Shop OBEX P1 Docs P2 Docs Learn Events
P2 Edge Module Breadboard specifications — Parallax Forums

P2 Edge Module Breadboard specifications

PrebenPreben Posts: 15
in Propeller 2

I looked for the electrical specifications for the Breadboard Module, but all I could find was a statement saying that the max. mA per group of 8 pins is 300mA.

But what is it per pin if I only use 1 pin out of the group of 8 pins? 300/8 mA?

I'm looking to program a basic LED setup on a breadboard with a 20mA current draw, and I want to ensure the device remains intact.

I was also wondering how to get + and - onto the 4 Breadboard blocks, already marked with + and -. Do I need to "jumper" them?

Thanks

Preben

Comments

  • evanhevanh Posts: 16,023
    edited 2024-12-03 21:14

    Usually 5 mA is good for most indicator LEDs. You don't want to be cooking them either.
    The Prop2 datasheet says absolute max 30 mA per pin. https://www.parallax.com/propeller-2/documentation/

    PS: The default FAST pin drive strength is around 20 ohms. So, at 30 mA, that is 0.6 V and 18 mW of loss.

  • RaymanRayman Posts: 14,744
    edited 2024-12-03 22:45

    Think there's also a 120 mA max for every group of 4 pins.

    But, the edge has 1 LDO regulator for every 8 pins, with a max of 500 mA. That's probably the source of the 300 mA limit...
    That plus 120 times 2 is 240 mA...

    So, there's limits per pin, per group of four, and per group of however many are connected to the regulator...

  • RaymanRayman Posts: 14,744

    Still, actual limit for 8 pins has to be 240 mA, by the datasheet.
    Doesn't matter if sourcing or sinking, it's 30 mA per pin...

  • TubularTubular Posts: 4,705

    Preben you'll be absolutely fine at up to 30mA, we've done testing beyond that and never had a failure yet

    @Rayman said:
    Still, actual limit for 8 pins has to be 240 mA, by the datasheet.
    Doesn't matter if sourcing or sinking, it's 30 mA per pin...

    I've been looking into this and it seems the Vss connection to the 4 pin group is much stronger (lower resistance) than the 3v3 connection, which perhaps comes via a longer gold wire bond. Thats what I'm thinking, it would be good to confirm with Chip.

  • PrebenPreben Posts: 15

    I will soon start playing around and will have more questions for you.

    I do try searching and may find answers in previous posts before asking questions.

    Thanks all!

    Preben

Sign In or Register to comment.