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Thread: 8 x 1.44/1.8'' inch 128x128 128x160 TFT Full Color SPI LCD Display Modules over SPI

  1. #26
    Senior Member+ KurtE's Avatar
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    Jan 2014
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    With T4 - only Pin 10 is CS pin on that SPI buss - And it works very differently than T3.x

    That is with T4 you con't have the PUSHR register where you can select which if any (may be more than one) are to be asserted during that SPI transfer, and the CONT bit will say if those assertions should continue after that transfer completes.

    Instead with the T4 you do have a FIFO queue, and you have two different registers that can be put onto the queues:
    The standard: TDR which you can transfer up to 32 bits of data
    And the TCR (Transfer control register) which you can adjust things like word size... With this you can choose which CS channel to assert (only one), and the T4 only has one that was routed out to external IO pin... So very different. With T4 in for example my ili9341_t3n library I got a very slight speedup by using DC on pin 10... But just slight.

  2. #27
    I was able to get six displays running off of a Teensy 3.2. I had to use the updated library from https://github.com/PaulStoffregen/ST7735_t3 dated July 7, 2019.
    I used SCK on 14, MOSI on 11, DC on 21. I used CS on 10, 9, 15, 20 (normal CS pins) plus pins 3 and 4.
    I had to change the SPI clock down to 4 MHz to get it to work, but that's probably because of my long test jumpers.

    Click image for larger version. 

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    I'm building a "nearly NIMO" clock from https://www.hackster.io/paul-bricmon...o-clock-9309ec but I'm using a teensy 3.2 instead of a metro M4 + pro mini.
    I'm using the teensy's RTC instead of a separate module. I use a 1 F capacitor connected to the teensy's VBat pin, charged through a schottky diode tied to the teensy's 3.3v out.
    I set the time via a GPS module connected to Serial1. I also use a Bluetooth module tied to Serial3 to set the timezone and other options.

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