cfc212b108
This commit implements fairly complete support for the DMA controller in
the rp2 series of microcontrollers. It provides a class for accessing the
DMA channels through a high-level, Pythonic interface, and functions for
setting and manipulating the DMA channel configurations.
Creating an instance of the rp2.DMA class claims one of the processor's DMA
channels. A sensible, per-channel default value for the ctrl register can
be fetched from the DMA.pack_ctrl() function, and the components of this
register can be set via keyword arguments to pack_ctrl().
The read, write, count and ctrl attributes of the DMA class provide
read/write access to the respective registers of the DMA controller. The
config() method allows any or all of these values to be set simultaneously
and adds a trigger keyword argument to allow the setup to immediately be
triggered. The read and write attributes (or keywords in config()) accept
either actual addresses or any object that supports the buffer interface.
The active() method provides read/write control of the channel's activity,
allowing the user to start and stop the channel and test if it is running.
Standard MicroPython interrupt handlers are supported through the irq()
method and the channel can be released either by deleting it and allowing
it to be garbage-collected or with the explicit close() method.
Direct, unfettered access to the DMA controllers registers is provided
through a proxy memoryview() object returned by the DMA.registers attribute
that maps directly onto the memory-mapped registers. This is necessary for
more fine-grained control and is helpful for allowing chaining of DMA
channels.
As a simple example, using DMA to do a fast memory copy just needs:
src = bytearray(32*1024)
dest = bytearray(32*1024)
dma = rp2.DMA()
dma.config(read=src, write=dest, count=len(src) // 4,
ctrl=dma.pack_ctrl(), trigger=True)
# Wait for completion
while dma.active():
pass
This API aims to strike a balance between simplicity and comprehensiveness.
Signed-off-by: Nicko van Someren <nicko@nicko.org>
Signed-off-by: Damien George <damien@micropython.org>
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.
timemodule with sleep, time and ticks functions.osmodule with VFS support.machinemodule with the following classes:Pin,ADC,PWM,I2C,SPI,SoftI2C,SoftSPI,Timer,UART,WDT.rp2module 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 submodules
$ 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.
If you are using a different board other than a Rasoberry Pi Pico, then you should pass the board name to the build; e.g. for Raspberry Pi Pico W:
$ make BOARD=RPI_PICO_W submodules
$ make BOARD=RPI_PICO_W clean
$ make BOARD=RPI_PICO_W
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.
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.
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.