Pages: [1] 2   Go Down
Author Topic: Help making bare minimum standalone arduino.  (Read 6205 times)
0 Members and 1 Guest are viewing this topic.
0
Offline Offline
Full Member
***
Karma: 2
Posts: 100
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

So a long time ago, I had stumbled upon instructions for making the absolute bare minimum arduino, using nothing more than the atmega chip (with your sketch pre-uploaded), a 16mhz crystal, 5v regulator, and a couple capacitors or resistors.  In fact, I remember you could even omit the crystal (suffering a slight loss in timing, but functional for most things where timing isn't super important), and I'm pretty sure you could even ditch the 5v regulator too, as long as you were powering it by batteries that were roughly 5 volts.  Making it little more than just the plain chip itself, and maybe a resistor or two.

However I've been searching all over the place, and can't find the details how to do this anymore.  Searching for standalone arduino, or bare minimum arduino gets hundereds of results, that are far from what I'd call bare minimum.  Can anyone point me in the right direction for some good instructions on how to use the absolute bare minimum with only the chip, crystal, and regulator w/ caps (and also without the crystal and regulator).

Also one other question, what is the safe range of voltage you can power arduino from without using a regulator?  Like is 6v from 4 aa batteries fine?  What about 4.8v from 4 rechargeable AA batteries?
Logged

Lancashire, UK
Offline Offline
Edison Member
*
Karma: 9
Posts: 1991
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

You could do a lot worse than looking at the instructions and schematic of the RBBB for a minimalist Arduino :

http://shop.moderndevice.com/products/rbbb-kit
Logged


Colorado
Offline Offline
Full Member
***
Karma: 2
Posts: 220
Arduino 0022 and Ubuntu 11.10 64bit.
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset


http://www.arduino.cc/en/Main/Standalone
Logged

0
Offline Offline
Shannon Member
****
Karma: 206
Posts: 12113
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
Also one other question, what is the safe range of voltage you can power arduino from without using a regulator?  Like is 6v from 4 aa batteries fine?  What about 4.8v from 4 rechargeable AA batteries?

The ATmega328 datasheet is your reference here (all 20MB of it!) but I think the 328P does 1.8V upto 5.5V.  HOWEVER you won't get an Arduino-bootloaded chip to work as low as 1.8V without reprogramming the fuses to reset the low-voltage brown-out detector threshold and the clock options to work with a much slower crystal.  So the practical limits are about 3V (with 8MHz clock) upto 5.5V abs. max (16MHz).   

6V is too much (although a battery-polarity-protection diode will drop enough voltage to help work with 6V battery).  NiMH rechargable batteries are 1.3V, not 1.2V, contrary to popular belief, and 4 fully charged NiMH's provide a nice 5.4V or so (convenient).  4 NiCd's give 4.8V which will work nicely.  Lithium cells are 3 to 3.7V and probably need the slower 8MHz crystal (some people report using the chip at 3.3V and
16MHz but that's outside the specifications.)

Note that the accuracy of analog->digital conversion depends on the accuracy of the supply voltage, so working without a regulator will be a big issue if calling analogRead().
Logged

[ I won't respond to messages, use the forum please ]

Chile
Offline Offline
Edison Member
*
Karma: 35
Posts: 1251
Arduino rocks?
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

This is my minimum approach!

(I am using the atmega8 firmware... so it runs at 8 mhz but without an external oscilator, just an stable 3.3v power and the reset button)
Logged

My website: http://ried.cl

0
Offline Offline
Full Member
***
Karma: 2
Posts: 100
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Thanks for the help so far.  I've looked at those sources, and they still seem to be have more components than necessary for a bare minimum setup.  They did help though, I think i might have been able to figure it out, and I made a crude schematic. Does it all look correct and problem free?

http://img191.imageshack.us/i/arduinoschematic.jpg/

I've seen different places use either 20pf or 22pf capacitors on the crystal, does it make a difference?


Also as far as if a voltage regulator is desired, well I bought the 3 parts that were mentioned in the arduino reference
    * 7805 Voltage Regulator Jameco# 51263
    * 10μF Electrolytic Capacitor Jameco# 94220
    * 1μF Electrolytic Capacitor Jameco# 94160
However I have been unable to find a simple schematic for this part, trying to do a search results in multiple different schematics, all containing more than just those 3 parts (such as diodes, extra capacitors, etc).  Can anyone explain, or point me in the right direction how to make the voltage regulator with those 3 parts only?
« Last Edit: February 18, 2011, 12:27:58 pm by carl1864 » Logged

Left Coast, CA (USA)
Offline Offline
Brattain Member
*****
Karma: 361
Posts: 17293
Measurement changes behavior
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset




Here is quick overview of wiring up a 7805 type regulator. Wire the larger of your two caps to the input and the smaller to the output. The actual values of the caps is not too critical, but without any input and output caps your regulator will tend to break out into oscillation.

http://electronics.howstuffworks.com/digital-electronics4.htm
Logged

Lancashire, UK
Offline Offline
Edison Member
*
Karma: 9
Posts: 1991
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

The arduino reference uses 2 10uF capacitors with the 7805.  They are laid out as the RBBB schematic without the resistor led and diode.  The 47uF capacitors on the RBBB are probably better values to allow for more current capability and a less well behaved power source..  You want some decoupling capacitors (.01 uF ceramic work well) between GND & VCC close to the ATmega on your own schematic.  It would work without (probably) providing you're not connecting anything to the Atmega chip. (Kind of defeats the object).  If you have plans to connect anything remotely electrically noisy you may well need more decoupling above the 2 .01 uF capacitors. 
Logged


0
Offline Offline
Newbie
*
Karma: 2
Posts: 42
Instant Karma
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

To be picky (but not disrespectful, I hope) you are not making a standalone Arduino. You are making a standalone microprocessor. You won't be able to do anything with it until you connect it to the outside world. But that is also true of any Arduino unless you just want to see a LED flashing. At some point you may need to reprogram the chip so I would suggest you use a header in your project. Your schematic looks OK, but you will probably find it easier to get 22pF caps, as they are standard values, where 20pF are not AFAIK. Anyway, good luck.
Logged

Venezuela
Offline Offline
Jr. Member
**
Karma: 2
Posts: 81
The less You explain, the more I understand
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset


http://electronics.howstuffworks.com/digital-electronics4.htm
This could confuse. A transformer doesn´t have polarity ( + or - ).
A rectifier does. The schematic should read "+ from rectifier OR battery , - from rectifier 0R battery" . You can use a 9 or 12 volt battery.

 
 
 
Logged

0
Offline Offline
Edison Member
*
Karma: 7
Posts: 1243
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

My thread covers this same exact thing.. (with some trouble shooting) that Lefty already pointed out in here and helped me..

http://arduino.cc/forum/index.php/topic,52707.0.html

to keep things even cheaper..

1.) buy Ateml chips pre-loaded with bootloader (unless you have a real/true Arduino around to flash).. keeps cost down

2.) to keep cost down even more.. use one of the tuts outlining how to use an old cell phone data cable as an FTDI cable to upload sketches to your Arduino circuit.

Logged


0
Offline Offline
Full Member
***
Karma: 2
Posts: 100
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Thanks for those diagrams of the voltage regulator.  I'm still getting 2 different stories about the capacitor sizes though, I had copied and pasted from the reference and it said a 10uf and 1uf, and "retrolefty" mentions a big and small cap, but "pluggy" said he read in the reference somewhere that its 2 10uf ones, I've also heard other sources seemingly using 2 identical ones.  Does it work both ways, or is one method better?

Also, voltage regulator aside, does the schematic I posted above look all correct and problem free?

As far as the issue "selby96" mentioned about programming it.  Well I plan to just program it with a duemilanove board, and then take it out and put it in its permanent spot in its own circuit.  The purpose of me making the minimum standalone is for permanent installation.  I do all the prototyping on the duemilanove board, but once a project is done and needs no more changes, I'd like to just pop the chip out, install it permanently to the project, and pop a fresh atmega328 with bootloader into the duemilanove and move to the next project.
Logged

Left Coast, CA (USA)
Offline Offline
Brattain Member
*****
Karma: 361
Posts: 17293
Measurement changes behavior
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
Thanks for those diagrams of the voltage regulator.  I'm still getting 2 different stories about the capacitor sizes though, I had copied and pasted from the reference and it said a 10uf and 1uf, and "retrolefty" mentions a big and small cap, but "pluggy" said he read in the reference somewhere that its 2 10uf ones, I've also heard other sources seemingly using 2 identical ones.  Does it work both ways, or is one method better?



The capacitor sizes for the regulator input and output are very non-critical. However, rather then expecting someone on the web to give you the 'perfect & exact' (or even a correct answer for that matter), you should do what most of us do, get a copy of the chip's datasheet and see what it says and recommends. That is always the reference one should go by.

 Here is a link to the original national LM7805 fixed +5vdc regulator. On the very first page there is a picture showing input and output caps with notes about there usage. That input cap is shown as .22ufd, but larger is fine. The output cap is shown as not required, but .1ufd suggested. For use with digital components like the 328 chip, It's common practice to wire .1ufd caps between +5vdc and ground at various spots on your board, best location being right at the +5vdc power pins for your AVR chip, pins 20 & 22. Digital circuits create noise on the +5vdc power bus and power bypass caps are your best friend to help prevent strange problems.

http://www.national.com/ds/LM/LM340.pdf

Logged

Offline Offline
Jr. Member
**
Karma: 1
Posts: 54
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I know that others have posted the usual (and very good) how-to's, but just thought I would pitch this one in just to throw in the bucket. It's the most thorough one I have seen thus far (but it's on a breadboard, but it's easier to see the concepts by this)

http://itp.nyu.edu/physcomp/Tutorials/ArduinoBreadboard

BTW, FTW -
http://www.adafruit.com/adablog/wp-content/uploads/2009/05/one-chip-arduino-v2-0.jpg[/img]]http://arpro.posterous.com/one-chip-arduino

Logged

Lancashire, UK
Offline Offline
Edison Member
*
Karma: 9
Posts: 1991
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Capacitors in many (most ?) applications are very non critical.  The reference I was looking at for the 2 10uF capacitors around the 7805 is http://www.arduino.cc/en/Main/Standalone
If your power supply isn't particularly clean bigger is often better.   In my opinion any simpler than the RBBB is too far, you soon get sick of swapping chips when you're debugging sketches and the simple programming interface and reset switch makes life bearable. 
Logged


Pages: [1] 2   Go Up
Jump to: