.. _zephyr_quickref: Quick reference for the Zephyr port =================================== Below is a quick reference for the Zephyr port. If it is your first time working with this port please consider reading the following sections first: .. toctree:: :maxdepth: 1 general.rst tutorial/index.rst Running MicroPython ------------------- See the corresponding section of the tutorial: :ref:`intro`. Delay and timing ---------------- Use the :mod:`time ` module:: import time time.sleep(1) # sleep for 1 second time.sleep_ms(500) # sleep for 500 milliseconds time.sleep_us(10) # sleep for 10 microseconds start = time.ticks_ms() # get millisecond counter delta = time.ticks_diff(time.ticks_ms(), start) # compute time difference Pins and GPIO ------------- Use the :ref:`machine.Pin ` class:: from machine import Pin pin = Pin(("GPIO_1", 21), Pin.IN) # create input pin on GPIO1 print(pin) # print pin port and number pin.init(Pin.OUT, Pin.PULL_UP, value=1) # reinitialize pin pin.value(1) # set pin to high pin.value(0) # set pin to low pin.on() # set pin to high pin.off() # set pin to low pin = Pin(("GPIO_1", 21), Pin.IN) # create input pin on GPIO1 pin = Pin(("GPIO_1", 21), Pin.OUT, value=1) # set pin high on creation pin = Pin(("GPIO_1", 21), Pin.IN, Pin.PULL_UP) # enable internal pull-up resistor switch = Pin(("GPIO_2", 6), Pin.IN) # create input pin for a switch switch.irq(lambda t: print("SW2 changed")) # enable an interrupt when switch state is changed Hardware I2C bus ---------------- Hardware I2C is accessed via the :ref:`machine.I2C ` class:: from machine import I2C i2c = I2C("I2C_0") # construct an i2c bus print(i2c) # print device name i2c.scan() # scan the device for available I2C slaves i2c.readfrom(0x1D, 4) # read 4 bytes from slave 0x1D i2c.readfrom_mem(0x1D, 0x0D, 1) # read 1 byte from slave 0x1D at slave memory 0x0D i2c.writeto(0x1D, b'abcd') # write to slave with address 0x1D i2c.writeto_mem(0x1D, 0x0D, b'ab') # write to slave 0x1D at slave memory 0x0D buf = bytearray(8) # create buffer of size 8 i2c.writeto(0x1D, b'abcd') # write buf to slave 0x1D Hardware SPI bus ---------------- Hardware SPI is accessed via the :ref:`machine.SPI ` class:: from machine import SPI spi = SPI("SPI_0") # construct a spi bus with default configuration spi.init(baudrate=100000, polarity=0, phase=0, bits=8, firstbit=SPI.MSB) # set configuration # equivalently, construct spi bus and set configuration at the same time spi = SPI("SPI_0", baudrate=100000, polarity=0, phase=0, bits=8, firstbit=SPI.MSB) print(spi) # print device name and bus configuration spi.read(4) # read 4 bytes on MISO spi.read(4, write=0xF) # read 4 bytes while writing 0xF on MOSI buf = bytearray(8) # create a buffer of size 8 spi.readinto(buf) # read into the buffer (reads number of bytes equal to the buffer size) spi.readinto(buf, 0xF) # read into the buffer while writing 0xF on MOSI spi.write(b'abcd') # write 4 bytes on MOSI buf = bytearray(4) # create buffer of size 8 spi.write_readinto(b'abcd', buf) # write to MOSI and read from MISO into the buffer spi.write_readinto(buf, buf) # write buf to MOSI and read back into the buf Disk Access ----------- Use the :ref:`zephyr.DiskAccess ` class to support filesystem:: import os from zephyr import DiskAccess block_dev = DiskAccess('SDHC') # create a block device object for an SD card os.VfsFat.mkfs(block_dev) # create FAT filesystem object using the disk storage block os.mount(block_dev, '/sd') # mount the filesystem at the SD card subdirectory # with the filesystem mounted, files can be manipulated as normal with open('/sd/hello.txt','w') as f: # open a new file in the directory f.write('Hello world') # write to the file print(open('/sd/hello.txt').read()) # print contents of the file Flash Area ---------- Use the :ref:`zephyr.FlashArea ` class to support filesystem:: import os from zephyr import FlashArea block_dev = FlashArea(4, 4096) # creates a block device object in the frdm-k64f flash scratch partition os.VfsLfs2.mkfs(block_dev) # create filesystem in lfs2 format using the flash block device os.mount(block_dev, '/flash') # mount the filesystem at the flash subdirectory # with the filesystem mounted, files can be manipulated as normal with open('/flash/hello.txt','w') as f: # open a new file in the directory f.write('Hello world') # write to the file print(open('/flash/hello.txt').read()) # print contents of the file Sensor ------ Use the :ref:`zsensor.Sensor ` class to access sensor data:: import zsensor from zsensor import Sensor accel = Sensor("FXOX8700") # create sensor object for the accelerometer accel.measure() # obtain a measurement reading from the accelerometer # each of these prints the value taken by measure() accel.get_float(zsensor.ACCEL_X) # print measurement value for accelerometer X-axis sensor channel as float accel.get_millis(zsensor.ACCEL_Y) # print measurement value for accelerometer Y-axis sensor channel in millionths accel.get_micro(zsensor.ACCEL_Z) # print measurement value for accelerometer Z-axis sensor channel in thousandths accel.get_int(zsensor.ACCEL_X) # print measurement integer value only for accelerometer X-axis sensor channel