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Diskussions- und Newsboard des DARC-Ortsverbandes I40  |  allgemeine Kategorie  |  UHSDR Firmware (Moderators: DF8OE, DL1PQ)  |  Topic: Benchmark for LCD. <- zurück vorwärts ->
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DF8OE
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Re:Benchmark for LCD.
« Reply #15 on: 05. December 2018, 05:29:30 »

My two benchmarks in one post are for parallel use. The single benchmark is for SPI - but I think I will revert this device to parallel back because of RF interference and speed args some times...

I have done the maths ~ a year ago and I think we are near at the edge regarding theoretical maximum speed of SPI at the real usage in UHSDR (button boxes, waterfall, scope). It is not possible to blow up the speed by simply changing the prescaler because a reasonable amount of LCDs does not work with higher clock. I bymyself do think that an improvement of x2 is recognizeable - but swapping to parallel will do the job much better. Because of OVI40 only works in parallel mode anything regarding SPI speed does not affect anything there.

vy 73
Andreas
« Last Edit: 05. December 2018, 07:59:59 by DF8OE » Logged

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Re:Benchmark for LCD.
« Reply #16 on: 05. December 2018, 07:55:07 »

Quote from: RV9YW on 05. December 2018, 03:32:40
BTW, does any one see that 8bitFont is not working properly? Or it's only on my side?

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
« Last Edit: 05. December 2018, 07:58:16 by SP9BSL » Logged

73 Slawek
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Re:Benchmark for LCD.
« Reply #17 on: 22. December 2018, 18:44:49 »

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
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Re:Benchmark for LCD.
« Reply #18 on: 22. December 2018, 21:15:31 »

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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DF8OE
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Re:Benchmark for LCD.
« Reply #19 on: 23. December 2018, 11:35:39 »

Hi Max,

additional info:
I have got a LCD panel where we do have access to complete pins of ILI9486 controller. My idea was to configure SPI or parallel use on LCD PCB. So this panel is "standard panel" for OVI40 actual (but only in parallel mode). Hardware implementation may be usable now - 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. You have to write bit banging code and transform data before shifting it to LCD. This would slow down complete process much and would result in not-usable speed...

vy 73
Andreas
« Last Edit: 23. December 2018, 13:30:12 by DF8OE » Logged

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Re:Benchmark for LCD.
« Reply #20 on: 23. December 2018, 11:44:01 »

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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Re:Benchmark for LCD.
« Reply #21 on: 23. December 2018, 17:39:21 »

Quote from: DF8OE on 23. December 2018, 11:35:39
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

Sorry, did not get what do you mean exactly!?
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RV9YW
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Re:Benchmark for LCD.
« Reply #22 on: 23. December 2018, 17:50:09 »

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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Re:Benchmark for LCD.
« Reply #23 on: 23. December 2018, 17:54:25 »

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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DF8OE
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Re:Benchmark for LCD.
« Reply #24 on: 23. December 2018, 18:29:44 »

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.

EDIT:
Parcel has left Germany ~14 days ago. Unfortunately I cannot get tracking informations outside Germany. This is not uncommon - I do have many shipments where tracking was lost but parvel arrives in spite of this.

vy 73
Andreas
« Last Edit: 23. December 2018, 18:40:47 by DF8OE » Logged

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Re:Benchmark for LCD.
« Reply #25 on: 23. December 2018, 18:40:03 »

Quote from: DF8OE on 23. December 2018, 18:29:44
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
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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DF8OE
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Re:Benchmark for LCD.
« Reply #26 on: 23. December 2018, 18:43:00 »

No - I am talking about *9bit* for 3 line SPI which is an approach to standard SPI. I do not know 4 line SPI with a "command switching line" which can work with 8/16 bit.

vy 73
Andreas
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Re:Benchmark for LCD.
« Reply #27 on: 23. December 2018, 18:44:44 »

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...
« Last Edit: 23. December 2018, 18:48:21 by SP9BSL » Logged

73 Slawek
DF8OE
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Re:Benchmark for LCD.
« Reply #28 on: 23. December 2018, 18:48:20 »

Problems are:
1) ILI9486's electrical pin assignment is not SPI at all but very strange serial communication
2) used data format is completely different to ILI9341 SPI

vy 73
Andreas
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Re:Benchmark for LCD.
« Reply #29 on: 23. December 2018, 20:35:11 »

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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