Merge pull request #867 from sctv/patch-3

Update adafruit_feather_rp2040.md

Author: makermelissa

_board/adafruit_feather_rp2040.md

@@ -51,7 +51,7 @@ For peripherals, there are two I2C controllers, two SPI controllers, and two UAR
 
 You'll note there's no I2S peripheral, or SDIO, or camera, what's up with that? Well instead of having specific hardware support for serial-data-like peripherals like these, the RP2040 comes with the PIO state machine system which is a unique and powerful way to create custom hardware logic and data processing blocks that run on their own without taking up a CPU. For example, NeoPixels - often we bitbang the timing-specific protocol for these LEDs. For the RP2040, we instead use PIO object that reads in the data buffer and clocks out the right bitstream with perfect accuracy. Same with I2S audio in or out, LED matrix displays, 8-bit or SPI based TFTs, even VGA! In MicroPython and CircuitPython you can create PIO control commands to script the peripheral and load it in at runtime. There are 2 PIO peripherals with 4 state machines each.
 
- There is great [C/C++ support](https://github.com/raspberrypi/pico-sdk), an official [MicroPython port](https://github.com/raspberrypi/micropython), and a [CircuitPython port](/downloads)!** We of course [recommend CircuitPython because we think it's the easiest way to get started](https://learn.adafruit.com/welcome-to-circuitpython) and it has support with most of our drivers, displays, sensors, and more, supported out of the box so you can follow along with our CircuitPython projects and tutorials. **At the time of launch, there is was no Arduino core support for this board. Earl Philhower has developed an Arduino supported [core](https://github.com/earlephilhower/arduino-pico).
+There is great [C/C++ support](https://github.com/raspberrypi/pico-sdk), unofficial (but really good) [Arduino support](https://github.com/earlephilhower/arduino-pico), an official [MicroPython port](https://github.com/raspberrypi/micropython), and a [CircuitPython port](/downloads). We of course [recommend CircuitPython because we think it's the easiest way to get started](https://learn.adafruit.com/welcome-to-circuitpython) and it has support with most of our drivers, displays, sensors, and more, supported out of the box so you can follow along with our CircuitPython projects and tutorials.
 
 While the RP2040 has lots of onboard RAM (264KB), it does not have built-in FLASH memory. Instead, that is provided by the external QSPI flash chip. **On this board there is 8 MB**, which is shared between the program it's running and any file storage used by MicroPython or CircuitPython. When using C/C++ you get the whole flash memory, if using Python you will have about 7 MB remaining for code, files, images, fonts, etc.