Arduino

http://www.instructables.com/id/Make-your-own-Arduino-on-Veroboard/

Try using an lcd with SPI, they're cheap on eBay.

Pro-Mini Notes

Red board, no plastic. Connect to Arduino pro mini with tops of circuit boards facing the same way. Open Arduino IDE as root (or it can't access the serial port). Programmer is "ArduinoISP"

The boards I have are 328P 5v/16MHz. Upload blink and check the timing to figure out if it's 16/8 MHz.

Power is supplied to the Raw pin. Do not connect power directly to Vcc pin. It's supposed to handle up to 12V, but I tried that and the board died very quickly, so don't do that again. Actually, I think I had just above that (12.3v) and 12v is a hard limit. I'm pretty sure the on board regulator is linear, so probably shouldn't give it more than 7V.

For the cheap clones, they go back to back. I think I broke one when I tried to burn a boot loader.

I have two sets of boards, one from sparkfun, one is unbranded. I can get the unbranded ones working. I'm having trouble with the sparkfun ones. It seems like I can upload, but the timing doesn't work right. I can't get serial output. I think the sparkfun boards are 5v 8MHz.

Systems

Power

Step Up

• $2.07 : 3v3 step up
• $0.50 : Battery Clip

Can run off a single AAA battery, good for lightweight.

Step Down

• $0.40 : Battery clips
• $0.43 : Step down regulator

Cheaper, lasts longer. I need to try using just the clips to hold a battery to board. Can also swap out the 4xAAA for a 9V. Lasts even longer, and probably lighter overall.

Display

All options are about $2. The 16x2 is a bit larger and more readable but limited to text. The 5110 is more flexible but kind of small.

Setup

Pro-Mini

$4.62

I really liked these at first, but now that I'm getting a better grasp on the stand-alone circuits, it's not as good. It takes us just as much space as the dip would, the analog inputs are hard to get to.

Stand Alone Tiny85

~$1.50

Limited IO, but that can be expanded with 74HC chips. Good for simple, small projects.

Stand Alone Mega328

~$2.00

Full power Arduino, fairly compact. I think this is the best option.

Setups

• $1.00 : Power; 9v | 4xAAA step down
• $2.00 : Display
• $2.00 : Mega328
• $0.13 : Small Perf Board

$5.13

• $2.50 : Power; AAA step up
• $2.00 : Display
• $2.00 : Mega328
• $0.13 : Small Perf Board

$6.63

STM32

https://circuitdigest.com/microcontroller-projects/getting-started-with-stm32-development-board-stm32f103c8-using-arduino-ide