docs: Add quick reference page, with pinout and short example code.

docs/index.rst

@@ -5,6 +5,11 @@ Micro Python documentation and references
 
 Here you can find documentation for Micro Python and the pyboard.
 
+.. toctree::
+   :maxdepth: 1
+
+   quickref.rst
+
 Software
 --------
 

docs/quickref.rst

@@ -0,0 +1,127 @@
+Quick reference for the pyboard
+=====================================
+
+.. image:: http://micropython.org/static/resources/pybv10-pinout.jpg
+    :alt: AMP skin
+    :width: 600px
+
+General board control
+---------------------
+::
+
+    import pyb
+
+    pyb.delay(50) # wait 50 milliseconds
+    pyb.millis() # number of milliseconds since bootup
+    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
+
+LEDs
+----
+::
+
+    from pyb import LED
+
+    led = LED(1) # red led
+    led.toggle()
+    led.on()
+    led.off()
+
+Pins and GPIO
+-------------
+::
+
+    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
+
+External interrupts
+-------------------
+::
+
+    from pyb import Pin, ExtInt
+
+    callback = lambda e: print("intr")
+    ext = ExtInt(Pin('Y1'), ExtInt.IRQ_RISING, Pin.PULL_NONE, callback)
+
+Timers
+------
+::
+
+    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())
+
+PWM (pulse width modulation)
+----------------------------
+::
+
+    from pyb import Pin, Timer
+
+    p = Pin('X1') # X1 has TIM2, CH1
+    tim = Timer(2, freq=1000)
+    ch = tim.channel(1, Timer.PWM, pin=p)
+    ch.pulse_width_percent(50)
+
+ADC (analog to digital conversion)
+----------------------------------
+::
+
+    from pyb import Pin, ADC
+
+    adc = ADC(Pin('X19'))
+    adc.read() # read value, 0-4095
+
+DAC (digital to analog conversion)
+----------------------------------
+::
+
+    from pyb import Pin, DAC
+
+    dac = DAC(Pin('X5'))
+    dac.write(120) # output between 0 and 255
+
+UART (serial bus)
+-----------------
+::
+
+    from pyb import UART
+
+    uart = UART(1, 9600)
+    uart.write('hello')
+    uart.read(5) # read up to 5 bytes
+
+SPI bus
+-------
+::
+
+    from pyb import SPI
+
+    spi = SPI(1, SPI.MASTER, baudrate=200000, polarity=1, phase=0)
+    spi.send('hello')
+    spi.recv(5) # receive 5 bytes on the bus
+    spi.send_recv('hello') # send a receive 5 bytes
+
+I2C bus
+-------
+::
+
+    from pyb import I2C
+
+    i2c = I2C(1, I2C.MASTER, baudrate=100000)
+    i2c.scan() # returns list of slave addresses
+    i2c.send('hello', 0x42) # send 5 bytes to slave with address 0x42
+    i2c.recv(5, 0x42) # receive 5 bytes from slave
+    i2c.mem_read(2, 0x42, 0x10) # read 2 bytes from slave 0x42, slave memory 0x10
+    i2c.mem_write('xy', 0x42, 0x10) # write 2 bytes to slave 0x42, slave memory 0x10