tft lcd 2.4 mcufriend stm32f103 supplier

I am trying to interface a touch scren lcd with stm32 board. I have an mcufriend 2.4" touch screen lcd and i intend to interface it with nucleo-f303re board. I ,unfortunately, am not able to find a datasheet for the lcd. I know that the lcd can be interfaced with spi. but as i mentioned i do not have any datasheet for the lcd. Does anyone has any information on where to find the datasheet or a library for the lcd?

This note introduces a low-cost Thin Film Transistor (TFT) display to enhance the operation and usefulness of Liquid Crystal Display(LCD) devices. TFT technology controls the pixel element on the glass surface thereby greatly reducing image blurring and improving viewing angles.

The test board chosen for this exercise is the Elegoo Arduino UNO board from the corresponding Super Starter Kit. The kit already has several simple numeric and text displays. The TFT display may perhaps provide better ways to interact in applications.

The controller for the illustrated model of the TFT display is SSD1297.This information is important because the display (owing to its low cost and high popularity) has many different manufacturers who may not leverage the same controller instruction set. The specification of the controller in the coding exercises is examined in the Appendix section of this note.

The output from the diagnostic program, LCD_ID_reading.ino, is shown below:Read Registers on MCUFRIEND UNO shieldcontrollers either read as single 16-bite.g. the ID is at readReg(0)or as a sequence of 8-bit valuesin special locations (first is dummy)reg(0x0000) 97 97ID: ILI9320, ILI9325, ILI9335, ...reg(0x0004) 97 97 97 97Manufacturer IDreg(0x0009) 97 97 97 97 97Status Registerreg(0x000A) 97 97Get Power Modereg(0x000C) 97 97Get Pixel Formatreg(0x0061) 97 97RDID1 HX8347-Greg(0x0062) 97 97RDID2 HX8347-Greg(0x0063) 97 97RDID3 HX8347-Greg(0x0064) 97 97RDID1 HX8347-Areg(0x0065) 97 97RDID2 HX8347-Areg(0x0066) 97 97RDID3 HX8347-Areg(0x0067) 97 97RDID Himax HX8347-Areg(0x0070) 97 97Panel Himax HX8347-Areg(0x00A1) 97 97 97 97 97RD_DDB SSD1963reg(0x00B0) 97 97RGB Interface Signal Controlreg(0x00B4) 97 97Inversion Controlreg(0x00B6) 97 97 97 97 97Display Controlreg(0x00B7) 97 97Entry Mode Setreg(0x00BF) 97 97 97 97 97 97ILI9481, HX8357-Breg(0x00C0) 97 97 97 97 97 97 97 97 97Panel Controlreg(0x00C8) 97 97 97 97 97 97 97 97 97 97 97 97 97GAMMAreg(0x00CC) 97 97Panel Controlreg(0x00D0) 97 97 97Power Controlreg(0x00D2) 97 97 97 97 97NVM Readreg(0x00D3) 97 97 97 97ILI9341, ILI9488reg(0x00D4) 97 97 97 97Novatek IDreg(0x00DA) 97 97RDID1reg(0x00DB) 97 97RDID2reg(0x00DC) 97 97RDID3reg(0x00E0) 97 97 97 97 97 97 97 97 97 97 97 97 97 97 97 97GAMMA-Preg(0x00E1) 97 97 97 97 97 97 97 97 97 97 97 97 97 97 97 97GAMMA-Nreg(0x00EF) 97 97 97 97 97 97ILI9327reg(0x00F2) 97 97 97 97 97 97 97 97 97 97 97 97Adjust Control 2reg(0x00F6) 97 97 97 97Interface Control

I bought four MCU Friend 3.5″ TFT shields.  And, unfortunately, they have spiraled me into a deep, dark place trying to figure out how to use them.  The the documentation consists of a sticker on the antistatic bag, a picture of the shield with a list of 5 different possible LCD drivers, a pinout, and a block of code that supposedly represents the startup code.  The unfortunate part is that none of these have been exactly right – they all have errors.  This article is a description of the journey to figuring out how to use them.

It also has a picture which says the LCD has one of several different controllers (and after digging in I know for a fact that two of mine were made by Raydium and are not on the list)

The first thing I did was try to use the MCUFRIEND_kbv library to see if the screens worked.  The first board identified as ID=0x9403 and did not work.  Apparently, the tool just spits out the ID if it doesn’t know it, which it did not.

One of the boards identified as ID=0x6814 worked perfectly, and one had a blue cast to all of the screens.  The crazy part is the two boards that identified as ID=0x6814 had different PCBs.  According to the comments in the MCUFRIEND_kbv.cpp ID=0x6814 is an RM68140 and ID=9403 is unknown.

Next, I started down the path of trying to figure out what the controllers were by using register reads.  David Prentice (the guy who wrote/maintains the MCU Friend_kbv Arduino library) has an absolute ton of responses on the Arduino forum trying to help people figure out what their shield is.  He asks them to post the register report from his example program LCD_ID_readnew which is included as an example in the library.

When you look at these LCD controllers they all have some variant of “Read ID” which responds with 1-6 bytes.  The basic idea of this program is to look at what bytes are returned to try to identify the controller.  Here is an example of what I got when I ran the LCD_ID_readnew program on my shields:

The key thing to see in this output is the register 0x04 which says 54,80,66 which identifies this as a Raydium RM68140 LCD controller.  Here is a snapshot from the data sheet.

After digging some more, I decided that it is super ugly out there, as you find that there are a significant number of LCD controllers that are clones, copies, pirated etc… and that they all present themselves differently.  And, in hindsight I think that this is the reason that my ILI9341 from the previous article doesnt quite work correctly.

The next thing that I did was try out the startup code that MCUFriend_kbv generates.  I used the same technique from PSoC 6 + Segger EmWin + MCUFriend 2.4″ Part 1 and spit out the startup bytes.  Here they are:

At this point I have spent a frightening amount of time figuring out how these screens work.  Although it has been a good learning experience, I have generally decided that using unknown displays from China with LCD drivers of questionable origin is not worth the pain of trying to sort out the interface.  Beyond that:

Before I start, I want to mention that I did not write this code. This is a PORT from the mcufriend’s arduino code, which can be found HERE. I merely made some changes, so that it can be used with the CubeMx with a little modifications.

According to the Setup, the LCD_D2 is connected to the PA15. So if I want to write the DATA to the LCD_D2 pin, first I will select the 2nd bit of the data (d & (1<<2)), and than shift this by 13 using <<13. This will be like adding 2 with 13 to make a total of 15, and that’s where the LCD_D2 is connected to.

Similarly, LCD_D7 is connected to PA5. So to write the data, first we will select the 7th bit of the data (d & (1<<7)), and this time shift it RIGHT by 2 (>>2). This is like subtracting 7-2=5. And that’s where, the D7 is connected to.

The process here remains the same. Except, we have to first select the GPIO Pin, and than shift it according to the position of the LCD Pin, that it is connected to. In the function above, we are first selecting the PB0 pin, and as it is connected to LCD_D0, we don’t need to shift it anywhere. Same for the PB1 also.

Next, we are selecting PA15, and as this one is connected to the LCD_D2, we need to shift it by 13 to the right ( >>13). This process continues for all other pins too.

After all the Pins work is done, we still need to select the delays according to our clock frequency. As I am using STM32F103C8 at72 MHz, I am going to uncomment the respective code as shown below.