import machine
import utime
import rp2

@rp2.asm_pio(set_init=(rp2.PIO.OUT_LOW,rp2.PIO.OUT_LOW,rp2.PIO.OUT_LOW))
def blink():
    wrap_target()
    
    set(pins, 0b101)              [14]
    set(x, 30)
    # 循环次数：(30+1) * (32+32) = 1984
    label('high_loop')
    nop() [31]
    jmp(x_dec, 'high_loop')   [31]
    
    set(pins, 0b010)              [13]  
    set(x, 30)
    # 循环次数：(30+1) * (32+32) = 1984
    label('low_loop')
    nop() [31]
    jmp(x_dec, 'low_loop')   [31]
    
    irq(rel(0))
    wrap()

sm = rp2.StateMachine(0, blink, freq=2000, set_base=machine.Pin(18))

def elapsed_time_handler(pin):
    global start
    end = utime.ticks_us()
    print(utime.ticks_diff(end, start))
    start = end

sm.irq(elapsed_time_handler)

start = utime.ticks_us()
sm.active(1)