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Topic: Benchmark for LCD. (Read 4913 times)
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SP9BSL
positron alter Hase
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Posts: 443
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Re:Benchmark for LCD.
« Reply #16 on: 05. December 2018, 07:55:07 »
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BTW, does any one see that 8bitFont is not working properly? Or it's only on my side?
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Hi Maksim, the 8 bit font was defined only for digits and a dot. That's because 8bit bitmap needs memory, and currently we don't need them for other purposes than freq display. You may see the fonts working looking for pictures here in the forum, or on Aliexpress with RS928
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« Last Edit: 05. December 2018, 07:58:16 by SP9BSL » |
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73 Slawek
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RV9YW
Neuling
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Posts: 15
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Re:Benchmark for LCD.
« Reply #17 on: 22. December 2018, 18:44:49 »
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Hi Danilo, could you help. In UiLcdHy28_ReadDisplayId_ILI9486() there is a comment such - "// we can't read the id from SPI if it is the dumb RPi SPI"
What's the problem? because this type of displays do use the shift registers to implement SPI interface over normal 8080? or because ILI9486 and ILI9486L are using SPI in half-duplex mode (one pin SDA for sending and receiving data )?
thank's
Max 73
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DB4PLE
positron Urgestein
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Posts: 1278
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Re:Benchmark for LCD.
« Reply #18 on: 22. December 2018, 21:15:31 »
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Hi Max,
the reason is that these displays are connected using simple shiftregisters (i.e. it is a unidirectional, write-only SPI). It is impossible to test for existence of this particular display controller configuration. That is way it needs to be last in the list. The main reason to support it is the availability (search for 3.5 RPI SPI touchscreen display)
73 Danilo
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DB4PLE
positron Urgestein
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Posts: 1278
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Re:Benchmark for LCD.
« Reply #20 on: 23. December 2018, 11:44:01 »
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Hi,
the weird SPI protocol is the main reason (IMHO) why the chinese manufacturers added extra components on the pcb to implement a simple SPI to PARALLEL converter instead of just exposing the controllers "SPI". They would never do this unless there is a good reason for it (it costs extra money).
73 Danilo
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RV9YW
Neuling
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Posts: 15
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Re:Benchmark for LCD.
« Reply #21 on: 23. December 2018, 17:39:21 »
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Hi Max, ... but if you look at the controllers datasheet you will see a very strange data and handshaking protocol which is not supported by anc MCU... vy 73 Andreas
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Sorry, did not get what do you mean exactly!?
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RV9YW
Neuling
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Posts: 15
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Re:Benchmark for LCD.
« Reply #22 on: 23. December 2018, 17:50:09 »
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I take a look one more times, looks the same as for ili9341. I found only one incompatible thing with STM32 SPI is that they are required different number of dummy clocks for different read sequences.
Did I miss something more?
BTW, guys what kind of displays do you have handy to help me with tests? I wrote driver for ILI9341 and test with it, I'm waiting EVO40 kit for testing with display from it, but looks like it stuck in Frankfurt am Main...
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RV9YW
Neuling
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Posts: 15
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Re:Benchmark for LCD.
« Reply #23 on: 23. December 2018, 17:54:25 »
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In my code I removed reverse like this
// for (uint32_t i = 0; i < len; i++) // { // pixel[i] = __REV16(pixel[i]); // reverse byte order; // }
because I'm using SPI in 16bit mode, so no need to do it. Andreas, did you mean this?
Max, 73
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RV9YW
Neuling
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Posts: 15
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Re:Benchmark for LCD.
« Reply #25 on: 23. December 2018, 18:40:03 »
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Pse take a look at page 32 of ILI9486 datasheet. There you can find strange data line assignment and data format under 7.1.3. This has nothing to do with SPI as we know and is used on STM.
vy 73 Andreas
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| Do you mean one line SDA for bidirectional communication? If so, the stm SPI can do it also, it calls half-duplex in STM datasheet, as I remember.
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SP9BSL
positron alter Hase
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Posts: 443
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Re:Benchmark for LCD.
« Reply #27 on: 23. December 2018, 18:44:44 »
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Hi Maksim, please be aware of touchscreen communication which uses the same SPI port as we have for display. If using bidirectional data we must continously reconfigure the SPI (if possible at all).
Edit: if you have any idea, and prove it works then why not? We spent some time on it (well Danilo tried) without success...
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« Last Edit: 23. December 2018, 18:48:21 by SP9BSL » |
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73 Slawek
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DB4PLE
positron Urgestein
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Posts: 1278
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Re:Benchmark for LCD.
« Reply #29 on: 23. December 2018, 20:35:11 »
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Hi Max,
I don't think it is worth your and our time to provide a direct serial connection to the ILI9486. But since this is a hobby and you can do what you want, let's think this through.
- As Andreas said, due to the shared SPI between touchscreen and display, we need to reprogram the SPI controller for the different modes. We already do this in a very limited fashion, needs to be checked if this is not eating too much time. Just work.
- I don't exactly remember why I decided to stop working on it, I knew about the 9bit capability and tried to figure out how to use it. But at some point could not bring the things together in my head. But I may just not have been smart enough to see the solution. I am very sure, the reprogramming was not the reason, that is solvable.
73 Danilo
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