Forum Rule: Always post complete source code & details to reproduce any issue!
Page 7 of 7 FirstFirst ... 5 6 7
Results 151 to 165 of 165

Thread: VGA out for Teensy 4.0/4.1

  1. #151
    Member
    Join Date
    Aug 2020
    Location
    France
    Posts
    83
    Are the resistor values for 12 Bit the same for the R2R?
    Yes Frank , the resistor value are the same when you add more stage ( 1 x 536 and 1 x 270 ohm ).
    Just bad that i cant help for the VGA code on Teensy , i was more involved in STM32 in the past , and the registers / DMA etc used on teensy are actually black magic up i can learn more on this MCU

  2. #152
    Senior Member+ Frank B's Avatar
    Join Date
    Apr 2014
    Location
    Germany
    Posts
    8,338
    Does this look OK?
    Click image for larger version. 

Name:	T4VGA.jpg 
Views:	59 
Size:	103.1 KB 
ID:	23754

  3. #153
    Senior Member+ Frank B's Avatar
    Join Date
    Apr 2014
    Location
    Germany
    Posts
    8,338
    Are you aware of the VLSI23S010D ?
    This is a 1MBIT SPI memory with integrated DACS for video. It can do PAL, NTSC (and I think VGA) - LQFP48 (would have to practice soldering...)

    There is also a successor, with 4MBIt and higher resolutions. Unfortunately it is a BGA.

    But with a chip it's not so much fun...

  4. #154
    Senior Member
    Join Date
    May 2018
    Posts
    211
    for the emulators you need the PSRAM soldered on the T4.1 and of course the analog joystick + the 3 buttons. See IOPIN.h, should be also on the schematic of the MCUME project.
    This is the min config (some emus don't need the PSRAM)

    USB can also be added for the computers (not all, mostly ST and Amiga). I2C keyboard for computer keyboard is optional.

  5. #155
    Senior Member+ Frank B's Avatar
    Join Date
    Apr 2014
    Location
    Germany
    Posts
    8,338
    Quote Originally Posted by Jean-Marc View Post
    for the emulators you need the PSRAM soldered on the T4.1 and of course the analog joystick + the 3 buttons. See IOPIN.h, should be also on the schematic of the MCUME project.
    This is the min config (some emus don't need the PSRAM)

    USB can also be added for the computers (not all, mostly ST and Amiga). I2C keyboard for computer keyboard is optional.
    Thanks
    What do you think?
    Click image for larger version. 

Name:	5b6fae2649a4ab87d8fb6c90f9cd5734.jpg 
Views:	52 
Size:	115.0 KB 
ID:	23766

    - The analog joystick + Fire is on a extra connector.
    - 3 Buttons "on board"
    - C64 Joystick connector,
    - Big connector is for all signals but VGA + I2S

    Schmatic attached
    Attached Files Attached Files

  6. #156
    Senior Member+ Frank B's Avatar
    Join Date
    Apr 2014
    Location
    Germany
    Posts
    8,338
    Ok, corrected the name to MCUME added an I2C connector, and ordered 5pcs ...
    Thanks. I'll stop polluting this thread now

  7. #157
    Senior Member
    Join Date
    May 2018
    Posts
    211
    Looking great!
    You went for the full ladder of resistors which is not a bad thing.
    So you directly used the I2S audio chip directly on the PCB, I never went that far (I used the module from amazon)... ;-)
    Most important is VGA and audio. Buttons can be remapped in SW

    I will just miss a fixed USB connector on the PCB but for the rest it looks ok. I never found a proper way to connect USB host to the teensy with a floating wires...

    Having the full header on the side is a great idea.
    I was looking for a way to support both ILI display or VGA with the same PCB but the issue will be the resistors on the SPI. But not if we use the SPI bus on 39,26,27 + another pin for CS via the full header connector.

    Thanks a lot for the contribution.
    You know that I am not a HW guy, my PCB will never be that nice!

  8. #158
    Senior Member+ Frank B's Avatar
    Join Date
    Apr 2014
    Location
    Germany
    Posts
    8,338
    I'm not a hardware-guy, too. And I have not enough practice with creating PCBs.. maybe I do 3 different in a year.. and.. 70% of the first run have a mistake somewhere!
    But from china, that's not a big problem.. paid around 7.50€ now (PCBs in nice blue - not the color above)
    If it turns out to work (I hope so..well..30% chance , I want to send you one (with parts). Another goes to BriComp, and I'll use the remaining three.
    USB: PJRC sells a cable for that. And I once made a "daughter board" - very small - that can be soldered on top of the Teensy. It was made for the 3.6, so it's above the ethernet, unfortunately.

    Edit: Turns out that my prefered shop does not sell 536Ohm in small quantities .. grrr..$%&/ I don't need 5000pcs..

  9. #159
    Member
    Join Date
    Aug 2020
    Location
    France
    Posts
    83
    I grab close to everything from Farnell Element 14 ... here the french page with 536 ohm , you can get all quantity you want
    https://fr.farnell.com/w/search/prl/...ats?st=536+ohm

    But bigger quantity is better as on all other places

  10. #160
    Senior Member+ Frank B's Avatar
    Join Date
    Apr 2014
    Location
    Germany
    Posts
    8,338
    LoL, yes, but 5000 is a bit too much.
    Thanks for the hint with Farnell. I think I'll order there.

  11. #161
    Senior Member
    Join Date
    May 2018
    Posts
    211
    You are also from Germany I think, I am from Brussels.
    I typically order from Mouser but I was lucky to have a small electronic shop nearby selling parts.
    He just retired 2 months ago unfortunately...

    I have not been very active the past months on the Teensy.
    I wanted to upgrade some of my old computers...
    After 35 years, I decided to upgrade my own Atari520ST with a Terriblefire534 and extra memory.
    Those boards are made to replace 68000 on Amiga but I ended up on the Atari forum with a guy using them on Atari.
    I am still struggling with some compatibility issue but it basically runs with the IDE CF. It is amazing to see an ST with a 68030 at 50MHz.

    I was thinking about using the Teensy 4.1 on real C64. There was that Backbit project using T3.5. May be we could add VGA output to a real C64 and simulate the VIC chip?

  12. #162
    Senior Member+ Frank B's Avatar
    Join Date
    Apr 2014
    Location
    Germany
    Posts
    8,338
    Quote Originally Posted by Jean-Marc View Post
    You are also from Germany I think, I am from Brussels.
    I typically order from Mouser but I was lucky to have a small electronic shop nearby selling parts.
    He just retired 2 months ago unfortunately...

    I have not been very active the past months on the Teensy.
    I wanted to upgrade some of my old computers...
    After 35 years, I decided to upgrade my own Atari520ST with a Terriblefire534 and extra memory.
    Those boards are made to replace 68000 on Amiga but I ended up on the Atari forum with a guy using them on Atari.
    I am still struggling with some compatibility issue but it basically runs with the IDE CF. It is amazing to see an ST with a 68030 at 50MHz.

    I was thinking about using the Teensy 4.1 on real C64. There was that Backbit project using T3.5. May be we could add VGA output to a real C64 and simulate the VIC chip?
    Yes.. things like these are fun.
    But for me, it's not that interesting. In addition, the VIC is very tricky. It has to be cycle-excact to be 100% compatible - I have it working in the emulaton, but for 3.6 I had to do a few tradeoffs. Some Demos are not working. The VIC code would have to be rewritten...
    It is very tricky, too... the Commodore engeneers did a totally amazing, unbelievable job. Decades later users still found new ways to use it for new effects. With 1MHZ system clock...

    I like more to just use the grey "bread" housing, with the keyboard...

  13. #163
    Senior Member+ Frank B's Avatar
    Join Date
    Apr 2014
    Location
    Germany
    Posts
    8,338
    Arrived
    Click image for larger version. 

Name:	20210311_180035.jpg 
Views:	54 
Size:	130.9 KB 
ID:	24020
    The colors are quite good, sound too. As you see I added USB:
    Click image for larger version. 

Name:	20210311_183047.jpg 
Views:	47 
Size:	201.4 KB 
ID:	24021
    Well.. the USB connection is very near to the VGA :-(
    A few vias are too near to pads. Needs a bit attention when soldering.
    As said.. most of my boards have issues If I ever do a second version i'll fix that (and I need to create a "checklist" with these isues listed, to make my next boards better). Perhaps a 2nd USB to power the VGA->HDMI converter would be useful, too.


    So far, only VGA and Sound is tested. There's a simple lowpass after the chip. As I bought some PT8211 clones "TM8211" several years ago, and have never tested them, I tried it here. For my ears, it's pretty equal.
    As I'm not an "audiophile" I have no plans to test the soundquality further.

    Click image for larger version. 

Name:	20210311_183253.jpg 
Views:	39 
Size:	214.3 KB 
ID:	24022

  14. #164
    Senior Member
    Join Date
    May 2018
    Posts
    211
    Looking great!
    Can you still fit a VGA cable with a USB mouse/keyboard like dongle next to it ?
    I typically have a small passive HUB attached so should be ok (just like the USB connector width)
    Have you tested Audio using the interrupt based Audio driver of the VGA library?

    if you use a VGA2HDMI adapter may be not a bad idea to power it via an extra USB port but will the power be enough if you for e.g. connect other stuff via the header pins.

    Not bad for a first design.
    I like the fact you have all connectors (but the joystick) at the back.

    I also like the SMD pinch on the picture, you had fun soldering the resistors ;-)

  15. #165
    Senior Member+ Frank B's Avatar
    Join Date
    Apr 2014
    Location
    Germany
    Posts
    8,338
    My eyes are not the best. Farnell did not want to send to me (only to companies), but I found TME.eu sells 536R - but as 0603 only. Soldering them was a bit tricky for me - even more as there are two vias very close to a pad :-(
    Most other parts are 0805 - way better.
    When I take a photo with my smartphone and look at the solder joints enlarged, they look terrible - they are almost created in the blind.
    I think I need to get some kind of aid to make soldering small parts work better. Maybe a microscope. $$$ :-(

    USB: A small dongle should fit. Cables with slim connectors, too.
    You have a PM.
    Last edited by Frank B; 03-11-2021 at 09:32 PM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •