Driver Problem

Current License: CC BY-SA 4.0

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Nov 18, 2019 at 6:51	history	edited	tlfong01	CC BY-SA 4.0	added 57 characters in body
Oct 19, 2019 at 14:19	history	edited	tlfong01	CC BY-SA 4.0	added appendix A ili9341 wiring
Jun 3, 2019 at 4:58	history	edited	tlfong01	CC BY-SA 4.0	added more references on kernel modules and drivers
May 22, 2019 at 13:04	history	edited	tlfong01	CC BY-SA 4.0	added reason for testing 4 bit mode.
May 22, 2019 at 12:57	history	edited	tlfong01	CC BY-SA 4.0	added reason for testing 4 bit mode.
May 21, 2019 at 13:03	comment	added	tlfong01		You are welcome. I am still studying the juj driver document on how to build the kernel module. I have no experience of building any linux kernel module. So I am going very slowly. I have also diverted to a test on controlling a LCD 20 char x 4 line module using 4 bit interface. This is a warm up and memory refreshing exercise in case I need to switch from SPI mode to 8bit mode for faster response. You might like to come back from time to time to see my progress.
May 21, 2019 at 12:58	history	edited	tlfong01	CC BY-SA 4.0	copyediting of the short answer
May 21, 2019 at 11:14	comment	added	Ephemeral		Thank you very much again for all this information.
May 20, 2019 at 4:19	history	edited	tlfong01	CC BY-SA 4.0	added ici9341 wiring worksheet
May 19, 2019 at 7:31	comment	added	tlfong01		Some clarifications: (1) There are two types of ILI9341 Arduino shields, one for Arduino Uno or similar, another for Mega 2560. You board is for 2560, which might not fit if you are using Uno. (2) There are two SPI wiring methods, 3 wires method does not use DC signal. (3) MISO is always not used. The details can be found in the driver tutorial below: github.com/juj/fbcp-ili9341
May 19, 2019 at 7:25	history	edited	tlfong01	CC BY-SA 4.0	added tutorial on how to build kernel module for led module.
May 19, 2019 at 3:02	history	edited	tlfong01	CC BY-SA 4.0	tidying up, restructuring, and formatting.
May 19, 2019 at 2:30	history	edited	tlfong01	CC BY-SA 4.0	minor editing
May 19, 2019 at 2:25	history	edited	tlfong01	CC BY-SA 4.0	minor editing
May 19, 2019 at 2:15	history	edited	tlfong01	CC BY-SA 4.0	added ici9341 cable v3.0 picture
May 18, 2019 at 13:48	comment	added	tlfong01		@Ephemeral Ah you remind me another user commenting that my very long answer to his short questions is like a blog. My reply was that I used to hesitate to give an answer which I am not very sure correct. So I usually say, pretty sure, 60% chance and so on. If it happens that the question is related to my own project, then I would do some research as in this touch LCD case. Actually I am at the same time researching on 20 char x 4 line LCD with buttons. I know 20x4 LCD very well, but only using Arduino C++, so I need to try on Rpi python to make sure, otherwise I am misleading the OP.
May 18, 2019 at 9:25	history	edited	tlfong01	CC BY-SA 4.0	minor editing
May 18, 2019 at 9:18	history	edited	tlfong01	CC BY-SA 4.0	added fbtft_device gitHub
May 18, 2019 at 8:23	history	edited	tlfong01	CC BY-SA 4.0	added record of uploading kernel module fbtft_device name = ici9341
May 18, 2019 at 7:04	history	edited	tlfong01	CC BY-SA 4.0	added back lit test.
May 17, 2019 at 19:51	comment	added	Ephemeral		yes I see that . I follow your updates. This is a complete LCD tut's :)
May 17, 2019 at 9:09	history	edited	tlfong01	CC BY-SA 4.0	added spi signal routing cable
May 17, 2019 at 8:12	history	edited	tlfong01	CC BY-SA 4.0	add spi waveform checking picture
May 17, 2019 at 7:31	history	edited	tlfong01	CC BY-SA 4.0	added arduino shield pinout
May 17, 2019 at 6:51	history	edited	tlfong01	CC BY-SA 4.0	Added SPI loopback test reference to prepare for SPI touch screen testing.
May 17, 2019 at 1:43	comment	added	tlfong01		@Ephemeral Now I have added Fig 8, 9 for vm412 and stm32 signals. Next is to test BL and then SPI.
May 17, 2019 at 1:41	history	edited	tlfong01	CC BY-SA 4.0	added fig 8, 9 lcd signals
May 16, 2019 at 13:28	history	edited	tlfong01	CC BY-SA 4.0	added connector con1 picture
May 16, 2019 at 5:34	history	edited	tlfong01	CC BY-SA 4.0	added adafruit tft 2.8"
May 16, 2019 at 4:52	history	edited	tlfong01	CC BY-SA 4.0	added LCD 4 bit operation program example
May 15, 2019 at 13:17	comment	added	tlfong01		Let us continue this discussion in chat.
May 15, 2019 at 13:16	history	edited	tlfong01	CC BY-SA 4.0	added touch screen hardware setup
May 15, 2019 at 12:45	comment	added	tlfong01		Ah, you only need 4 wires for the LCD - CLK, MOSI, MISO, CS. The 5th wire is CS for the SD card. So actually we don't need to bother the SD card, or even the back lit, just play with LCD to start with. As I said, you can just sit back, do nothing and watch how do I test the very basic SPI thing over the weekend, ...
May 15, 2019 at 11:57	comment	added	Ephemeral		Thank you. I understand you, but I am simply confused because I have a little experience of programming with SPI. On the original vellman diagram, you have highlighted 5 'wires', on the diagram of lallafa's 4 'wires' are highlighted. When I program an ATtiny (which happened to me once or twice) with SPI I use 4 'wires'. I do not try to make all the features of the screen, touchscreen, access to the SD card etc but rather to do a simple SPI link is to write text to start,I have this screen on hand so I thought maybe it's possible to just connect to the raspberry.
May 15, 2019 at 11:45	history	edited	tlfong01	CC BY-SA 4.0	added waveshare touch LCD posts
May 15, 2019 at 11:42	comment	added	tlfong01		Yes, I agree. If you cannot guess the meaning of terms BL = Back Lit, and LEDA, LEDK mean Anode and Cathode, then it is very difficult to do it all by yourself. But then if you read AdaFruit's newbie tutorials on touch LCD, you might find things not that difficult. Or if you search Amazon's touch LCD for Rpi, you might also find it easy. Your problem is now you want to change an Arduino shield to Rpi compatible, that is indeed very difficult. Suggestion: watch what I do this weekend, then decide to give up for now and come back later, after learning SPI basics.
May 15, 2019 at 11:23	comment	added	Ephemeral		Yes I will look even more carefully. After thinking, in fact, I should not rather look at your last schema which is much clearer for me and my level because I can not find a match for the clock for example apart from in your last scheme. If I understand what you told me before then I just miss the pin for the back light. But I am beginning to doubt my ability to properly configure the outputs in the driver source since I can not easily understand a simple connection and associate the technical terms.
May 15, 2019 at 11:14	comment	added	tlfong01		Ah, the four most important spi wires you want is located in CON1. Look for this plug in my picture updated yesterday.
May 15, 2019 at 10:46	comment	added	Ephemeral		Thank you for all your clarifications. For the lighting the schema of the diodes watches a schema with a pin named 'A' and 4 Leds in parallel. It seemed to me that LEDA could have been used for this pin. Yes, you're right, I'm going to read the ILI9341 data sheet provided by adafruit to read a bit more about SPI and I2C. But I do not know if it will allow me to find the connection for the spi clock, the back light etc ... because everything is on the diagram of the screen finally.
May 15, 2019 at 10:35	comment	added	tlfong01		Ah, let us consider one device at a time. A SPI operation is almost always write and read at the same time, sort of mouth talking and ears listening at the same time. So it is full duplex, if you wish to use this term half/full duplex. Same for SD card, you write and read at the same time. Now you can read a byte from LCD and then write the byte to SD. But this has nothing to do with half or full duplex, I think, not very sure, again. You need to wiki for SPI, and also google Rpi newbit tutorials on SPI and I2C etc, to clarify.
May 15, 2019 at 10:29	comment	added	tlfong01		Ah. LEDA means LED Anode, which means Positive. LEDK means LED Cathode, Negative side. So if you connect Anode (to be very safe, use 1k in series to limit current) to 3V3, and Cathode to Gnd, the back lit LED should light up.
May 15, 2019 at 9:22	comment	added	Ephemeral		For SPI it means that I can not make a display request and a request to access the SD card at the same time ? Can we say that this works in half-duplex ?
May 15, 2019 at 9:01	comment	added	Ephemeral		Again, thank you very much. For 'BL', I can see LEDA on pin 16 and LEDK on pin 17 (LEDA seems to be the only pin needed on the diagram), but I really do not understand the pin mapping for the final board. And then what would LEDK be used for ? ... Have a good supper.
May 15, 2019 at 7:29	comment	added	tlfong01		@Ephemeral I googled more touch LCD user guides and found all of them similar. So I have drafted a basic wiring diagram as updated. I think you can find the SPI signal lines at the Arduino shield plug CON 1, and one more CS signal line for micro SD card at the bottom side of the PCB. (Main SPI line are shared between LCD and sd card。） I could not find any BL line in your board. Perhaps your board has no back lit. Or you can try searching for it. I am going to gym then supper. See you late evening or tomorrow. Good luck!
May 15, 2019 at 7:20	history	edited	tlfong01	CC BY-SA 4.0	touch lcd wiring added
May 15, 2019 at 2:31	history	edited	tlfong01	CC BY-SA 4.0	added SPI for TFT Touch Screen wiring suggestion picture
May 14, 2019 at 14:08	history	edited	tlfong01	CC BY-SA 4.0	added waveshare user manual
May 14, 2019 at 14:02	history	edited	tlfong01	CC BY-SA 4.0	added 32 pin socket
May 14, 2019 at 13:16	history	edited	tlfong01	CC BY-SA 4.0	minor editing
May 14, 2019 at 13:09	history	edited	tlfong01	CC BY-SA 4.0	add more pinout diagrams
May 14, 2019 at 12:56	history	edited	tlfong01	CC BY-SA 4.0	added user manuals
May 14, 2019 at 12:19	history	edited	tlfong01	CC BY-SA 4.0	minor editing
May 14, 2019 at 9:22	history	edited	tlfong01	CC BY-SA 4.0	added more adafruit touch screen module references
May 14, 2019 at 9:07	comment	added	Ephemeral		I can not thank you enough. Have a good dinner. I will work with the elements of your updated answer.
May 14, 2019 at 9:02	history	edited	tlfong01	CC BY-SA 4.0	added tft module wiring.
May 14, 2019 at 8:59	comment	added	tlfong01		Yes, it is confusing. I am trying to make some educational guesses, as in the coming updated picture. BTW, my answer is not just for you, but a follow up of other touch screens answers for newbies. For me it is just like a jigsaw puzzle, which is my hobby of playing electronics toys. Now I am going to meet a friend for supper. So see you tomorrow. Have a nice project!
May 14, 2019 at 8:27	comment	added	Ephemeral		Thank you very much again for all your explanations. I think at this time, `GPIO9 -> LCD_RD , GPIO10 -> LCD_WR, GPIO8 -> LCD_CS` but for RESET and RS (Register Select ?) no definition on pinout shematic for the raspberry. Maybe these pins can be any pin gpio (declared in the driver source file?) raspberry pinout
May 14, 2019 at 8:20	comment	added	tlfong01		Ah I see your problem. They are using hard to understand geek language. "NC" usually means "No Connection". “BL” usually means "Back Lit". The module has 4 white LED which can back light the background. No problem for me drawing anything. It take me very littl time.
May 14, 2019 at 7:51	comment	added	Ephemeral		It would be with great pleasure but I would not want to take up too much of your time.
May 14, 2019 at 7:50	comment	added	tlfong01		Ah, no problem. Perhaps I can draw a diagram to explain it better.
May 14, 2019 at 7:47	comment	added	Ephemeral		Thank you very much, I have already seen (hover over) all the tutorials provided but I do not understand how to connect "BL" (from ILI9341 Raspberry Pi guide - pi0cket) for example, I can not see it on the diagram (that you kindly highlighted me). Another remark is for pin SPI_SDO, SPI_SDA there is NC / SPI_, the NC scares me ...
May 14, 2019 at 5:12	history	edited	tlfong01	CC BY-SA 4.0	added wiring diagram.
May 14, 2019 at 4:01	history	edited	tlfong01	CC BY-SA 4.0	add aliexpress touch screen web link
May 14, 2019 at 3:30	history	edited	tlfong01	CC BY-SA 4.0	added reference links of the OP's touch screen
May 14, 2019 at 3:18	history	edited	tlfong01	CC BY-SA 4.0	added wiring diagram
May 14, 2019 at 2:57	history	answered	tlfong01	CC BY-SA 4.0

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