Arduino Size

What's the smallest MCU (Arduino) that I can use on a custom PCB?

Looking for something like the Arduino Pro Mini.

My goal is to integrate the MCU into a small PCB and interface using the Arduino IDE.

Thoughts?

Look at the available packages to find the smallest. As far as I know, the TQFP is the smallest they make.

An ATmega328P-MMH is approx. 4 x 4 x 1 mm according to the datasheet. If you don't need so many pins, you could consider using an attiny instead.

The small leadless parts are pretty darn small!
Search the forum for "femtoduino" for an example of a really small card.

http://forum.arduino.cc/index.php?topic=24449.0

For the 328p specifically, the 28 MLF (VQFN) package is the smallest at 4mm x 4mm. The 32 M1 version is 4.9mm x 4.9 mm, followed by the TQFP at 9mm x 9mm. Generally, MLF packages tend to be smaller because there are no pins, they have pads along the edges. BGAs can be smaller. For example, take the 32_4_pa, it comes in PDIP, TQFP, MLF, DRQFP, and a VFBGA package.

PDIP: 52mm x 15mm
44 TQFP: 12mm x 12mm
44 MLF: 7mm x 7 mm
DRQFN: 5mm x 5mm
VFBGA: 5mm x 5mm

Thanks for all the great tips and links guys.

I'm a noob to the platform so my goals are to connect a small MCU to a board like the Seeduino Film (Seeed Studio Bazaar, The IoT Hardware enabler.)

Looks like there's an Atmega168 on-board that PCB. My goals are to connect 2-3 sensors on this PCB and get the data via Bluetooth (in the simplest terms possible).

Forgive the noob questions: is the Atmega168 a capable enough MCU that can be used with the Arduino IDE to process the sensor data? Do I even need an Arduino with this board?

Thanks in advance

dakrisht:
(Seeed Studio Bazaar, The IoT Hardware enabler.)

Do I even need an Arduino with this board?

From the looks of it, that board already has an AVR processor on it, so there is no need to "add an Arduino"

Make sense, thanks for that. How do you interface with this board - no USB or connector on it?

dakrisht:
Make sense, thanks for that. How do you interface with this board - no USB or connector on it?

If by "interface" you mean connect to the computer via USB for programming and communications, you need a USB to serial converter. If you look at the Wiki page that is linked on the product page, there of such a device.

Thanks, was asking exactly that. I guess it would be their Bluetooh or USB connector. Wonder of other Bluetooth modules would fit this thing...

Any links for a UartSB that would be flush or flat with the PCB? The ones I have found are either to tall and stick out tremendously and $30+

Do you really need it to be flush or flat if you are just using it when you program it?

Any USB/Serial module with USB Mini-B and 0.1" headers will be about the same size. If it is based on FT232R, then it will be crystal-less and about as small as it gets.

Arrch:
Do you really need it to be flush or flat if you are just using it when you program it?

Using it to transmit data from the circuit. What about TI BT chips? Like the CC2541? Or are we talking custom circuits at this point?

Looks like the Bluetooth Frame might be the way to go here: http://www.seeedstudio.com/wiki/Bluetooth_Frame