I'm fairly new to designing schematics and working with the atmega on its own and I'm designing an arduino schematic on eagle. Ive gotten to the stage where I need to incorporate a TTL USB interface in order to program the chip. I've just became aware that the arduino uses another avr chip to do so but it appears similar to the microcontroller and just need some clarification.
Since I want it all on one board like the arduino uno, my question is how is the USB-B connected to the microcontroller and how would I Incorporate it into my schematic?
Another question (out of curiosity) if I was to mass produce said PCB with one program on the atmega chip and leave out a USB module so people wouldnt be able to reprogram it (without taking the board apart obviously) How would that be done?