August 29, 2010

3.3V Regulated Voltage Supply

Planning to realize an SD Card interface for Arduino, since it requires 3.3V supply, I've realized a simple one based on a general purpouse LM317 Voltage Regulator.

This is the schematic I've used:



In LM317 theory, using 330R (R1) and 545 (R2) one should get 3.31V. Actually, 330R is common, and I've got 545R by adding 470R and 75R in series.

This is the circuit on a stripboard:



And this is an example of realization:


Giving 5V input, the measured output is 3.33V.

August 23, 2010

YAMA - Yet Another Minimal Arduino

Yes, yet another minimal Arduino, using a simple stripboard. It comes with a 5V regulator on-board. Here is the schematics ad parts list:


It is also easy to build a minimal shield, to build projects on top. Here is how:


Here is a minimal-Arduino implementation:



Here is a shield implementation (it uses self-made extra-long stackable headers, something like these ones, that can be easily soldered under the stripboard):



And here is the minimal Arduino with its shield on top:



...ready to host some project...

[UPDATE]
Please, note that this implementation takes the schematics from this official standalone version, but it has a strange wiring of AREF pin to VCC(+5V). This should be avoided (accordingly to ATMEGA328 datasheet) and, in fact, official Arduino schematics does not have such a connection, and adds a 100nF cap between AREF and GND for noise reduction when using analog input pins. You can refer to this new post for a more correct version.

August 15, 2010

Simple LCD board

This is a simple LCD board to move an LCD based on HD44780 interface from prototyping to a more stable still not permanent setup.

It is based on this stripboard I recently got, which simplifies a bit the connections:


Here is the realization schema on this stripboard:


And here is the board:


A couple of spare female headers are used as minimal LCD support. Here is the LCD plugged in:


Eight pins are required to wire it up to Arduino (or minimal one), six towards digital pins and two for power.

August 9, 2010

Minimal Arduino on a Droids 1000Pads

This is a minimal Arduino built with minimal components using the excellent Droids 1000Pads Mini Basic Breadboard from DROIDS.

Here is the layout:


Here is a possible generic exposure of ATMEGA pins:


Here is a realization. Please, note that flipping the 1000Pads Mini Breadboard you have to reverse the power strips (+ and -) with respect to the previous layout schema.


And here is the Minimal Arduino running the blink example (the ATMEGA chip is on two stacked IC sockets).


Power is coming from a simple 5V regulator based on 7805.

[UPDATE]
Please, note that this implementation takes the schematics from this official standalone version, but it has a strange wiring of AREF pin to VCC(+5V). This should be avoided (accordingly to ATMEGA328 datasheet) and, in fact, official Arduino schematics does not have such a connection, and adds a 100nF cap between AREF and GND for noise reduction when using analog input pins. You can refer to this new post for a more correct version.

August 8, 2010

Simple 5V regulator

This is a simple 5V regulator to be used to power a minimal Arduino...

Here is the circuit schematics:


Here is the realization on a breadboard:



Here is the realization schema on a stripboard:


And here it is:


Two pins to be easily plugged in...

August 1, 2010

Stack IC Sockets instead of using a ZIF socket on the Arduino board

I needed an easy way to swap ATMEGA chips on the Arduino board, to be able to program them the usual way through the Arduino IDE and to transfer them on the final PCB.

Someone has used somehow a ZIF socket, someone else has built custom ZIF PCB. Here's a simple idea: use another IC socket between the PCB socket and the chip to cancel the stress on the chip when removing it.


Take an Arduino board (this one is running the Blink example):


Gently pull apart the ATMEGA chip (e.g. using one small screwdriver and toothpick): GENTLY (alternating from one side to the other one)...


Here's the chip extracted:


Take another IC socket (28 pins):


and insert it on the IC socket on the PCB:


This way, the stress removing the socket is not trasferred to the chip on the top:


Then add again the ATMEGA chip:


Here's the board running the Blink example again:


Then take another ATMEGA chip (this one has the bootloader alredy loaded in):


With the help of a breadboard, insert the chip on another IC socket:


Here's a new ATMEL brick waiting for programming:


Since the chip on the board is now a bit higher, you probably need extra long header strips on the shields. I've made my own ones.

BTW, if you really like ZIF sockets, you can still stack a ZIF socket (narrow, 28 pins, like this one) on the IC socket on the PCB...