Need help in buying a display for Teensy 3.6

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Need help in buying a display for Teensy 3.6

Postby Zvoc47 » Tue Jun 13, 2017 9:21 pm

Hello.
I'm finally going to buy a Teensy 3.6 board. I'm wondering what kind of a display would be good for it.
The display that I need needs to be at least 220x178 and have at least 256 colors. The display shouldn't have any kind of tearing effects or slow upload speed. I'm not sure should I buy an SPI display or a parallel display because I don't know if Teensy has a parallel bus like XMEGA. Does Teensy have a parallel bus DMA? If the display is SPI, what do you think if I use DMA and SPI to blit a framebuffer located on Teensy's RAM onto the display? Is it effective? What kind of a screen has a fast enough SPI to receive a whole frame before the tearing effect occurs? Does anyone have a video with a tech demo showing these requirements?

So far I have ST7775 and NT931-something-I-don't-know and both use 5V for the background LED and 3.3V for power and I/O which confuses me as I cannot supply both 3.3V and 5V from my Arduino. If I use 5V, the screen doesn't work and if I use 3.3V, the backlight is so weak that it's hard to see the picture. Does Teensy have a 5V pin along with the 3.3V I/O?

Please tell me what you think. Thank you!
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Re: Need help in buying a display for Teensy 3.6

Postby awesome101 » Tue Jun 13, 2017 11:06 pm

Buy a ILI9341 WITH SPI! Do not buy the 8 bit parallel ones because they waste GPIO pins on the Teensy 3.6. It is also difficult or maybe even impossible to set up DMA with the parallel bus because data cannot be sent without the write pin being strobed. If you do choose to use a ILI9341 with the parallel bus, you can use my library (https://github.com/LudumDareDevelopment ... el-Library) which is generally faster than the default ILI9341_t3 SPI library for the Teensy. The fastest library and what I recommend is the Teensy 3.6 ILI9341 DMA SPI framebuffer library since it is extremely fast and can do updates above 50HZ. You can find the library here: https://forum.pjrc.com/threads/36706-IL ... y-3-6-only
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Re: Need help in buying a display for Teensy 3.6

Postby awesome101 » Tue Jun 13, 2017 11:11 pm

Also, instead of the Teensy 3.6, I would buy the ESP32 since it's power efficient (it has a deep sleep mode) and is faster and cheaper. It also has SPI DMA transactions. I may be able to write a library for you that has fast refresh rates with no tearing
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Re: Need help in buying a display for Teensy 3.6

Postby Zvoc47 » Wed Jun 14, 2017 5:01 pm

awesome101 wrote:Buy a ILI9341 WITH SPI! Do not buy the 8 bit parallel ones because they waste GPIO pins on the Teensy 3.6. It is also difficult or maybe even impossible to set up DMA with the parallel bus because data cannot be sent without the write pin being strobed. If you do choose to use a ILI9341 with the parallel bus, you can use my library (https://github.com/LudumDareDevelopment ... el-Library) which is generally faster than the default ILI9341_t3 SPI library for the Teensy. The fastest library and what I recommend is the Teensy 3.6 ILI9341 DMA SPI framebuffer library since it is extremely fast and can do updates above 50HZ. You can find the library here: https://forum.pjrc.com/threads/36706-IL ... y-3-6-only

As far as I can see, this display lets me choose when I want to refresh the screen. So if I want 30 frames per second, I should set a timer on Teensy to send the refresh command every 1/30th of a second?
awesome101 wrote:Also, instead of the Teensy 3.6, I would buy the ESP32 since it's power efficient (it has a deep sleep mode) and is faster and cheaper. It also has SPI DMA transactions. I may be able to write a library for you that has fast refresh rates with no tearing
Are you sure it's faster? Teensy 3.6 can go up to 240MHz while ESP32 can go up to 180MHz. Does ESP32 have a FPU? How do I load games onto it when compared with Gamebuino? I'd like to have some kind of a bootloader which either loads a game into Flash or RAM, but in a way that doesn't let the bootloader or the game overwrite the bootloader. Are programs for this microcontroller compilable in a way that they can be loaded to RAM with all of the code segments fitting nicely to not overwrite the bootloader's RAM code? Does ESP32 have MMU?

http://www.ebay.com/itm/ESP-32S-ESP32-D ... Swax5Y1OV3
Is this a good example of the board to buy?
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Re: Need help in buying a display for Teensy 3.6

Postby awesome101 » Thu Jun 15, 2017 4:13 pm

Not sure what you mean by
Teensy 3.6 can go up to 240MHz while ESP32 can go up to 180MHz
? The ESP32 is clocked at 240MHZ and is generally faster. It also includes WIFI and other IOT stuff that could be useful. The ESP32 also obviously has both a hardware MMU and FPU. As for the bootloader, no one has written that for the Teensy or ESP32 so you may have to write that yourself.
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Re: Need help in buying a display for Teensy 3.6

Postby awesome101 » Thu Jun 15, 2017 4:19 pm

Also, for the backlight and anything that needs 5V input, connect it to the VUSB or VIN pin and it will work. You can find the schematics for the Teensy here: https://www.pjrc.com/teensy/schematic.html
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Re: Need help in buying a display for Teensy 3.6

Postby Zvoc47 » Thu Jun 15, 2017 8:04 pm

awesome101 wrote:Not sure what you mean by
Teensy 3.6 can go up to 240MHz while ESP32 can go up to 180MHz
? The ESP32 is clocked at 240MHZ and is generally faster. It also includes WIFI and other IOT stuff that could be useful. The ESP32 also obviously has both a hardware MMU and FPU. As for the bootloader, no one has written that for the Teensy or ESP32 so you may have to write that yourself.
Wow! Just wow! I'm buying this! Forget Teensy! ESP32 is cool now. I read somewhere that FreeRTOS is made for ESP32. I don't know is this real and under which license it is. I wouldn't wanna have all my work GPL'd or copylefted.

You didn't answer me this:

http://www.ebay.com/itm/ESP-32S-ESP32-D ... Swax5Y1OV3

Is this a good item? I'm definitely buying an ESP32. However, I'm wondering if there is a board like this on eBay with a Li-Po battery charger. I saw one, but it has a weird case for a battery that looks like those old normal remote control batteries, but I'm not sure. I don't know where to find those batteries. I'm looking for some kind of batteries like the one for MAKERbuino as well as a Li-Po battery charger for that.
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Re: Need help in buying a display for Teensy 3.6

Postby awesome101 » Thu Jun 15, 2017 8:22 pm

The board on ebay is fine. I don't know how to power it though
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Re: Need help in buying a display for Teensy 3.6

Postby Zvoc47 » Fri Jun 16, 2017 4:07 pm

What is special about this ESP32S? What's the S for? Does it have two cores and a MMU and all that stuff?
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Re: Need help in buying a display for Teensy 3.6

Postby awesome101 » Fri Jun 16, 2017 5:38 pm

There's nothing really special about it besides the fact that it's really powerful. The best part is that it's much cheaper compared to the Teensy 3.6 which is 36$ USD
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