I am building a custom low-power Arduino board using a SMD ATmega328 and as few components as possible. I have drawn a schematic and want to get some opinions on whether this design looks good. [image] I have used the Gammon website as my base, however I am trying to use a SMD chip rather than a THT chip for space reasons, so I'd like someone to check it. At this point I have a USB as power as I will be powering it using a 5v boost module which has USB output. I would be happier to incorporate the boost module into this circuit if I can, but I need to know if this will work first.

You will need to add the Boot loader to the controller chip before you can use the FTDI. Nicks site shows how to burn the bootloader using the SPI (ICSP) pins. Your circuit looks okay, make sure the crystal is close to the controller pins it connects to, do not run traces in between the crystal leads. Suggest you add a 6 pin ICSP header to the board, at least the possibility of solder one if need be. Decoupling caps need to be close to there pins too. Suggest you just use an Arduino Pro Mini, they have all you need on the board. [image]

[image] LarryD: You will need to add the Boot loader to the controller chip before you can use the FTDI. Yes. I'm going to follow the Gammon site for that! :wink: [image] LarryD: Suggest you add a 6 pin ICSP header to the board, at least the possibility of solder one if need be. Is there a way to upload the bootloader and then solder it to my PCB?? Or is that asking a bit too much?? :face_with_raised_eyebrow:

[image] LarryD: Suggest you just use an Arduino Pro Mini, they have all you need on the board. I need a few more custom capabilities than the pro mini - plus I want the charge circuit and boost circuit on the same PCB

Suggest you use ready built modules (daughter cards) on a Mother board that you design. [image]

Since you sound like this might become a hobby for you, go through this thread, it has ~ 1000 posts of ideas that might tweak some ideas. [image] Share tips you have come across General Electronics This post will contain the index for this thread. This is going to be a work in progress Links to topics will be added so you can select a topic covered (in alphabetical order). Jump Links 123 blocks 44 Button IR remote Advanced electronic videos Alligator clip DIY tool Alligator Clip 3rd Hand to Binder Clip Alligator clip soldering aid tool examples Anti static wrist strap Arduino As ISP Arduino links of interest Arduino protection for pins when bread boarding Battery connector r…

Here is an example of a Mother Board design with a Boost Converter, Pro Min and the capability of an DS3231 RTC. [BoxF] [image] From post [image] Share tips you have come across General Electronics [BoxA.jpg] [BoxB.jpg] [BoxC.jpg] [BoxD.jpg] [BoxG.jpg] [BoxH.jpg] [BoxI.jpg] [BoxE.jpg] [BoxF.jpg]

Here is my schematic of a one-board 5v boost, battery, and MCU: [image] And here is the PCB. Back: [MCUB] Front: [MCUF]

Three things. Unless you have above average soldering skills, a project using a TQFP form factor is not for you. Making your own SMPS can be quite difficult, you need to use the recommended components (avoid substitutions) all recommended component placement is a necessity. ready made boards/modules are inexpensive, less than what you can manage. Suggest you use a boost/buck converter instead of a boost or buck converter. [image] [image] Your vias should be enlarged. Your cross-unders are too long and require return straps.

This is the foil pattern for your LM2621. [image]

[image] LarryD: Unless you have above average soldering skills, a project using a TQFP form factor is not for you. This isn't an issue as the company who is making the PCB offers a cheap guaranteed assembly service which I will be using. [image] LarryD: Making your own SMPS can be quite difficult, you need to use the recommended components (avoid substitutions) all recommended component placement is a necessity. Is this a switched mode power system?? It's just a battery powered device. [image] LarryD: ready made boards/modules are inexpensive, less than what you can manage. That is a fair point actually. This board is going to cost about $35, which is pretty pricey. [image] LarryD: Suggest you use a boost/buck converter instead of a boost or buck converter. I don't want an adjustable output. I want a set 5v output, which is why I used a LM2621. Why do you suggest a boost/buck over this design? [image] LarryD: Your cross-unders are too long and require return straps. I'm not entirely sure what you mean... [image] LarryD: Your vias should be enlarged. I did wonder about that.

Custom MCU using a SMD ATMEGA328

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