnect at startup and then (after 3 seconds) I connect to SDCS everything works!  
    Anyway this is an awful workaround since I have to manually disconnect pin 10 every time that I startup my Teensy and then connect it to SDCS (instead of OLEDCS).

    Do you have an idea why this is happening?

    Thank you
  • Ted M.
    NHD Staff
    Hi Killkrt,

    Both Chip Select signals for the OLED (OLEDCD) and the SD card reader (SDCS) are active low and would need to be active independently of each other. 
    Using a pull-up resistor on each of these Chip Select lines will ensure they are both inactive on power up.

    Best Regards,
  • killkrt

    Thank you for the hints.

    I put two pull-up resistors as you suggested, but I still have problems.
    The SDCS is connected to a pin that it is always high, while the OLEDCS is connected to pin 10 (that is the SPI CS).

    I dump the two CS during restart with my oscilloscope, as you can see they seem to be stable high while it is rebooting.
    Yellow: Pin 10 connected to OLEDCS
    Purple: Pin 30 always high connected to SDCS

  • killkrt

    I got it working using two pull-down resistors (instead of pull-up) on OLEDCS and SDCS.
    OLEDCS is connected to a pin always set to 0.
    SDCS is connected to my CS.

    In some way it seems that it's working in reverse, using a pull-down instead of pull-up, and using SDCS instead of OLEDCS   

    So this is my wiring:

    « Last Edit: November 02, 2018, 07:46:49 AM by killkrt »
  • Ted M.
    NHD Staff
    Its good to see you have this working.  In some cases the logic low does not get pulled down strong enough and requires a pull down resistor.

    Thanks for providing your feedback on this.

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