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[Reply #30 on:]

For 2¢ you can add several more I/O pins...

Those are nice.  I'm assuming they are programmed in the same way.  That's on my list for next time.

[Reply #31 on:]

ATtiny85s for $1.40 a copy in lots of 10:
http://www.mouser.com/ProductDetail/Atmel/ATtiny85V-10PU/?qs=sGAEpiMZZMvu0Nwh4cA1wUVlLgw9m2DP78s3Ei4lJOM%3d

[Reply #32 on:]

For 2¢ / ATtiny84 ... Those are nice.

I agree.  The analog-to-digital converter has some features that I believe will work very nicely with thermistors; features not available on the ATmega328.

I'm assuming they are programmed in the same way.

Yes.

[Reply #33 on:]

This part?

"programmable gain stage (1x, 20x) for 12 differential ADC channel pairs,"

[Reply #34 on:]

Exactly.  Plus, one pin (I think ADC3) can be used as a common for differential measurements.

[Reply #35 on:]

This is my DIY "arduino", although is little more than a breaduino on a PCB


EDuino

That is cool! - It reminds me a bit of our local hackerspace's own arduino variant, the LCD IO Backpack:
http://www.hackmeister.dk/lcd-io-backpack/

// Per.

[Reply #36 on:]

Hey, good work on that LCD IO Backpack board! So you guys are making workshops around it?
I actually have also an (unpublished) design/prototype for an LCD backpack Arduino-platform based, the main difference being that it was designed to be standalone and provide efficient power to "expansion boards"; it's a bit bigger than the LCD to support a 1A switched buck converter, 3 buttons on the side, a power jack and a simple RS-232 converter - in a single sided PCB you can do at home (4 or 5 jumpers on the component side). I have some ambitious fw and PC sw plans for it, so it's still in the lab, right now being used as an I2C console to debug another project I'm working on!

[Reply #37 on:]

Hey, good work on that LCD IO Backpack board! So you guys are making workshops around it?

We did a single workshop around it. Usually if we make something small, we build one of these boards and use them. The small proto-area for SMD components is cool too.

We had a bunch of the PCB's fabricated, and when they are all used up, we'll make some changes on it, and maybe selling them outside Labitat - who knows.

// Per.

[Reply #38 on:]

Good, that's good, go for it guys.
So that's an SMD prototyping area... good idea!

[Reply #39 on:]

@Njay

I check your site, Nice work by the way. You say you can not use an auto-reset feature when your program the Arduino using the RS-232.  Well you can !   It the DTR line... connect in serie a cap of 0.1 uF between DTR and the Reset of the Ardiuno. Program the ATMega328, and it will program just fine, and it will auto-reset.  I did program an Arduino chip ( ATMega328 with Ardiuno Bootloader ) using a Schmartboard RS-232 Module at http://www.schmartboard.com/index.asp?page=products_populated&id=84  The RS-232 adapter is base on the chip MAX232.


For a cheaper Ardiuno... Buy a breadboard ( small is fine, a big one is better ) , a pre-loaded ATMega328 with Arduino bootloader, a 16 MHz crystal, one 10 K resistor, one push-on switch, a few 0.1 uF, 2 - 22nF, somes wires  - The comunication module :  A FTDI - USB to TTL  module or RS-232 module  - RS232 to TTL <-- if your computer has a 9 pin serial out. For power, 3 battery of 1 1/2 V in series = 4.5 V ( AA, AAA, C, D <-- your pick )  will power the Arduino chip ( I did that and it work just fine ) .

Please note, when you program the chip, using a USB -TTL, disconnect the power going into the Arduino chip / circuit, the computer USB will provide the power.  When using the RS232 module, keep the power connected to your Arduino / chip.

My 2 cent

[Reply #40 on:]

22pF for the xtal, not 22nF
dipmicro has all the parts really inexpensive, except the bootloaded atmega

[Reply #41 on:]

They (dipmicro.com) also recently added RGB LEDs at reasonable prices plus they have TLC5490 to drive them

Here is my lcd back pack:

[Reply #42 on:]

Why 16 MHz? Why not 20 MHz for 20 MHz-capable chips? Does that make the rest iffy?

[Reply #43 on:]

Why 16 MHz? Why not 20 MHz for 20 MHz-capable chips? Does that make the rest iffy?

Maybe that wastes power if 20MHz is not needed and also that needs stable voltage of greater than 4.5V, which you can't get from 3 AA batteries. 16MHz can probably be safely run at that voltage. See fig. 28-1 on the atmega328 doc.

[Reply #44 on:]

Sorry CrossRoads for my typo. I mean 22pF, like you said.   

I did try to run my Ardiuno chip with 4.5 V using 3 AA batteries.... work fine - a temporary solution . But if I need to build into a permanent project, I will add a 7805 reg ( with input cap and output cap ) and a heatsink, that way, it will work fine.