import time
from machine import Pin, Timer
from rp2 import asm_pio, StateMachine, PIO


PWM_Frequency_Hz     = 500
PWM_Duty_Step        = 10
PWM_Duty_Min         = 10
PWM_Duty_Max         = 100
PWM_Duty_Num_Samples = 10

DataPin  = Pin(15, Pin.OUT)
ClockPin = Pin(19, Pin.OUT)
LatchPin = Pin(18, Pin.OUT)


mduty = 0
timer = 0
pindex = 0
mindex  = 0
t3 = 0
t4 = 0




@asm_pio( out_shiftdir=PIO.SHIFT_RIGHT,
          autopull=True, pull_thresh=8,
          out_init=(PIO.OUT_LOW),
          sideset_init=(PIO.OUT_LOW,PIO.OUT_LOW) )

def send_out():
    wrap_target()
    set(x,7)          .side(0b00) # set X to 7 (use X as bit counter)
    # shift 8 bits out to the SCLK pin, LSB first
    label('loop')
    out(pins,1)       .side(0b00) # shift 1 bit from OSR to the first out pin
                                  # drive SCLK pin low
    jmp(x_dec,'loop') .side(0b10) # branch to loop if X is not zero, decrement X
                                  # drive SCLK pin high
    pull(ifempty)     .side(0b01) # get a word from TX-FIFO into OSR, stall if empty
                                  # drive LOAD pin high
    wrap()



sm = StateMachine(0, send_out, out_base=DataPin,
                 sideset_base=LatchPin, freq=1_000_000)
#sm = StateMachine(0, send_out, out_base=DataPin,
#                 sideset_base=LatchPin)

#             0    1    2    3    4    5    6    7    8    9       perc.  
pwm_values=[[0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00],   #   0
            [0x00,0x00,0x00,0x00,0x80,0x00,0x00,0x00,0x00,0x00],   #  10
            [0x00,0x00,0x80,0x00,0x00,0x00,0x00,0x80,0x00,0x00],   #  20
            [0x00,0x80,0x00,0x00,0x00,0x80,0x00,0x00,0x00,0x80],   #  30
            [0x80,0x00,0x80,0x00,0x00,0x00,0x80,0x00,0x80,0x00],   #  40
            [0x00,0x80,0x00,0x80,0x00,0x80,0x00,0x80,0x00,0x80],   #  50
            [0x00,0x80,0x00,0x80,0x80,0x80,0x00,0x80,0x00,0x80],   #  60
            [0x80,0x00,0x80,0x80,0x80,0x80,0x80,0x00,0x80,0x00],   #  70
            [0x80,0x00,0x80,0x80,0x80,0x80,0x80,0x80,0x00,0x80],   #  80
            [0x80,0x00,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80],   #  90
            [0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80]]   # 100

def pwm_pin(timer):
    global sm
    global mduty
    global pindex
    global pwm_values
    global mindex
    
    global t3
    global t4
    
    t3 = time.time_ns()
    duty_cycle = mduty

    #index = int(duty_cycle / PWM_Duty_Step)
    #print ("duty_cycle =",duty_cycle,"%,  index =", index)
    data = pwm_values[mindex][pindex]
    sm.put(data)
    #print (hex(data), end=" ")
    pindex = pindex + 1
    if pindex >= PWM_Duty_Num_Samples:
        pindex = 0

    t4 = time.time_ns()


def pwm_init(frequency):
    global mduty
    global timer
    global pindex
    global sm
    
    mduty = 0
    pindex = 0
    
    timer = Timer()
    timer.init(freq=(frequency * 10),mode=Timer.PERIODIC, callback=pwm_pin)  
    sm.active(1) # run the SM 
    


def pwm_deinit():  
    global timer
    global sm
    
    pwm_set(0)
    time.sleep(1)
    print ("deinit")
    sm.active(0)
    print ("Stop SM")
    print ("Deinit timer")
    if (timer != 0):
        timer.deinit()


        

def pwm_set(duty):
    global mduty
    global mindex
    
    mduty = duty
    mindex = int(duty / PWM_Duty_Step)
    


try:
    #PWM_Frequency_Hz
    
    pwm_init(PWM_Frequency_Hz)

    print("")
    print ("Start PWM PIO")
    t1 = time.time_ns()


    for d in range(PWM_Duty_Min, PWM_Duty_Max + PWM_Duty_Step, PWM_Duty_Step):
        #print ("duty =", d, "%") 
        pwm_set(d)
        time.sleep_ms(int(float(1.0/PWM_Frequency_Hz) * 1000.0))

    #pwm_set(10)
    #time.sleep(1)
    print ("Diff time t3/t4 ns timer = ", ((t4-t3)/1000.0), "us")
    

    t2 = time.time_ns()
    print("Start time = ", t1)
    print ("Stop time  = ",t2)
    print ("Diff time ns timer = ", ((t2-t1)/1000.0), "ms")
    print ("Stop  PWM PIO")
    pwm_deinit()
    print ("Finished")


except KeyboardInterrupt:
    pass
#finally:
    #sm.put(0x00)
    #time.sleep_ms(100)
    #sm.active(0)
    #time.sleep_ms(500)