Pinout and mold are Xiao-compatible, with castellated pads, so you can solder it to a PCB with a cutout to allow some breathing space for the lower components. In addition to the QT port, we also have an RGB NeoPixel (with a controllable power pin to allow very low power usage usage) and both boot mode and reset buttons (ideal for restarting your program or entering the bootloader). This QT Py comes with loose 1/8" pin headers that you can solder in for use with breadboards. While the RP2040 has a lot of onboard RAM (264KB), it does not have built-in flash memory. Instead, this is provided by the external QSPI flash chip. On this board there are 8MB used between the running program and any MicroPython or CircuitPython file storage. When using C/C++, you get all the flash memory, when using Python you will be left about 7MB for code, files, images, fonts, etc. Same size, form factor and pin out as our SAMD-based QT Py USB Type C connector - If you only have Micro B cables, this adapter comes in handy. RP2040 32-bit Cortex M0+ Dual-Core runs at ~125MHz @ 3.3V Logic and Performance 264KB RAM 8MB SPI FLASH chip for storing files and CircuitPython/MicroPython code storage. No EEPROM native USB supported by any operating system - can be used as a USB serial console, MIDI, keyboard Mouse HID, even a small drive can be used to store Python scripts. 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 PWM outputs s on any IO pin - for servos, LEDs, etc. There are 6 GPIO in consecutive order for PIO compatibility, 3.3V regulator with 600mA peak output, 12MHz crystal. Both reset button and bootloader selection buttons for quick restarts (no unplugging and re-plugging the relaunch code). Really small.