RA8875 Based Display Controller

This page shows a simple demo program for a graphics library supporting a low cost display from buydisplay.com. While the module can be configured for support via I2C, 3-Wire SPI, 4-Wire SPI, 8-bit Parallel or 16-bit Parallel, the companion library only supports the 4-Wire SPI.

You can also find this display on the Components | RA8875 page.

Library

RA8875 Library

Display Pictures

While this image is sharp, the camera/lighting washed out the colors somewhat. /media/uploads/WiredHome/ra8875display.640x380.png

With careful study of the image below, you can see a number of solder-blob jumpers. These jumpers are described quite well in the manual, and configure the many different options. The specific unit shown here is the "entry point" model, it does not have touchscreen, SD card, extra Font memory, or the key pad interface. As you see in the top left, it is wired with an 8-signal ribbon cable (but note in the schematic that it only needs 6 as the two power and two ground are internally connected together in the module).

/media/uploads/WiredHome/ra8875displaymodulerr.jpg

Also note, that some configuration changes go beyond the jumpers. I decided to switch my configuration to 4-Wire SPI and had to remove R1, R2, and R3 (which were zero-ohm that shorted the SPI input pins to +v!). I also changed some of the solder-blob jumpers, but that was easy. Had I ordered the display with the support for 4-Wire SPI, that would not have been necessary.

Schematic

The library should be able to work with any SPI port, and the Chip Select pin is a simple DigitalOut pin, chosen from the unused pins on my baseboard.

/media/uploads/WiredHome/ra8875_display_schematic.png

Sample Program

#include "mbed.h"
#include "RA8875.h"

Serial pc(USBTX, USBRX);

int main()
{
    pc.baud(460800);    // I like a snappy terminal, so crank it up!
    pc.printf("\r\nRA8875 Test - Build " __DATE__ " " __TIME__ "\r\n");

    RA8875 lcd(p5, p6, p7, p12, NC, "tft");    // MOSI, MISO, SCK, /ChipSelect, /reset, name

    lcd.puts(0,0,
        "RA8875 lcd(p5, p6, p7, p12, NC, \"tft\");\r\n\r\n"
        "lcd.circle(       400,25,  25,  BrightRed);\r\n"
        "lcd.fillcircle(   400,25,  15,  RGB(128,255,128));\r\n"
        "lcd.ellipse(      440,75,  35,20, BrightBlue);\r\n"
        "lcd.fillellipse(  440,75,  25,10, Blue);\r\n"
        "lcd.triangle(     440,100, 475,110, 450,125, Magenta);\r\n"
        "lcd.filltriangle( 445,105, 467,111, 452,120, Cyan);\r\n"
        "lcd.rect(         400,130, 475,155,    Brown);\r\n"
        "lcd.fillrect(     405,135, 470,150,    Pink);\r\n"
        "lcd.roundrect(    410,160, 475,190, 10,8, Yellow);\r\n"
        "lcd.fillroundrect(415,165, 470,185,  5,3, Orange);\r\n"
        "lcd.line(         430,200, 460,230, RGB(0,255,0));\r\n"
        "for (i=0; i<=30; i+=5)\r\n"
        "    lcd.pixel(435+i,200+i, White);");

    lcd.circle(       400,25,  25,               BrightRed);
    lcd.fillcircle(   400,25,  15,               RGB(128,255,128));
    lcd.ellipse(      440,75,  35,20,            BrightBlue);
    lcd.fillellipse(  440,75,  25,10,            Blue);
    lcd.triangle(     440,100, 475,110, 450,125, Magenta);
    lcd.filltriangle( 445,105, 467,111, 452,120, Cyan);
    lcd.rect(         400,130, 475,155,          Brown);
    lcd.fillrect(     405,135, 470,150,          Pink);
    lcd.roundrect(    410,160, 475,190, 10,8,    Yellow);
    lcd.fillroundrect(415,165, 470,185,  5,3,    Orange);
    lcd.line(         430,200, 460,230,          RGB(0,255,0));
    for (i=0; i<=30; i+=5) 
        lcd.pixel(435+i,200+i, White);
    while (1)
        ;
}

Revisions of main.cpp

Revision	Date	Message	Actions
19:222ca90808c4	2019-07-28	Update demo to latest lib	File Diff Annotate
18:307303d9c8f6	2019-03-04	Update RA8875 Lib to add GSL1680 support.	File Diff Annotate
17:c8ef96a6e43b	2017-08-06	Update libs. RA8875 v148, mbed v137.; Any newer mbed lib works ok for graphics, fails for file write to local file system for printscreen.	File Diff Annotate
16:231837aa2c37	2017-08-06	Updates verified with mbed v128, RA8875 v148	File Diff Annotate
15:ab07c064c952	2016-08-06	Update to latest libraries and test with both 480x272 and 800x480 screens.	File Diff Annotate
14:07b3f223d9ba	2016-05-03	Updated RA8875 and mbed libraries	File Diff Annotate
13:43cc0a997c53	2016-03-05	Updated libs and tested both 8 and 16-bpp.	File Diff Annotate
12:e8a127d78000	2016-01-23	update libs	File Diff Annotate
11:2fcc3ee75ebd	2016-01-23	update libs	File Diff Annotate
10:be714b7f0644	2016-01-23	Updated to v112 of mbed lib.	File Diff Annotate
9:02c622fa4969	2016-01-23	Fixed a class and method name error in the print screen registration.	File Diff Annotate
7:1002bb8871c0	2015-12-19	Updated demo based on updated RA8875 library.	File Diff Annotate
6:8e392d0ff74a	2015-12-17	Update with test mode disabled.	File Diff Annotate
5:bb970d40cd7d	2015-12-17	Demonstration for Soft Font support.	File Diff Annotate
3:ca6a1026c28e	2014-12-28	Minor updates to match the RA8875 library updates.	File Diff Annotate
2:2076d9cc6db9	2014-01-17	Simplify the example, so it shows the program on the screen.	File Diff Annotate
0:037b95a5cc85	2014-01-17	Demo Program	File Diff Annotate