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docs/rp2/quickref.rst: Add section on PIO.

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NitiKaur 2021-11-05 15:46:35 +05:30 committed by Damien George
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@ -92,6 +92,37 @@ Use the :ref:`machine.Pin <machine.Pin>` class::
p4 = Pin(4, Pin.IN, Pin.PULL_UP) # enable internal pull-up resistor
p5 = Pin(5, Pin.OUT, value=1) # set pin high on creation
Programmable IO (PIO)
---------------------
PIO is useful to build low-level IO interfaces from scratch. See the :mod:`rp2` module
for detailed explaination of the assembly instructions.
Example using PIO to blink an LED at 1Hz::
from machine import Pin
import rp2
@rp2.asm_pio(set_init=rp2.PIO.OUT_LOW)
def blink_1hz():
# Cycles: 1 + 7 + 32 * (30 + 1) = 1000
set(pins, 1)
set(x, 31) [6]
label("delay_high")
nop() [29]
jmp(x_dec, "delay_high")
# Cycles: 1 + 7 + 32 * (30 + 1) = 1000
set(pins, 0)
set(x, 31) [6]
label("delay_low")
nop() [29]
jmp(x_dec, "delay_low")
# Create and start a StateMachine with blink_1hz, outputting on Pin(25)
sm = rp2.StateMachine(0, blink_1hz, freq=2000, set_base=Pin(25))
sm.active(1)
UART (serial bus)
-----------------