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Topic: Questions on making a minimal/custom Arduino circuit @ 3.3v/8Mhz? (Read 3 times) previous topic - next topic


Lithium coin cells are usually 3.6 volts, not 3.0.

that's wrong.   You can find Li-ion coin cells with a "nominal" 3.6V or 3.7V, but the vast majority of non-rechargable Li coin cells are 3.0V  http://www.duracell.com/media/en-US/pdf/gtcl/Product_Data_Sheet/NA_DATASHEETS/CR2032_US.pdf


this can not (should not) be a chip by itself project... IMHO.. 

I mean I need it to be small.. but I want it to work and be somewhat stable!  lol

The chip-only implement will work and will be very stable.


update: well..  i got things up and running with a minimal/breadboard Arduino using +3.3v @ 8MHz internal clock

to be clear order of things (for me) were:

1.) hook up my Arduino Duemilanove 2009 board to USB
2.) Open IDE (I used v.23)
3.) Tools >>> Board >> (Duemilanove 2009)
4.) Tools >>> Serial Port  (select port your above Arduino is connected to)
5.) File >>> Examples >>> ArduinoISP..  (upload this sketch to your Arduino board.
6.) Disconnect.. from USB
7.) Connect a 100-120 ohm resistor between RESET & +5v (to disable auto-reset on the MAIN board)
8.) Connect your target board (minimal +3.3v/8Mhz internal clock) to the MAIN Arduino above.

Wiring Pnout:
Arduino board pin   >>>  Target board pin
               D10       >>>>           RESET
               D11       >>>>           D11
               D12       >>>>           D12
               D13       >>>>           D13
               GND      >>>>           GND
               +3.3v     >>>>           VIN on breadboard...

9.) Reconnect MAIN Arduino board to USB.
10.) Open IDE (I used v.23)
11.) Tools >>> Board >> (Breadboard 3.3v with Internal 8MHz clock)
12.) Tools >>> Serial Port  (select port your above Arduino is connected to)
13.) Tools >>> Burn Bootloader >> w/Arduino as ISP

(bootloaded and can upload sketches all day...)..

two things I noticed though...

1.) Does NOT work with Aruino IDE 1.0+ out of the box...not sure exactly how to make it work yet either.

From reading around, it seems to have something to do with:
a.) editing/adding pin_arduino.h or Arduino.h files to somewhere.
b.) edit the breadboard  'boards.txt' file.. and add a line at the end?

(not to sure.. a bit above my comfort level messign with boards.txt and stuff)

this is just specific to my project.. not about the minimal Arduino part..


2.) and the MAIN problem I need to overcome..   I cant seem to communicate/initialize an SD card???
Using an Arduino @ 16MHz (external crystal) & +5v... I have never had a problem.. with voltage divider or level shifter..or shield...

having the Arduino with +3.3v logic and INTENRAL 8MHz clock doesnt seem to work.. and I 'thought' I would be able to directly connect/communicate to it? (no voltage divider, no level shifter..etc)

been searching around.. and havent found much on using 3.3v8MHz internal clock -with- SD card..

anyone done this? (so I know Im not spinning my wheels?)


Lets see the schematic you said you'd post back in #15 & #18, and your sketch.

How'd you bootload it?
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.


(sorry thought I had posted it)..

I ran into this post while searching here on the topic.. and just updated the outcome..

I started a thread about 3.3v/8MHz Internal clock and SD card communication thread here:


I have that circuit mocked-up on a breadboard right now.. before I order PCBs and make it all SMD..

this is the SAME project.. that we discussed via PM.. (ultra tiny pcb with zero space to work with & custom pcb shape/outline)

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