I put my finger on the atmel atmega 328AU and the serial feedback I got completely ignored the timing delay I put in there, and gave me random feedback. Here is a log of the serial monitor:
31
21
23
22
23
äÅÉŠjRü21 Put my finger on it on this line
dhiÉ5RþrÍþ60 And this one
333
62
81
36
54
155
109
I think I shorted the 16 MHz crystal(temporarily). Why does my finger do this?!
Your body's capacitance changed the frequency of the crystal?
Must have! Only screws stuff up when I touch on the side of the chip connected to the crystal. I just did it again, and this time it STAYED screwed up even after I removed my finger... Weird! Look at this:
36
fá’šjRüoÂ21
22
022ò¸232Zæ˜&¦&&&&8†&¦&–ù’<þ2322â0Ž’’’jŸÒðð23222†0’2²™²ö23222pøH’’iŸÒa23222ò8’’ÉŸÒûhÍÉÉ’’‚ð˜“S~Òû23222âp’šÉÿ²ÿ23222NIk~Òû23222âÀ�’’ÿ²ÿ23222†€$&“ó’ö232222222’™²örgÒÍÒ’’’’’’’Éÿ™&æ€
From 022ò to &æ€ is all one string of stuff, some from after removing my finger.
Does it correct itself if you power down the board for a few seconds?
My recommendation is: Don't touch that that again!
It does. Even pressing reset fixes it.
You are surprised that putting a finger (resistance and capacitance) onto parts of the circuit causes weird effects??
Simple answer is don't do it.
Weedpharma
I'd also recommend not doing it with mains voltages either! Surely its no
surprise that flesh conducts electricity...
Well, body or cloth electricity can destroy any IC today. Discharging yourself on grounded water pipe or wearing protective globs or grounded bracelets (never used) helps.
Sometimes problem is that some input pins are not grounded, thus easily "collect" electricity even fingers are close to it and then interference UART. One of solutions is to pre-define all I/O pins as output or ground all floated input pins.
Use internal pullup on unused input pins also. This keeps the pins from oscillating and can reduce power used when running from batteries.