No need to call `require "cyw43"` on Pico W

To ensure consistency with the article in n-monthly Lambda Node Vol.4 No.1

Full Changelog: 0.2.0...0.2.1

require, PWM, Watchdog and BLE (experimental)

What's Changed

• You can load external libraries by require method.
  See also PRK Firmware's wiki https://github.com/picoruby/prk_firmware/wiki/require
• PWM (Pulse Width Modulation) class.
  See API guideline https://github.com/mruby/microcontroller-peripheral-interface-guide/blob/main/mruby_io_PWM_en.md
• Watchdog class.
  Example https://github.com/picoruby/picoruby/tree/master/mrbgems/picoruby-watchdog/example
• [Experimental] BLE class for Raspberry Pi Pico W. Use "R2P2_W-*.uf2" binary.
  Examples (possibly buggy) https://github.com/picoruby/picoruby/tree/master/mrbgems/picoruby-ble/example
• Fixed a lot of bugs.

Full Changelog: 0.1.2...0.2.0

UART added and other peripheral libraries fixed

• GPIO
• ADC
• I2C
• SPI
• UART

These gems are implemented according to API guidelines: https://github.com/mruby/microcontroller-peripheral-interface-guide

Shell improved

• You can copy & paste into the R2P2 shell (line by line. Multiple lines will fail)
• You can interrupt a task by Ctrl-C
• Shell can start even if the terminal size is small

General peripheral classes: GPIO, ADC, I2C, and SPI

GPIO

The image below shows how to turn on and off the LED on Raspberry Pi Pico:

Note that you (generally) have to answer n to some questions being asked on start-up.

ADC

You can calculate the current temperature by RP2040's on-chip sensor:

I2C and SPI

[TODO]

Flash disk works

Improvements

• Filesystem now works on the Flash ROM in RP2040 so your data will persist even after power down

Known issues

• irb -> exit -> irb then, the shell falls into an infinity loop due to a multi-tasking problem

The first release🎉

There are still many bugs, but released anyway!