Ardunio on a PCB

Hello all, I am off working on a new project and have a couple of questions! I am trying to work with a bare bones Arduino (atmega328).

  1. Does AREF need to be pulled to 5v?

  2. Does AVCC need to be pulled to 5v?

  3. Can the 22pf caps for the 16mhz crystal be "Multilayer Ceramic Capacitors"?

  4. Can the caps for a 5v regulator also be "Multilayer Ceramic Capacitors"?

As a side note light-dependent resistors. So nothing that needs to be really "spot on" for the analog reads.

Thanks in advance for any help.

  1. Does AREF need to be pulled to 5v?

Do you need AREF? Does it make sense if the analog reference is at 5V?

  1. Does AVCC need to be pulled to 5v?

If you need the internal ADC, yes.

  1. Can the 22pf caps for the 16mhz crystal be "Multilayer Ceramic Capacitors"?

Yes.

  1. Can the caps for a 5v regulator also be "Multilayer Ceramic Capacitors"?

Depends on the used components. Usually it's a combination of ceramic and electrolytic capacitors.

As a side note light-dependent resistors.

I don't understand this sentence. Is that a question? Should it be a description of your application?

You can google “ minimal Arduino” for some circuits.

pylon: Do you need AREF? Does it make sense if the analog reference is at 5V?

Thank you for the info. Makes sense just never used that header on an Uno or Mega. Must be connected internally on the board.

pylon: If you need the internal ADC, yes.

This is what I thought but wanted to make sure.

pylon: Yes.

Wanted to know so I can use small components and SMDs at that.

pylon: Depends on the used components. Usually, it's a combination of ceramic and electrolytic capacitors.

What do you mean a combination of ceramic and electrolytic? I have seen people use electrolytic on the input and output to help smooth it out. This is the part i plan on using for the 5v regulator. https://www.mouser.com/ProductDetail/511-L7805CV

pylon: I don't understand this sentence. Is that a question? Should it be a description of your application?

Sorry about that. I was a little tired when writing the post. I meant to say I will be using a couple of Light-dependent resistors. didn't know if that would make a the on the AREF question.

Thank you for the info. Makes sense just never used that header on an Uno or Mega. Must be connected internally on the board.

No - you have that all wrong - read the data sheet!

Mark

holmes4: No - you have that all wrong - read the datasheet!

What part? I am still learning this type of stuff. Reading data sheets are still a lot of bit confusing. I am slowing learning how but not there yet. I have read other places that say yes it needs to be connected and other places it does not. Very confused.

  1. Does AREF need to be pulled to 5v? No, it is connected via multiplexer in the chip. Only connect a 0.1uF cap to Gnd.

  2. Does AVCC need to be pulled to 5v? Yes, always.

  3. Can the 22pf caps for the 16mhz crystal be "Multilayer Ceramic Capacitors"? Thruhole, can be any part like this https://www.digikey.com/products/en/capacitors/ceramic-capacitors/60?k=22pf&k=&pkeyword=22pf&sv=0&pv14=32&sf=1&FV=ffe0003c%2C1140050&quantity=&ColumnSort=0&page=1&stock=1&pageSize=25 SMD, like this https://www.digikey.com/products/en/capacitors/ceramic-capacitors/60?k=22pf&k=&pkeyword=22pf&sv=0&pv2049=u22pF&pv69=453&sf=1&FV=ffe0003c&quantity=&ColumnSort=0&page=1&stock=1&pageSize=25

  4. Can the caps for a 5v regulator also be "Multilayer Ceramic Capacitors"? Caps should be aluminum electrolytic. 10uF on input and 1uF on output usually work well.

Be sure to put 0.1uF on Each VCC, AVCC pin.

Just buy a Pro Micro or Teensy and solder it down to your board. Use the Arduino as a module and don’t try to redesign it.

CrossRoads - Something like the schematic I have attached

MorganS: Just buy a Pro Micro or Teensy and solder it down to your board. Use the Arduino as a module and don't try to redesign it.

This may be what I end up what do but I am trying to learn. Even I don't use the chip by its self on this project I could always use the knowledge on a future project.

Gidget19893161: CrossRoads - Something like the schematic I have attached

That kind of label diagram is a pain to have to decipher, but it looks like you're missing the decoupling capacitors .

BJHenry: That kind of label diagram is a pain to have to decipher, but it looks like you're missing the decoupling capacitors .

On the 5v regulator?

Gidget19893161: On the 5v regulator?

On the ATMega328 IC itself. You need to have a 100nF capacitor on each VCC and AVCC pin.

BJHenry: On the ATMega328 IC itself. You need to have a 100nF capacitor on each VCC and AVCC pin.

Does it need to go to GND?

Gidget19893161: Does it need to go to GND?

If you ask that question I really think you need to just purchase Pro Minis and mount them as daughter-boards to any PCB you make. Easier, cheaper, more reliable. :sunglasses:

There are projects around such as making a simple microcomputer from logic ICs. Supposedly they could help you learn about microcomputers. In fact, it's more like the famous "peeing in your wet-suit" allegory. "Building your own" Arduino is in the same category. :roll_eyes: