walnux/Documentation/platforms/arm/rp2040/boards/adafruit-feather-rp2040/index.rst

=======================
Adafruit Feather RP2040
=======================

.. tags:: chip:rp2040

The Feather RP2040 is a general purpose RP2040 board supplied by 
Adafruit.

.. figure:: Feather.png
   :align: center

See the `Adafruit website <https://learn.adafruit.com/adafruit-feather-rp2040-pico/overview/>`_ for
information about Adafruit Feather RP2040.

Features
========

* RP2040 microcontroller chip
* Dual-core ARM Cortex M0+ processor, flexible clock running up to 133 MHz
* 264kB of SRAM, and 8MB of on-board Flash memory
* Castellated module allows soldering direct to carrier boards
* USB Host and Device support via type C connector.
* Low-power sleep and dormant modes
* Drag & drop programming using mass storage over USB
* 26 multi-function GPIO pins
* 2× SPI, 2× I2C, 2× UART, 3× 12-bit ADC, 16× controllable PWM channels
* Accurate clock and timer on-chip
* Temperature sensor
* Accelerated floating point libraries on-chip
* 8 × Programmable IO (PIO) state machines for custom peripheral support
* LiPoly Battery connector

Serial Console
==============

By default a serial console appears on pins 14 (RX GPIO0) and pin 15
(TX GPIO1).  This console runs a 115200-8N1.

The board can be configured to use the USB connection as the serial console.

Buttons and LEDs
================

User LED controlled by GPIO13.

A ws2812 (NeoPixel) smart RGB LED controlled by GPIO16.

An LED (CHG LED) that indicates the charging status of
connected LiPo cell.

There is a BOOT button which if held down when power is first
applied or the RESET button is pressed will cause the RP2040 to
boot into program mode and appear as a storage device to
a USB connector.  Saving a .UF2 file to this device will 
replace the Flash ROM contents on the RP2040.

A RESET button that allows rebooting the board without disconnecting
the power.

Pin Mapping
===========
Pads numbered anticlockwise from USB connector.

===== ========== ==========
Pad   Signal     Notes
===== ========== ==========
1     Reset      Pull to ground to reset the RP2040 processor.
2     3.3V       Power out to peripherals.
3     3.3V       Power out to peripherals.
4     Ground
5     GPIO26     ADC0
6     GPIO27     ADC1
7     GPIO28     ADC2
8     GPIO29     ADC3
9     GPIO24
10    GPIO25
11    GPIO18
12    GPIO19
13    GPIO20
14    GPIO1      Default RX for UART0 serial console
15    GPIO0      Default TX for UART0 serial console
16    GPIO6
17    GPIO2
18    GPIO3
19    GPIO7
20    GPIO8
21    GPIO9
22    GPIO10
23    GPIO11
24    GPIO12
25    GPIO13
26    VBUS       Connected to USB +5V
27    EN         Pull to ground to turn off 3.3V regulator.
28    VBAT       Connected to LiPo battery 3.3V.
===== ========== ==========

The board has a STEMMA QT connector that is also connected to
pins GPIO2 (I2C1 SDA) and GPIO3 (I2C1 SDA).

The board has a two pin JST PH socket that accepts a single 3.3V
LiPo cell.  The cell connected to this port can be charged by
connecting the board to a USB power supply.

There are solder pads on the board that allow the addition of
a 10-pin serial debug (SWD) connector.

Power Supply 
============

The Raspberry Pi Pico can be powered via the USB connector,
or by supplying +5V to pin 39.  The board had a diode that prevents
power from pin 39 from flowing back to the USB socket, although
the socket can be power via pin 30.

The Raspberry Pi Pico chip run on 3.3 volts.  This is supplied
by an onboard voltage regulator.  This regulator can be disabled
by pulling pin 37 to ground.

The regulator can run in two modes.  By default the regulator runs
in PFM mode which provides the best efficiency, but may be 
switched to PWM mode for improved ripple by outputting a one
on GPIO23. 

Supported Capabilities
======================

NuttX supports the following RP2040 capabilities:

* UART  (console port)

  * GPIO 0 (UART0 TX) and GPIO 1 (UART0 RX) are used for the console.

* I2C
* SPI (master only)
* DMAC
* PWM
* ADC
* Watchdog
* USB device

  * MSC, CDC/ACM serial and these composite device are supported.
  * CDC/ACM serial device can be used for the console.

* PIO (RP2040 Programmable I/O)
* Flash ROM Boot
* SRAM Boot

  * If Pico SDK is available, nuttx.uf2 file which can be used in BOOTSEL mode will be created.

* Persistent flash filesystem in unused flash ROM
* WiFi wireless communication

There is currently no direct user mode access to these RP2040 hardware features:

* SPI Slave Mode
* SSI
* RTC
* Timers

NuttX also provide support for these external devices:

* BMP180 sensor at I2C0 (don't forget to define I2C0 GPIOs at "I2C0 GPIO pin assign" in Board Selection menu)
* INA219 sensor / module (don't forget to define I2C0 GPIOs at "I2C0 GPIO pin assign" in Board Selection menu)
* SHT4X sensor at I2C0
* Pico Display Pack (ST7789 LCD)

  * RGB leds and buttons are not supported yet.

* Pico Audio Pack (PCM5100A I2S DAC)

  * I2S interface is realized by PIO.

* WS2812 smart pixel support

Installation
============

1. Download Raspberry Pi Pico SDK.

.. code-block:: console

  $ git clone -b 2.0.0 https://github.com/raspberrypi/pico-sdk.git

2. Download and install picotool

  Instructions can be found here: https://github.com/raspberrypi/picotool

  If you are on Arch Linux, you can install the picotool through the AUR:

.. code-block:: console

  $ yay -S picotool

3. Set PICO_SDK_PATH environment variable

.. code-block:: console

  $ export PICO_SDK_PATH=<absolute_path_to_pico-sdk_directory>

4. Configure and build NuttX

.. code-block:: console

  $ git clone https://github.com/apache/nuttx.git nuttx
  $ git clone https://github.com/apache/nuttx-apps.git apps
  $ cd nuttx
  $ make distclean
  $ ./tools/configure.sh raspberrypi-pico-w:nsh
  $ make V=1

5. Connect the Adafruit Feather RP2040 board to the USB port while pressing
   BOOTSEL.
   The board will be detected as USB Mass Storage Device.
   Then copy "nuttx.uf2" into the device.
   (Same manner as the standard Pico SDK applications installation.)

6. To access the console, GPIO 0 and 1 pins must be connected to the
   device such as USB-serial converter.

   `usbnsh` configuration provides the console access by USB CDC/ACM serial
   device.  The console is available by using a terminal software on the USB
   host.

Configurations
==============

audiopack
---------

NuttShell configuration (console enabled in UART0, at 115200 bps) with
support for NXPlayer audio player.

Pico Audio Pack support.
See the following page for connection:
https://shop.pimoroni.com/products/pico-audio-pack
SD card interface is also enabled.

composite
---------

NuttShell configuration (console enabled in UART0, at 115200 bps) with support for
CDC/ACM with MSC USB composite driver. ``conn`` command enables the composite
device.

displaypack
-----------

NuttShell configuration (console enabled in USB Port, at 115200 bps) supporting
ST7789 video display.

See the following page for connection:
https://shop.pimoroni.com/products/pico-display-pack

enc28j60
--------

NuttShell configuration (console enabled in UART0, at 115200 bps) with support for
ENC28J60.

ENC28J60 SPI ethernet controller supports:

  - IP address is configured by DHCP.
  - DNS address is 8.8.8.8 (CONFIG_NETINIT_DNSIPADDR)
  - NTP client is enabled.

.. list-table:: ENC28J60 connections
   :widths: auto
   :header-rows: 1

   * - ENC28J60
     - Raspberry Pi Pico W
   * - GND
     - GND (Pin 3 or 38 or ...)
   * - 3.3V
     - 3V3 OUT (Pin 36)
   * - SI
     - GP15 (SPI1 TX) (Pin 20)
   * - SCK
     - GP14 (SPI1 SCK) (Pin 19)
   * - CS
     - GP13 (SPI1 CSn) (Pin 17)
   * - SO
     - GP12 (SPI1 RX) (Pin 16)
   * - INT
     - GP11 (Pin 15)
   * - RESET
     - GP10 (Pin 14)

lcd1602
-------

NuttShell configuration (console enabled in UART0, at 115200 bps) with support for
LCD1602 Segment LCD Display (I2C).

.. list-table:: LCD1602 connections
   :widths: auto
   :header-rows: 1

   * - PCF8574 BackPack 
     - Raspberry Pi Pico W
   * - GND
     - GND (Pin 3 or 38 or ...)
   * - VCC
     - 5V Vbus (Pin 40)
   * - SDA
     - GP4 (I2C0 SDA) (Pin 6)
   * - SCL
     - GP5 (I2C0 SCL) (Pin 7)

nsh
---

Basic NuttShell configuration (console enabled in UART0, at 115200 bps).

nsh-flash
---------

Basic NuttShell configuration (console enabled in UART0, at 115200 bps
with SMART flash filesystem.

nshsram
-------

NuttShell configuration (console enabled in UART0, at 115200 bps) with interrupt
vectors in RAM.

smp
---

Basic NuttShell configuration (console enabled in UART0, at 115200 bps) with
both ARM cores enabled.

spisd
-----

NuttShell configuration (console enabled in UART0, at 115200 bps) with SPI SD
card support enabled.

.. list-table:: spisd connections
   :widths: auto
   :header-rows: 1

   * - SD card slot
     - Raspberry Pi Pico W
   * - DAT2          
     - Not connected
   * - DAT3/CS
     - GP17 (SPI0 CSn) (Pin 22)
   * - CMD /DI
     - GP19 (SPI0 TX)  (Pin 25)
   * - VDD
     - 3V3 OUT (Pin 36)
   * - CLK/SCK
     - GP18 (SPI0 SCK) (Pin 24)
   * - VSS
     - GND (Pin 3 or 38 or ...)
   * - DAT0/DO
     - GP16 (SPI0 RX)  (Pin 21)
   * - DAT1          
     - Not connected

Card hot swapping is not supported.

ssd1306
-------

NuttShell configuration (console enabled in UART0, at 115200 bps) with support
for SSD1306 OLED display (I2C) test configuration.

.. list-table:: SSD1306 connections
   :widths: auto
   :header-rows: 1

   * - SSD1306
     - Raspberry Pi Pico W
   * - GND
     - GND (Pin 3 or 38 or ...)
   * - VCC
     - 3V3 OUT (Pin 36)
   * - SDA
     - GP4 (I2C0 SDA) (Pin 6)
   * - SCL   
     - GP5 (I2C0 SCL) (Pin 7)

st7735
------

NuttShell configuration (console enabled in UART0, at 115200 bps) with support for
ST7735 SPI LCD.

.. list-table:: ST7735 connections
   :widths: auto
   :header-rows: 1

   * - st7735
     - Raspberry Pi Pico W
   * - GND
     - GND (Pin 3 or 38 or ...)
   * - VCC
     - 5V Vbus (Pin 40)
   * - SDA
     - GP15 (SPI1 TX) (Pin 20)
   * - SCK
     - GP14 (SPI1 SCK) (Pin 19)
   * - CS
     - GP13 (SPI1 CSn) (Pin 17)
   * - AO(D/C)
     - GP12 (SPI1 RX) (Pin 16)
   * - BL
     - GP11 (Pin 15)
   * - RESET
     - GP10 (Pin 14)


usbmsc
------

NuttShell configuration (console enabled in UART0, at 115200 bps) with support for
USB MSC and CDC/ACM.

``msconn`` and ``sercon`` commands enable the MSC and CDC/ACM devices. The MSC
support provides the interface to the SD card with SPI, so the SD card slot
connection like spisd configuration is required.

usbnsh
------

Basic NuttShell configuration using CDC/ACM serial (console enabled in USB Port,
at 115200 bps).

waveshare-lcd-1.14
------------------

NuttShell configuration (console enabled in UART0, at 115200 bps) with support for
st7789.

waveshare-lcd-1.3
-----------------

NuttShell configuration (console enabled in UART0, at 115200 bps) with support for
usbmsc.

License exceptions
==================

The following files are originated from the files in Pico SDK.
So, the files are licensed under 3-Clause BSD same as Pico SDK.

* arch/arm/src/rp2040/rp2040_clock.c
* arch/arm/src/rp2040/rp2040_pll.c
* arch/arm/src/rp2040/rp2040_xosc.c

  * These are created by referring the Pico SDK clock initialization.

* arch/arm/src/rp2040/rp2040_pio.c
* arch/arm/src/rp2040/rp2040_pio.h
* arch/arm/src/rp2040/rp2040_pio_instructions.h

  * These provide the similar APIs to Pico SDK's hardware_pio APIs.

* arch/arm/src/rp2040/hardware/\*.h

  * These are generated from rp2040.svd originally provided in Pico SDK.