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Thread: T3.6 and T4 Compatibility problem with XPT2046 and Audio Shield

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    T3.6 and T4 Compatibility problem with XPT2046 and Audio Shield

    It appears that T4 has a compatibility problem with the Audio Shield and the XPT2046 library. The library touch screen controller is hardwired to pin 11 for MISO and the audio adapter uses pin 11 for the audio clock. They don't want to play nice together. The library works fine with T3.6 but not with T4. It appears as though Touch Read is always true regardless of whether the screen is touched or not. Is anyone else having this issue and, if so, have you figured out a work-around?

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    Quote Originally Posted by econjack View Post
    It appears that T4 has a compatibility problem with the Audio Shield and the XPT2046 library. The library touch screen controller is hardwired to pin 11 for MISO and the audio adapter uses pin 11 for the audio clock. They don't want to play nice together. The library works fine with T3.6 but not with T4. It appears as though Touch Read is always true regardless of whether the screen is touched or not. Is anyone else having this issue and, if so, have you figured out a work-around?
    Note, pin 11 is MOSI, and pin 12 is MISO by default.

    PJRC just released a revision D of the Audio Shield that works with the Teensy 4.0 (but not the T3.6 without using jumper wires). On the Teensy 4.0, the SPI pins are back to 11-13, and the I2S (sound) pins are 23, 21, 20,7, and 8. So in theory, the T4, the new T4 audio shield, and the XP2046 should all work together without any jumper wires.

    For the T3.6 using the revision A-C shields, you have to use the alternate pins for SPI. I would imagine with the XP2046, you just need to use jumper wires to connect pin 7 on the Teensy 3.6 to the MOSI port on the XP2046. You would need to use the SPI.SetMosi function to change to use the alternate MOSI pin on the T3.6 to support using pin 7 instead.


    Earlier I posted about connecting a Teensy 4.0 to a revision A/B/C Audio board and what jumper wires you need to do. As I said there, it was found that the Teensy 4.0 requires the MCLK signal to have a 100 ohm resistor wired in series (revision C board adds this wire):

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    Quote Originally Posted by MichaelMeissner View Post
    Note, pin 11 is MOSI, and pin 12 is MISO by default.

    PJRC just released a revision D of the Audio Shield that works with the Teensy 4.0 (but not the T3.6 without using jumper wires). On the Teensy 4.0, the SPI pins are back to 11-13, and the I2S (sound) pins are 23, 21, 20,7, and 8. So in theory, the T4, the new T4 audio shield, and the XP2046 should all work together without any jumper wires.

    For the T3.6 using the revision A-C shields, you have to use the alternate pins for SPI. I would imagine with the XP2046, you just need to use jumper wires to connect pin 7 on the Teensy 3.6 to the MOSI port on the XP2046. You would need to use the SPI.SetMosi function to change to use the alternate MOSI pin on the T3.6 to support using pin 7 instead.


    Earlier I posted about connecting a Teensy 4.0 to a revision A/B/C Audio board and what jumper wires you need to do. As I said there, it was found that the Teensy 4.0 requires the MCLK signal to have a 100 ohm resistor wired in series (revision C board adds this wire):
    Thanks, Michael! I did do a search, but did not see these posts. I'll check these out...thanks again!

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