teensy 2.0 and waveshare 4.2in black and white epaper display compatability

[blake]

I recently compiled the demo code for the waveshare 4.2 inch black and white epaper display on an arduino uno and was hoping I could recompile for a teensy 2.0 as well. It seems to compile successfully with 2.0 IDE, but after I upload I do not see anything happening on the screen (as I did with the uno). Is this library compatible?

 

[BriComp]

Forum Rule: Always post complete source code & details to reproduce any issue!

 

[KurtE]

As @BriComp mentioned, it helps people help you if you posted additional information...

Like is it this display? https://www.amazon.com/4-2inch-Module-Communicating-Resolution-Controller/dp/B074NR1SW2 ?

What sketch are you running, with which library...

I would think that it should work, I believe this one uses SPI... But maybe there is something in their library that they have #ifdef specific to UNO... or ???

 

[blake]

Hi all, apologies for the lack of code in my original post.

Yes, it is the above mentioned one from the Amazon link.

Here is the demo code for the arduino uno…

/**
 *  @filename   :   epd4in2-demo.ino
 *  @brief      :   4.2inch e-paper display demo
 *  @author     :   Yehui from Waveshare
 *
 *  Copyright (C) Waveshare     August 4 2017
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documnetation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to  whom the Software is
 * furished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS OR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include <SPI.h>
#include "epd4in2.h"
#include "imagedata.h"
#include "epdpaint.h"

#define COLORED     0
#define UNCOLORED   1

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  Epd epd;

  if (epd.Init() != 0) {
    Serial.print("e-Paper init failed");
    return;
  }
	//Serial.print(UNCOLORED);
  /* This clears the SRAM of the e-paper display */
  epd.ClearFrame();

  /**
    * Due to RAM not enough in Arduino UNO, a frame buffer is not allowed.
    * In this case, a smaller image buffer is allocated and you have to 
    * update a partial display several times.
    * 1 byte = 8 pixels, therefore you have to set 8*N pixels at a time.
    */
  unsigned char image[1500];
  Paint paint(image, 400, 28);    //width should be the multiple of 8 

  paint.Clear(UNCOLORED);
  paint.DrawStringAt(0, 0, "e-Paper Demo", &Font24, COLORED);
  epd.SetPartialWindow(paint.GetImage(), 100, 40, paint.GetWidth(), paint.GetHeight());

  paint.Clear(COLORED);
  paint.DrawStringAt(100, 2, "Hello world", &Font24, UNCOLORED);
  epd.SetPartialWindow(paint.GetImage(), 0, 64, paint.GetWidth(), paint.GetHeight());
  
  paint.SetWidth(64);
  paint.SetHeight(64);

  paint.Clear(UNCOLORED);
  paint.DrawRectangle(0, 0, 40, 50, COLORED);
  paint.DrawLine(0, 0, 40, 50, COLORED);
  paint.DrawLine(40, 0, 0, 50, COLORED);
  epd.SetPartialWindow(paint.GetImage(), 72, 120, paint.GetWidth(), paint.GetHeight());
  
  paint.Clear(UNCOLORED);
  paint.DrawCircle(32, 32, 30, COLORED);
  epd.SetPartialWindow(paint.GetImage(), 200, 120, paint.GetWidth(), paint.GetHeight());

  paint.Clear(UNCOLORED);
  paint.DrawFilledRectangle(0, 0, 40, 50, COLORED);
  epd.SetPartialWindow(paint.GetImage(), 72, 200, paint.GetWidth(), paint.GetHeight());

  paint.Clear(UNCOLORED);
  paint.DrawFilledCircle(32, 32, 30, COLORED);
  epd.SetPartialWindow(paint.GetImage(), 200, 200, paint.GetWidth(), paint.GetHeight());

  /* This displays the data from the SRAM in e-Paper module */
  epd.DisplayFrame();

  /* This displays an image */
  //epd.DisplayFrame(IMAGE_BUTTERFLY);

  
  
  epd.Init_4Gray();
  epd.ClearFrame();
  epd.Set_4GrayDisplay(gImage_4in2_4Gray1, 100, 100,  200,150);

  /* Deep sleep */
  epd.Sleep();
}

void loop() {
  // put your main code here, to run repeatedly:

}

This program comes with a handful of .h and .cpp files as well.

 

[KurtE]

Sorry I don't see anything obvious in the files you posted. I don't have one of these displays so can not debug it. Maybe someone who uses them???

 

[blake]

Yes this is the wall I hit as well :-/

 

[KurtE]

Sorry I don't use Teensy 2 boards, so decided to take a quick look again

And I noticed that the SPI pins are not on the pins you are mentioning.

It is on Arduino pins 0-3...

 

[blake]

I saw that as well, but when I originally compiled it for the Uno and used the pins specified by Waveshare, it compiled and ran correctly.

 

[KurtE]

Yes the UNO has a different pinout than the T2.0 What the code is talking to, is the SPI interface not the MISO, MOSI, SCK pins. The SPI code does that.

From cores\teensy\core_pins.h in the Teeny 2.0 section.

#define PIN_B0		0
#define PIN_B1		1
#define PIN_B2		2
#define PIN_B3		3
...
#define CORE_SS0_PIN            PIN_B0
#define CORE_MOSI0_PIN          PIN_B2
#define CORE_MISO0_PIN          PIN_B3
#define CORE_SCLK0_PIN          PIN_B1

Which confirms the card image I showed in previous post.

So you need to move your connections to the Teensy 2 pin numbering.
Also you may need to experiment on which pins to use for CS and DC. Yours are probably fine, unless you are using those pins for something else.

 

[blake]

Thank you for help!

I believe I am confused regarding the pin labeling for the SPI communication vs the labeling for the 8 pin header connected to the epaper display.

From epdif.h for the Uno

// Pin definition
#define RST_PIN         8
#define DC_PIN          9
#define CS_PIN          10
#define BUSY_PIN        7

 

[blake]

Success.

I "crosspatched" DIN (aka MOSI), CLK (aka SCK), CS (aka SS) from the arduino pins of 11,13, and 10 to the teensy 2.0 pins of 2, 1, and 0. In addition, I edited the line from epdif.h from

#define CS_PIN          10

to

#define CS_PIN          0  // SPI chip select pin for teensy 2.0

Thanks again for your assistance.

 

[KurtE]

I am glad you have it working and you are welcome.