import pyb
from pyb import Timer
import micropython
import stm

# Use with pyb.freq(96000000) and prescaler=11 for .25 usec timer ticks.
xfmr_pulse_period = 1200  # (= usec * 4)   Same as toggle_half_cycle duration.
xfmr_pulse_w = 300                           # (= usec * 4)

max_push_pulls = 8


def force_inactive1():
    # Put (t2ch2/t2ch1) mode to FORCED_INACTIVE to start...
    # TODO which isn it, ch1 or ch2?
    # TODO link to PDF and page number for register field description
    ccmr1 = stm.mem16[stm.TIM2 + stm.TIM_CCMR1]
    ccmr1 &= 0b1111111110001111  # OC2M "100"....OC1M "100"
    ccmr1 |= 0b0000000001000000
    stm.mem16[stm.TIM2 + stm.TIM_CCMR1] = ccmr1


def force_inactive2():
    # Put (t2ch2/t2ch1) mode to FORCED_INACTIVE to start...
    # TODO which isn it, ch1 or ch2?
    # TODO link to PDF and page number for register field description
    ccmr1 = stm.mem16[stm.TIM2 + stm.TIM_CCMR1]
    ccmr1 &= 0b1000111111111111  # OC2M "100"....OC1M "100"
    ccmr1 |= 0b0100000000000000
    stm.mem16[stm.TIM2 + stm.TIM_CCMR1] = ccmr1


def force_inactive():
    # Put t2ch2  t2ch1 mode to FORCED_INACTIVE to start...
    ccmr1 = stm.mem16[stm.TIM2 + stm.TIM_CCMR1]
    ccmr1 &= 0b1000111110001111  # OC2M "100"....OC1M "100"
    ccmr1 |= 0b0100000001000000
    stm.mem16[stm.TIM2 + stm.TIM_CCMR1] = ccmr1

def force_active():
    # TODO what to put here?


micropython.alloc_emergency_exception_buf(100)

events = 0
events_max_push_pulls = max_push_pulls


def disable_me(the_active_timer):
    global events
    events += 1
    if events>events_max_push_pulls:
        force_inactive1()
        the_active_timer.deinit()

# Timer 2 to give .125 usec timer ticks counting up:
t2 = pyb.Timer(2, prescaler=11, period=xfmr_pulse_period, mode=Timer.CENTER)
t2ch2 = t2.channel(2, pyb.Timer.PWM,  pulse_width=xfmr_pulse_w,
                   polarity=pyb.Timer.HIGH, pin=pyb.Pin.board.JP26)
t2ch1 = t2.channel(1, pyb.Timer.PWM_INVERTED, pulse_width=xfmr_pulse_period - xfmr_pulse_w,
                   polarity=pyb.Timer.LOW, pin=pyb.Pin.board.JP25)
t2ch1.callback(disable_me)