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:
Running MicroPython¶
See the corresponding section of the tutorial: Getting started with MicroPython on the ESP8266.
Delay and timing¶
Use the 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 machine.Pin class:
from machine import Pin
pin = Pin(("gpiob", 21), Pin.IN) # create input pin on GPIO port B
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(("gpiob", 21), Pin.IN) # create input pin on GPIO port B
pin = Pin(("gpiob", 21), Pin.OUT, value=1) # set pin high on creation
pin = Pin(("gpiob", 21), Pin.IN, Pin.PULL_UP) # enable internal pull-up resistor
switch = Pin(("gpioc", 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 machine.I2C class:
from machine import I2C
i2c = I2C("i2c0") # 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 machine.SPI class:
from machine import SPI
spi = SPI("spi0") # 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("spi0", 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 zephyr.DiskAccess class to support filesystem:
import vfs
from zephyr import DiskAccess
block_dev = DiskAccess('SDHC') # create a block device object for an SD card
vfs.VfsFat.mkfs(block_dev) # create FAT filesystem object using the disk storage block
vfs.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 zephyr.FlashArea class to support filesystem:
import vfs
from zephyr import FlashArea
block_dev = FlashArea(4, 4096) # creates a block device object in the frdm-k64f flash scratch partition
vfs.VfsLfs2.mkfs(block_dev) # create filesystem in lfs2 format using the flash block device
vfs.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 zsensor.Sensor class to access sensor data:
import zsensor
from zsensor import Sensor
accel = Sensor("fxos8700") # 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