hey gang.. title says it all..
I have never created/designed a Arduino circuit/board that runs on 3.3v @ 8Mhz before..
I currently have a fun project/challenge that calls for one.. but I want to make sure I understand everything I have read over the months on this subject.. to ensure I havent skipped anything.. or have any unexpected surprises...etc
This custom design/pcb will have uSD socket on it..
Board needs to have minimal design components (space is a HUGE obstacle here), but till somewhat stable
Board will run @ 3.3v
Board will run @ 8Mhz internal clock
Battery solution I 'believe' is a very small coin cell (exact choice hasnt been finalized yet)
1.) If the board is running @ 3.3v/8Mhz (like a pro mini or something).. do I need 'any' sort of level/logic converting for the uSD card then? (whether it be an IC or a simple resistor voltage divider..etc)??
2.) Since the battery used will be more or less a 3.3v (under 5.v for sure, since the only space is really a coin cell type of solution... grrrr)... can I get away with NOT using any sort of voltage regulator?.. and having a few polarized caps along the input/power traces?
3.) being a MINIMAL design is a focal point.. what IS the minimal (but still somewhat stable/safe) components needed?
a.) 10k resistor for reset pin
b.) cap for DTR breakout
*since running @ 3.3v/8Mhz.. I wont need a 16Mhz xstal, no 2 x 22pF caps, no vReg??
Im at a loss? any suggestions to help me plan correctly here?
4.) programming a 'blank' Atmel328 (TQFP) chip to run @ 8Mhz internal clock?
I have programmed blank chips before (both dip and smd) using my Arduino 2009 board, with Arduino as ISP..
I have since moved on to using the Optiloader sketch written my Arduino 2009 board.. and flashed the Opiloader bootloader to my custom/assembled boards..etc..
Everything I have done uses 16Mhz external crystal/caps..
but reading, it seems you need to have the crystal/caps installed/set-up (connected to chip) in order to even WRITE a new 3.3v/8Mhz bootloader? (fuses are set at factory to use external 16Mhz clock?).....
So I could also use some clarification on the easiest way to just flash a bootloader (not even sure which one? pro-mini? lilypad?) that runs @ 3.3v and internal 8Mhz clock..
I have no 'AVR' type programmers, just an Arduino and the IDE..etc..
knowing this.. any suggestions in general? (outside of the specific questions I asked)