Soldering LED SMD & push buttons directly to attiny84 pin ?

[nordi]

Hey,

I'm about to create my very first arduino project: creating a light pattern using 12 LED SMD and push buttons controlled by attiny84.

I was able to find many video tutorials on youtube, and can handle the coding part as well as sending the code into the attiny. However all video tutorials I've been watching so far used either breadboards or PCB circuit to connect the attiny to the LED, which is not possible for my project (I intend on putting these LED SMD into a 2 mm height object). therefore my questions are:

-Can I directly solder the LED SMD wires to the attiny pins ? (or the resistance, although i'm a total newbie, it is my understanding I need to connect the red wire of the LED to a resistor and the resistor to the attiny to prevent the LED to fry and last longer).

-Can I solder more than one LED SMD light to a pin (so one pin would make 2 LED flash with the same pin) ?

Thanks for your help.

[Grumpy_Mike]

Can I directly solder the LED SMD wires to the attiny pins ? (or the resistance, although i'm a total newbie, it is my understanding I need to connect the red wire of the LED to a resistor and the resistor to the attiny to prevent the LED to fry and last longer).

Yes you can but their are two caveats:-
1) Soldering something that small requires a very small tipped iron, a good pair of tweezers and some form of magnification. I use a head loupe. Be aware that the surface tension of molten solder is way stronger than gravity on the part. So you have to restrain the parts mechanically while you solder them or they simply stick to the iron.

2) Once soldered the mechanical strain on the pins could well pull them out and break them, so you would need some form of mechanical backing to fix the parts to.

Can I solder more than one LED SMD light to a pin (so one pin would make 2 LED flash with the same pin)

Yes providing each LED has its own resistor and the combined current it takes is less than the maximum alowable current.

I'm about to create my very first arduino project

It is a big ask for a first project.

[DrAzzy]

https://www.ebay.com/itm/Rapid-Prototyping-LED-Breadboard-for-Arduino-UNO-MEGA2560-NANO-PRO-MCU-LoL-Shiel/282716378548?epid=1631565754&hash=item41d33595b4:g:aH0AAOSw2spbCDC7


No specific endorsement of that vendor (other people sell them too at similar prices) but something like that will make your life so much easier....

I made much the same thing with one of my 1206 x6 mini protoboards and a through-hole bussed resistor network (alas, I'm not home so I don't have pics)

Using SMD parts is very challenging if you aren't making a custom PCB for them; I don't recommend it....

[nordi]

Thanks both of you for your replies, judging from both your posts i might have underestimated the difficulty !
I'm not against using a PCB but sadly my project simply won't allow me to, here is the project with more details:

I have a 1/24 die cast police car to which  I want to add a whelen justice lightbar on the roof (so the height is barely around 1,5 or 2 mm), as well as lights on the headlights, taillights, and grill lights.

I'm more than open on suggestions on the best approach to proceed !

[INTP]

Dead bug is a thing. You just have to be on point with your soldering skills. You are heating up a piece of metal that runs right into your MCU chip. Use an iron that is HOT enough. Hot and quick. Many newbies think they do less damage with a cooler iron but that just means it takes longer to melt solder and in that time frame the heat travels and heats everything nearby.

[tinman13kup]

I think I would mount the smd led's in their location and use enamel coated wire to route them to a pcb mounted in the trunk, or under a seat. The resistors would be mounted on the pcb, and since you are going all out, use some fiberoptic to light up the marker lights.

Even using a dip and through hole resistors, you could probably pack it in a 1" pcb.

[INTP]

A DIP socket would give you some good insurance against your soldering skills as well as from the many ways your chip could end up dead. If that happened, just pull and replace with a new ATTiny.