QT Py

Two Versions of the QT Py

• AdaFruit has SAMD21 and RP2040 versions of the QT Py
  • Same pinouts/form factors
• RP2040 vs SAM version
  • RP2040 is faster (125 MHz vs 48 MHz)
  • RP2040 has 2 cores vs 1
  • RP2040 has more Flash
  • RP2040 has more SRAM
  • The RP2040 version is more expensive, but about the same cost if the SAM version is used with an external Flash

SAMD21 QT Py

• Adafruit QT Py SAMD21 Product Page
  • ATSAMD21E18 32-bit Cortex M0+ version
  • 48 MHz, 32-bit processor
  • 256KB Flash
  • 32 KB RAM
• Native USB supported by every OS
  • Can be used in Arduino or CircuitPython as USB serial console, MIDI, Keyboard/Mouse HID, even a little disk drive for storing Python scripts.
• Built in RGB NeoPixel LED
• 11 GPIO pins:
  • True analog output on one I/O pin
    • Can be used to play 10-bit quality audio clips in Arduino
      • CircuitPython does not have storage for audio clips
  • 9 x 12-bit analog inputs (SDA/SCL do not have analog inputs)
  • 1 x Optional AREF on A1
  • 9 x PWM outputs (A0 is analog out, A1 is not PWM capable)
  • Hardware I2C port with STEMMA QT plug-n-play connector
  • Hardware UART
  • Hardware SPI
  • Hardware I2S
  • 6 x Capacitive Touch with no additional components required
• 3.3V regulator with 600mA peak output AP2112
• Optional SOIC-8 SPI Flash chip on bottom
  • Can't use castellated pins if Flash on bottom is installed
  • GD25Q16
  • Access the SPI flash in Arduino on SPI1 and chip select pin 17
  • In CircuitPython, a 'haxpress' version of the runtime will need to be installed, so it knows to look for the larger filesystem
  • There is more hardware support in the haxpress CircuitPython build because we can add more code to the internal flash instead of using it for a filesystem
• Reset switch for starting your project code over or entering bootloader mode
• USB Type C connector

RP2040 QT Py

• Adafruit QT Py RP2040 Product page
• USB Type C connector
• RP2040 32-bit Cortex M0+ dual-core
• Runs at ~125 MHz
• 264 KB RAM
• 8 MB SPI FLASH chip for storing files and CircuitPython/MicroPython code storage. No EEPROM
• Can be used with MicroPython or CircuitPython
• Built-in RGB NeoPixel LED
• 13 GPIO pins (11 breakout pads and two QT pads):
  • Four 12 bit ADCs (one more than Pico)
  • Two I2C ports (one on the QT connector, one on the breakout pads)
  • SPI and UART peripherals, in standard QT Py locations,
  • PWM outputs on every IO pin - for servos, LEDs, etc
  • There are 6 GPIO in consecutive order for PIO compatibility
• 3.3V logic and power 600 mA
• Both Reset button and Bootloader select buttons for quick restarts (no unplugging-replugging to relaunch code)

Links

• Adafruit QT Py page
• Adafruit Learning System for QT Py

Pins

3V

• Regulated output from the onboard regulator. You can draw 500mA

5V

• 5v out from the USB port.
• You can also use this as a voltage input but you must have some sort of diode (schottky, signal, power, really anything) between your external power source and this pin with anode to battery, cathode to 5V pin.
• Note that you cannot power the USB port by supplying 5V to this pin: there is a protection diode that prevents the 5V from reaching the USB connector.
• This is to protect host computer USB ports, etc.

A0 / D0 - Digital/analog GPIO pin 0

• Can act as a true analog output with 10 bit precision, but does not have PWM. Can also be a capacitive touch input.

A1 / D1 - Digital/analog GPIO pin 1

• Can be a capacitive touch input or an AREF pin.

A2 / D2 - Digital/analog GPIO pin 2

• Can act as PWM or capacitive touch input.

A3 / D3 - Digital/analog GPIO pin 3

• Can act as PWM or capacitive touch input.

SDA / D4

• This is the I2C data pin and digital pin 4, can also be a PWM
• There is no analog on this pin!
• There's no pull up on this pin by default so when using with I2C, you may need a 2.2K-10K pullup on each to 3.3V.
• All our STEMMA QT breakouts have the pullup installed on the breakout PCB.

SCL / D5

• This is the I2C clock pin and digital pin 5, can also be a PWM
• There is no analog on this pin! There's no pull up on this pin by default so when using with I2C, you may need a 2.2K-10K pullup on each to 3.3V

TX / A6 / D6

• Transmit (output) for Serial1
• Also analog/digital GPIO 6.
• Can act as PWM or capacitive touch input.

RX / A7 / D7

• Receive (input) for Serial1
• Also analog/digital GPIO 7.
• Can act as PWM or capacitive touch input.*

SCK / A8 / D8

• Hardware SPI clock pin
• Also analog/digital GPIO 8. Can act as PWM output.

MISO / A9 / D9

• Also analog/digit* Hardware SPI MISO microcontroller in serial out pin

al GPIO 9. Can act as PWM output.

MOSI / A10 / D10

• Hardware SPI MOSI microcontroller out serial in pin
• Also analog/digital GPIO 10. Can act as PWM output.

NeoPixel

• Connected to digital pin 11 for signal
• If you would like to turn off the pixel for low power usage, set pin 12 low.
• By default pin 12 is set high for you by Arduino/CircuitPython

Programming

• C/C++ or CircuitPython

C/C++

• RP2040 C/C++ SDK

MicroPython

• RP2040 MicroPython Repo

CircuitPython

• Adafruit CircuitPython 6.1.0 on 2021-01-21; Adafruit QT Py M0 Haxpress with samd21e18
• CircuitPython is a derivative of MicroPython.
  • QT Py Haxpress used with 2MB Flash EEPROM
• blink.py for QT Py
• Mu editor
• CircuitPython looks for a code file on the board to run
  • There are four options: code.txt, code.py, main.txt and main.py
  • CircuitPython looks for those files, in that order, and then runs the first one it finds
• How do I check how much memory I have free?

import gc
gc.mem_free()

• Reports about 19KB of free space

Will give you the number of bytes available for use.

Land Boards Python Code

• GitHub

Digital I/O Example

import board
import digitalio
import time

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

while True:
    led.value = True
    time.sleep(0.1)
    led.value = False
    time.sleep(0.5)

Flash EEPROM 2 MB