%%alias Aliased from [ItsyBitsy] and [M4 Express|M4Express] %%

The __ItsyBitsy M4 Express __ uses the __Microchip ATSAMD51 Cortext M4__ processor running at 120 MHz, with floating point support and __512KB Flash and 192KB RAM__. It's quite tiny, at 35mm long by 18mm wide, and has 6 power pins, 23 digital [GPIO] pins (7 of which can be analog in, 2 x 1 MSPS analog out DACs, and 18 x PWM out). It has 2MB of SPI Flash memory to contain your program code. It receives both its power and connection to the outside world via a micro USB connection.
 

!! Programming 

The ItsyBitsy can be programmed in [CircuitPython], and from AdaFruit comes preinstalled with a CircuitPython UF2 bootloader. You can install an alternative bootloader if you want to program it in some other language, but we're happy with CircuitPython. 

The steps are:

* create your Python code in a file named "code.py" or "main.py"
* attach the ItsyBitsy to your computer using a USB cable. It should show up as a drive named "CIRCUITPY" on your desktop. The LED on the M4 Express will glow green.
* drag-and-drop your python file onto the mounted drive
* push the tiny reset button once. The ItsyBitsy will load and execute the code.py file

If you want to update your code just drag a new version onto the drive. You should see the results immediately as the M4 Express senses a change in the file.

!! Example Python Code

This file, named "code.py" causes the little red LED on the ItsyBitsy to blink:
{{{
import board
import digitalio
import time

led = digitalio.DigitalInOut(board.D13)
led.direction = digitalio.Direction.OUTPUT

while True:
    led.value = True
    time.sleep(0.8) # how much time on?
    led.value = False
    time.sleep(1.8) # how much time off?
}}}

!! Links

* [Overview|https://learn.adafruit.com/introducing-adafruit-itsybitsy-m4] on AdaFruit
* [Download Mu|https://codewith.mu/en/download] 
* [Installing the Mu Editor|https://learn.adafruit.com/adafruit-metro-m0-express-designed-for-circuitpython/installing-mu-editor] on AdaFruit
* [UF2 Bootloader|https://github.com/Microsoft/uf2] on github