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# The RP2 port
This is a port of MicroPython to the Raspberry Pi RP2 series of microcontrollers.
Currently supported features are:
- REPL over USB VCP, and optionally over UART (on GP0/GP1).
- Filesystem on the internal flash, using littlefs2.
- Support for native code generation and inline assembler.
- `utime` module with sleep, time and ticks functions.
- `uos` module with VFS support.
- `machine` module with the following classes: `Pin`, `ADC`, `PWM`, `I2C`, `SPI`,
`SoftI2C`, `SoftSPI`, `Timer`, `UART`, `WDT`.
- `rp2` module with programmable IO (PIO) support.
See the `examples/rp2/` directory for some example code.
## Building
The MicroPython cross-compiler must be built first, which will be used to
pre-compile (freeze) built-in Python code. This cross-compiler is built and
run on the host machine using:
$ make -C mpy-cross
This command should be executed from the root directory of this repository.
All other commands below should be executed from the ports/rp2/ directory.
Building of the RP2 firmware is done entirely using CMake, although a simple
Makefile is also provided as a convenience. To build the firmware run (from
this directory):
$ make clean
$ make
You can also build the standard CMake way. The final firmware is found in
the top-level of the CMake build directory (`build` by default) and is
called `firmware.uf2`.
## Deploying firmware to the device
Firmware can be deployed to the device by putting it into bootloader mode
(hold down BOOTSEL while powering on or resetting) and then copying
`firmware.uf2` to the USB mass storage device that appears.
If MicroPython is already installed then the bootloader can be entered by
executing `import machine; machine.bootloader()` at the REPL.
## Sample code
The following samples can be easily run on the board by entering paste mode
with Ctrl-E at the REPL, then cut-and-pasting the sample code to the REPL, then
executing the code with Ctrl-D.
### Blinky
This blinks the on-board LED on the Pico board at 1.25Hz, using a Timer object
with a callback.
```python
from machine import Pin, Timer
led = Pin(25, Pin.OUT)
tim = Timer()
def tick(timer):
global led
led.toggle()
tim.init(freq=2.5, mode=Timer.PERIODIC, callback=tick)
```
### PIO blinky
This blinks the on-board LED on the Pico board at 1Hz, using a PIO peripheral and
PIO assembler to directly toggle the LED at the required rate.
```python
from machine import Pin
import rp2
@rp2.asm_pio(set_init=rp2.PIO.OUT_LOW)
def blink_1hz():
# Turn on the LED and delay, taking 1000 cycles.
set(pins, 1)
set(x, 31) [6]
label("delay_high")
nop() [29]
jmp(x_dec, "delay_high")
# Turn off the LED and delay, taking 1000 cycles.
set(pins, 0)
set(x, 31) [6]
label("delay_low")
nop() [29]
jmp(x_dec, "delay_low")
# Create StateMachine(0) with the blink_1hz program, outputting on Pin(25).
sm = rp2.StateMachine(0, blink_1hz, freq=2000, set_base=Pin(25))
sm.active(1)
```
See the `examples/rp2/` directory for further example code.
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