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Forum Index : Microcontroller and PC projects : PicoMite: ILI9341 TFT with parallel interface

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thwill

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Posted: 03:39pm 13 Sep 2023
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Hi folks,

Before I buy one to have a play:
   https://www.aliexpress.com/item/1005005541885265.html

Is there a technical reason that the PicoMite only has an SPI driver for the ILI9341, or is it just a case of nobody has written a Parallel driver ?

Or is there a Parallel driver and I've got a blindspot when looking at the manual, or am otherwise fundamentally daft?

Best wishes,

Tom
Edited 2023-09-14 01:44 by thwill
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Mixtel90

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Posted: 03:50pm 13 Sep 2023
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It was just the number of available pins, that's all. I think the PicoMite supports the SSD1963 but you get very few pins left to do anything else with. AFAIK that's the only parallel display that's supported on any MMBasic platform to date.
Mick

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thwill

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Posted: 03:55pm 13 Sep 2023
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My use case would only need 5 pins left over to drive a shift register and audio. The SSD1963 panels are all larger, and of a different resolution than I want.

Best wishes,

Tom
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Mixtel90

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Posted: 04:01pm 13 Sep 2023
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I suspect it wouldn't be beyond the whit of man to produce a driver based on the SSD1963 one. I did a backpack board ages ago that used a second PicoMite on I2C to get the IO pins back. :)  (Unfortunately I've lost the files for that one. It was a work of art too! It was the victim of a couple of failed USB sticks.)
Mick

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thwill

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Posted: 04:07pm 13 Sep 2023
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  Mixtel90 said  I suspect it wouldn't be beyond the whit of man to produce a driver based on the SSD1963 one ...


You'd hope so, but whilst I don't expect Peter to implement a driver it is possible he might save me some head scratching by telling me that he has already tried and X isn't possible (or is a fundamentally flawed idea) because of Y ... which on reflection is usually a preamble for him doing X, but I'm honestly not asking for that.

Best wishes,

Tom
Edited 2023-09-14 02:07 by thwill
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stanleyella

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Posted: 04:28pm 13 Sep 2023
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The spi ili9341 is not slow in real time but blit and sprite will not be smooth as parallel interface but less wiring to mess up :)
 
thwill

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Posted: 04:32pm 13 Sep 2023
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  stanleyella said  The spi ili9341 is not slow in real time but blit and sprite will not be smooth as parallel interface but less wiring to mess up :)


Hi Stan,

I'm familiar with the SPI display, it's what the Game*Mite uses, however updating the display is a bottleneck on what sort of games can be written for the Game*Mite, hence my interest in investigating alternatives in the future.

Tom
Edited 2023-09-14 02:35 by thwill
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Mixtel90

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Posted: 05:23pm 13 Sep 2023
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That looks like an interesting display - it has the same pinout as the SSD 1963.
Mick

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stanleyella

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Posted: 06:08pm 13 Sep 2023
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I can't see the point of i2c to parallel. I got one working with mmbasic but isn't that pointless? https://www.microchip.com/en-us/product/mcp23017
I got a 5 button pad that uses 1 adc pin and works.
https://www.aliexpress.com/item/1005005035048967.html?
 
matherp
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Posted: 06:14pm 13 Sep 2023
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The selection of the interface mode on an ILI9341 is set by 4 pins IM0 to IM3. Unless these pins are made available on a carrier PCB then it isn't possible to change the communication mode. The version pictured appears to be set up for 16-bit parallel. Unlike the SSD1963 you can't use 8-bit mode if configured in H/W for 16-bit.
The only 8-bit form-factor ILI9341 I'm aware of have Arduino  pinout and no touch controller

NB: the ArmmiteF4 supports 16-bit parallel ILI9341
Edited 2023-09-14 04:26 by matherp
 
stanleyella

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Posted: 06:26pm 13 Sep 2023
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  Mixtel90 said  I suspect it wouldn't be beyond the whit of man to produce a driver based on the SSD1963 one. I did a backpack board ages ago that used a second PicoMite on I2C to get the IO pins back. :)  (Unfortunately I've lost the files for that one. It was a work of art too! It was the victim of a couple of failed USB sticks.)

USB sticks and ssd drives go duff just like that for no apparent reason. Mechanical usb drives seem to last years. I use a 2TB usb hdd from Maplin connected to my tv and no probs yet.
 
Mixtel90

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Posted: 06:51pm 13 Sep 2023
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Ah.... I'd forgotten that the SSD1963 was in 8-bit mode on the PicoMite.
I don't think Tom will want to change boards at this point. :)
He may not be bothered about touch though.
Mick

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thwill

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Posted: 08:17pm 13 Sep 2023
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Thanks Peter (& Mick),

I knew there must be a "gotcha" or given how cheap and popular ILI9341 boards are it would have been posted about before.

There is some suggestion that the IM# interface select pins may be accessible on some of the ribbon versions but those look harder to source and tricky for a hobbyist to deal with.

The lack of touch on the Arduino board wouldn't be a big issue, but it doesn't seem to be available in 3.2".

  Mixtel90 said  I don't think Tom will want to change boards at this point. :)


This isn't for "this point", the Game*Mite v1 (hopefully "released" on/by next Monday) uses an SPI display and I think I'm probably going to be quite happy with that and its limitations will just be part of the fun.

I was instead considering where I might go next with the hardware and it had registered for the first time that some of the ILI9341 were being advertised as parallel displays. I don't think I'll be looking at an MCU other than the Pico though simply because it comes on the smallest breakout boards.

Best wishes,

Tom
Edited 2023-09-14 07:26 by thwill
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Turbo46

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Posted: 05:52am 14 Sep 2023
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I searched for "ili9341 3.2 parallel" and found a few that may be suitable here and here They claim to be 8/16 bit compatible. Both are the same type and there are more.

All you need id a driver.  

Bill
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matherp
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Posted: 06:11am 14 Sep 2023
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This version has the relevant IM pins broken out so can be properly configured for 8-bit operation. If anyone wants to send me one I'll get it working on the Pico
 
Mixtel90

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Posted: 06:57am 14 Sep 2023
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Also from Made in China and AliExpress
Edited 2023-09-14 17:00 by Mixtel90
Mick

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thwill

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Posted: 08:20am 14 Sep 2023
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Thanks guys,

Ironically the first module I found was the 8/16 bit 3.2" one: https://www.aliexpress.com/item/1005003505981991.html (much cheaper than the one Mick linked) but then because I was on my phone I proceeded to post about the smaller one assuming it was the same iface - and then because I was expecting there to be a gotcha I didn't look carefully enough after Peter's initial reply - a little knowledge is a dangerous thing.

  matherp said  If anyone wants to send me one I'll get it working on the Pico


I'll put a couple in my next AliExpress basket, but unless that's a time limited offer I'd quite like to have a go myself first ?

Best wishes,

Tom
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Volhout
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Posted: 08:52am 14 Sep 2023
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Tom,

If you connect this display in 8bit mode and want to use touch and SD card (I assume you do) you need minimal 19 pins from pico. This is minimal, excludes backlight control.

When you plan a game console application (sound uses 2 pins PWM or 3 when MCP4822 DAC), it would just leave 3 pins for a CD4021 for the NES controler / 2xCD4021 for SNES controller. It is possible, but pico is completely FULL....

Volhout



Edited 2023-09-14 18:53 by Volhout
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matherp
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Posted: 09:00am 14 Sep 2023
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Supporting this would be best with a custom PC like my PicoMiteVGA boards with the RP2040 direct mounted. This frees up 3 or 4 extra pins (depending on whether you keep the heartbeat).
 
thwill

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Posted: 09:27am 14 Sep 2023
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We're getting ahead of ourselves, the Game*Mite v1 hasn't quite been pushed out of the door yet. I'm just thinking about what I might do hardware-wise in the next 12-24 month period.

  Quote  When you plan a game console application (sound uses 2 pins PWM or 3 when MCP4822 DAC), it would just leave 3 pins for a CD4021 for the NES controler / 2xCD4021 for SNES controller. It is possible, but pico is completely FULL....


That was my calculation too. FULL is fine, it's FULL + 1 that would be the problem. I'd need the SD card but probably skip touch or at least connect it via solder jumpers so its pins could alternatively be brought out to a small expansion port.

  Quote  Supporting this would be best with a custom PC like my PicoMiteVGA boards with the RP2040 direct mounted. This frees up 3 or 4 extra pins (depending on whether you keep the heartbeat).


Absolutely, and with the battery charger and amplifier all SMD on the PCB instead of using Chinesium modules. However I'm principally a software guy and can't even layout my own PCB at the moment (many thanks to @bigmik for the Game*Mite v1), are you volunteering ?

Best wishes,

Tom
Edited 2023-09-14 19:42 by thwill
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