How much load can I connect to FEZ Spider?

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1

How much load can I connect to the FEZ spider?

I plan to connect multiple LEDs (say 40 / multiplexed) - can I connect them directly or do I need an additional driver circuit?

2

4mA is recommended, that is one LED.

3

Are you asking how much through the 5V source pin or how much through an output pin? I think Gus was replying to to how much through an output pin and I also believe he meant to say 40mA instead of 4mA :wink: You can power many more through the 5V line but you’ll need to switch them using transistors via the output pin. You don’t mention a module so I assume you’re talking about natively using an Extender.

4

Thanks!

Is there a total amount of load for the whole board or can I connect 40mA to every pin?

First, I want to experiment with a breadboard and then maybe develop a module…

What I want is to connect as many lighted buttons as possible to a gadgeteer socket. The application I have in mind is a MIDI sequencer based on Pete Brown’s great module . When I use a multiplexer I would need to use the 5V output, right?

5

Actually that was 4ma not 40.

All pins exposed are meant for signals or small LEDs. You should add circuitry to wire your lights, or simply use maxo module. See it on catalog please.

6

I think MaxO is exactly what I am looking for!

So, when I have two MaxO modules, I can connect 32 lighted buttons to a single gadgeteer socket? (each lighted button having an input for the LED and an output for the button?)

7

MaxO as the name states, O = Output, so you won’t be able to read your buttons.
To read your buttons you’ll need IO60P16 Module

8

So many great new modules :wink:

Just to be sure: with one IO60P16, I can connect 30 lighted buttons, right?

9

Yes :slight_smile: I am assuming little LEDs. You should check the chip used on that board for exact limitations.

10

Alright, thank you all!

11

What can I do if I want to connect LEDs which require 20mA current? (50mA peak current)

I would like to connect about 30 of these: http://www.nkkswitches.com/pdf/NP01.pdf

12

Use load module or maxo module

13

Hmm, MaxO has only 10mA per pin and 5 load modules is a complicated and expensive solution.

14

DIY then?

15

I am afraid so :wink:

I hoped there was a standard solution, since I have almost no experience in hardware stuff…

16

Cheap vs off-the-shelf. Welcome to the world of “I have specific needs and want something cost effective”… unfortunately the hidden costs - not just your time but the other tinker costs - still add up and look somewhat messy…

Sounds like you might need to look into LED drivers and shift registers or similar… or maybe you can use the MaxO and a LED Driver chip (or even just a bunch of transistors)

17

Above all, I want a good and simple solution - I does not necessarily have to be cheap.

“LED driver” sounds like the thing I need!

Thanks!