ItsyBitsy

ItsyBitsy

Manufacturer	Adafruit
Host port	USB Micro B
Microcontroller	Various
Digital I/O pins	21, 22 or 23 (depending on board)
I/O Voltage	3.3V or 5V (depending on board)
Website	www.adafruit.com/category/1008

The ItsyBitsy is a range of microcontroller boards in DIL form factor developed by Adafruit, intended for Arduino or CircuitPython.

Description

Pins are labelled with Arduino/CircuitPython numbering.

The pinout is not exactly the same on all boards. The ItsyBitsy 32u4 5V variant is the only variant that is fully 5V-capable and with a full 23 GPIO pins. On the other boards, which run on 3.3V, pin #5 is connected through a level-shifter, being a 5V-logic level output pin only. The 3.3V boards also have VHigh pin which outputs the higher of VBAT and VBUS. Most boards have 2 or 3 pins also on the short edge.

All boards come with a Reset button and a red LED connected to pin #13 (active high). The ARM Cortex M-based models have also a RGB LED of some kind, which the ATmega32u4 models lack.

All boards have a USB Micro-B port but with a through-hole soldered shield — which should make it more durable than a standard USB Micro-B port.

Boards

ItsyBitsy 32u4

Has a AVR ATmega32u4 8-bit microcontroller which has an integrated USB controller.

The ItsyBitsy 32u4 is sold in a 3.3 V variant (8 MHz) and a 5 V variant (16 MHz). There is no RGB LED.

Both variants have power regulators (to 3.3V or 5V) for running on external battery, and the 5V variant also outputs an additional 3.3V.

Note that on the 5V variant, some pins have different polarity and the #5 pin is both input and output. On the 3.3V variant, the VHigh pin outputs the highest of VBAT and VUSB.

They use an Adafruit variant of the Caterina bootloader.

ItsyBitsy RP2040

Has the RP2040 microcontroller like the Raspberry Pi Pico, and 8 MB of Flash. It has 22 GPIO pins plus pin #5 (the Pico has 26). Has a NeoPixel RGB LED. The buttons are Reset and Boot like on the Pico.

All RP2040-based boards have the same bootloader in ROM from the factory.

The RP2040 GPIO port numbers (not Arduino numbers) are printed on the bottom of the board. However, the silkscreen is incorrect in the first batch (and in some product images) for pin #5: It is connected to GPIO14, not GPIO16 (which powers the NeoPixel

ItsyBitsy nRF52840 Express

Has the Nordic Semiconductor nRF52840 which supports USB and Bluetooth (among other wireless protocols). The MCU is an ARM Cortex M4 at 64 MHz. It has 1 MB of Flash. There is an additional 2 MB QSPI Flash, intended for CircuitPython programs. Has a mini DotStar RGB LED. Has a SW button beside the Reset button.

ItsyBitsy M0 Express

Has a ATSAMD21 microcontroller, with a ARM Cortex M0+ MCU at 48 MHz, 256 KB Flash and 32 KB RAM. There is an additional 2 MB SPI Flash, intended for CircuitPython programs. Has a DotStar RGB LED.

ItsyBitsy M4 Express

Has a ATSAMD51 microcontroller, with an ARM Cortex M4 MCU at 120 MHz, 512 KB Flash and 192 KB RAM. There is an additional 2 MB SPI Flash, intended for CircuitPython programs. Has a DotStar RGB LED.

Pinout

Sides

Name	RP2040	32u4	↑					32u4	RP2040	Name
RST								VBAT
VCC								GND
AREF, VCC or EN								VBUS
								PC7	GP11	13
A0	GP26	PF7						PD6	GP10	12
A1	GP27	PF6						PB7	GP09	11
A2	GP28	PF5						PB6	GP08	10
A3	GP29	PF4						PB5	GP07	9
A4	GP24	PF1						PE6	GP06	7
A5	GP25	PF0						PC6	GP14	5!
SCK	GP18	PB1						PD0	GP03	SCL
MOSI	GP19	PB2						PD1	GP02	SDA
MISO	GP20	PB3						PD3	GP00	1/TX
	GP12							PD2	GP01	0/RX

Short edge

32u4 5V	3V	En	GND	PB4/8	PD7/6	PD4/4	PD2/RX/0
32u4 3V	GND	En	GND	PB4/8	PD7/6	PD4/4	PD2/RX/0
RP2040	GP12/2	En	SWDIO	SWCLK	GP05/3	GP03/4	GP01/RX
M0/M4 Express	2	En	swdio	swclk	3	4	RX/0
nRF52840	D2	no short edge					RX/0

Internal

Board	RGB LED Power	RGB LED Data	Button	Unconnected
32u4				PB0, PD5
RP2040	GPIO 11	GPIO 16	GPIO 17	GPIO 15, 21, 22 and 23