Arduino layout P2 board? (It Works! Eagle design files posted).

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Comments

  • jmgjmg Posts: 14,539
    Tubular wrote: »
    I wonder what the current rating on P2 pins in reverse bias is? 500uA like the P1? 1mA?

    The clamping is a reverse P-FET substrate diode, so it will present a hard clamp if attempted to push to 5V.
    A typical 5V-CMOS output load line would drive 20-30mA into each clamped pin, and one risk is that reverse current then elevates the 3v3 rail (eg if P2 is reset) and so damages P2.

    I wonder if using a DDR regulator on a design that might encounter 5V-Driving logic is worthwhile ?
    Parts like RT9045 or RT9173 would keep a 3.3v rail at 3.3v

  • I used bypassible current limiting resistors on the ASC to keep those clamping diodes from frying on 5 volts. For this board though I think it'd be too much. People will just have to use their smarts and accepting of a modicum of responsibility for connecting over voltage inputs. Just like they do for hundreds of other boards, including 3.3v arduinos.
  • It’s alive!
  • Sweet!
  • Wow! That was amazingly fast from idea to functional board!

    Great job!

  • Good work Rayman. You don't muck about. It's good to see an interesting range of P2 boards being made now.
  • RaymanRayman Posts: 11,482
    edited 2020-11-20 - 22:26:58
    The advantage of starting from another known good design is speed.

    Downside is not all the P2 pins going to headers. Still bummed about that, but at least could bring two of them to LEDs and some of the others to probe points.

    1499 x 1633 - 315K
  • Hey Ray are you still using ExpressPCB? I was looking at their site the other day for first time in years, they've evolved a bit

    Board looks good
  • I used them for a long time, but finally switched to Eagle a few years ago...
  • Going to see if I can get it to work with this LCD module from Amazon...

    https://www.amazon.com/gp/product/B01EUVJYME/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
    3024 x 4032 - 2M
  • Martin HodgeMartin Hodge Posts: 1,245
    edited 2020-11-21 - 02:55:49
    Rayman wrote: »
    The advantage of starting from another known good design is speed.

    Downside is not all the P2 pins going to headers. Still bummed about that, but at least could bring two of them to LEDs and some of the others to probe points.

    You could add 8 more pins to the bottom of the ICSP header like I did on the ASC. (A added 10, but the bottom 2 went to analog inputs on the adc chip)
    https://1mgh.com/wiki/Asc#Add-on_cards
  • @Martin Hodge
    Maybe you're the right person to make this kind of board?
    I see a lot of Arduino stuff on your website...
  • I posted the design files to top post, in case somebody wants to make there own, or hopefully improve it.
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