Add basic documentation

Author: earlephilhower

README.md

@@ -4,7 +4,7 @@
 
 Raspberry Pi Pico Arduino core, for all RP2040 and RP2350 boards
 
-This is a port of Arduino to the RP2040 (Raspberry Pi Pico processor) and RP2350 (Raspberry Pi Pico 2 processor). It uses the bare Raspberry Pi Pico SDK and a custom GCC 12.3/Newlib 4.0 toolchain.
+This is a port of Arduino to the RP2040 (Raspberry Pi Pico processor) and RP2350 (Raspberry Pi Pico 2 processor). It uses the bare Raspberry Pi Pico SDK and a custom GCC 14.2/Newlib 4.3 toolchain and supports ARM and RISC-V cores.
 
 # Documentation
 See https://arduino-pico.readthedocs.io/en/latest/ along with the examples for more detailed usage information.
@@ -126,6 +126,7 @@ Read the [Contributing Guide](https://github.com/earlephilhower/arduino-pico/blo
 * Peripherals:  SPI master/slave, Wire(I2C) master/slave, dual UART, emulated EEPROM, I2S audio input/output, Servo
 * printf (i.e. debug) output over USB serial
 * Transparent use of PSRAM globals and heap (RP2350 only)
+* ARM or RISC-V (Hazard3) support for The RP2350
 
 The RP2040 PIO state machines (SMs) are used to generate jitter-free:
 * Servos

docs/index.rst

@@ -7,7 +7,7 @@ RP2040 (Raspberry Pi Pico processor) and RP2350 (Raspberry Pi Pico 2
 processor), intended to make it easier and more fun to use and
 program the Raspberry Pi Pico / RP2040 / RP2350 based boards.
 
-This Arduino core uses a custom toolset with GCC 12.3 and Newlib 4.0.0
+This Arduino core uses a custom toolset with GCC 14.2 and Newlib 4.3
 and doesn't require any system-installed prerequisites.
 
 For the latest version, always check https://github.com/earlephilhower/arduino-pico

docs/platformio.rst

@@ -309,6 +309,19 @@ local copy of the core (with e.g. some modifications) on disk (`see documentatio
 Note that this can only be done for versions that have the PlatformIO
 builder script it in, so versions before 1.9.2 are not supported.
 
+Selecting the CPU architecture
+------------------------------
+
+By default Platform.IO will build for the onboard ARM cores on the RP2350.  To build RISC-V binaries
+adjust the ``board_build.mcu`` option accordingly:
+
+.. code:: ini
+
+    ; RP2350 based (RISC-V)
+    [env:rpipico2-riscv]
+    board = rpipico2
+    board_build.mcu = rp2350-riscv
+
 Examples
 --------
 

docs/rp2350.rst

@@ -6,7 +6,14 @@ is supported by the core with some minor caveats:
 
 * PSRAM is supported via a new ``pmalloc`` call and ``PSRAM`` variable decorator.
 * Both RP2350A and RP2350B (48 GPIOs) are supported.
-* Only ARM mode is available.  For RISC-V (Hazard3), please use the raw SDK.
+
+ARM and RISC-V Modes
+~~~~~~~~~~~~~~~~~~~~
+
+Either set of cores can be used on the RP2350, ARM Cortex-M33 or RISC-V Hazard3.
+Select the desired core from the IDE menus under ``Tools->CPU Architecture``.
+As of the initial release, all libraries should work under the new RISC-V mode with
+the exception of FreeRTOS.  If not, patches are always welcome.
 
 P2350-E9 Errata ("Increased leakage current on Bank 0 GPIO when pad input is enabled")
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~