## 基于PICO学习板的快速参考指南
{{:pico_learningkit_functions.png|}}<WRAP centeralign> PICO学习板功能及对应的管脚</WRAP>

#### 1. 通用的板卡控制
<code python>
import pyb

pyb.repl_uart(pyb.UART(1, 9600)) # duplicate REPL on UART(1)
pyb.wfi() # pause CPU, waiting for interrupt
pyb.freq() # get CPU and bus frequencies
pyb.freq(60000000) # set CPU freq to 60MHz
pyb.stop() # stop CPU, waiting for external interrupt
</code>

#### 2. 延迟和定时

<code python>
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 value of millisecond counter
delta = time.ticks_diff(time.ticks_ms(), start) # compute time difference
</code>


#### 3. LEDs

<code python>
from machine import Pin

led_y = Pin(20,Pin.OUT)  
led_r = Pin(26,Pin.OUT)  
led_g = Pin(22,Pin.OUT)  
led_b = Pin(21,Pin.OUT)  

</code>


#### 4. 板上按键

<code python>
import machine

key1 = machine.Pin(12, machine.Pin.IN, machine.Pin.PULL_UP)
key2 = machine.Pin(13, machine.Pin.IN, machine.Pin.PULL_UP)
</code>


#### 5. 管脚和GPIO

<code python>
from pyb import Pin

p_out = Pin('X1', Pin.OUT_PP)
p_out.high()
p_out.low()

p_in = Pin('X2', Pin.IN, Pin.PULL_UP)
p_in.value() # get value, 0 or 1
</code>


#### 6. 定时器

<code python>
from pyb import Timer

tim = Timer(1, freq=1000)
tim.counter() # get counter value
tim.freq(0.5) # 0.5 Hz
tim.callback(lambda t: pyb.LED(1).toggle())
</code>


#### 7. PWM

<code python>
import machine
import utime
beep = machine.PWM(machine.Pin(22))
beep.freq(1000)   #频率
while True:
     beep.duty_u16(100)  #改变占空比改变蜂鸣器的响度

</code>


#### 8. ADC

<code python>
from pyb import Pin, ADC

adc = ADC(Pin('X19'))
adc.read() # read value, 0-4095
</code>


#### 9. UART

<code python>
from pyb import UART

uart = UART(1, 9600)
uart.write('hello')
uart.read(5) # read up to 5 bytes
</code>


#### 10. SPI总线

<code python>
from pyb import SPI

spi = SPI(1, SPI.CONTROLLER, baudrate=200000, polarity=1, phase=0)
spi.send('hello')
spi.recv(5) # receive 5 bytes on the bus
spi.send_recv('hello') # send and receive 5 bytes
</code>


#### 11. I2C总线

<code python>
from machine import I2C

i2c = I2C('X', freq=400000)                 # create hardware I2c object
i2c = I2C(scl='X1', sda='X2', freq=100000)  # create software I2C object

i2c.scan()                          # returns list of peripheral addresses
i2c.writeto(0x42, 'hello')          # write 5 bytes to peripheral with address 0x42
i2c.readfrom(0x42, 5)               # read 5 bytes from peripheral

i2c.readfrom_mem(0x42, 0x10, 2)     # read 2 bytes from peripheral 0x42, peripheral memory 0x10
i2c.writeto_mem(0x42, 0x10, 'xy')   # write 2 bytes to peripheral 0x42, peripheral memory 0x10

</code>


#### 12. 姿态传感器

<code python>
from pyb import Accel

accel = Accel()
print(accel.x(), accel.y(), accel.z(), accel.tilt())
</code>


#### 13. WS2812B控制

<code python>

</code>


#### 14. 蜂鸣器的控制

<code python>
from machine import Pin, PWM
from utime import sleep

buzzer = PWM(Pin(22))
buzzer.freq(500)
buzzer.duty_u16(1000)
sleep(1)
buzzer.duty_u16(0)
</code>