myPWM.py

from machine import PWM,Pin,mem32


class  myPWM(PWM):
    def __init__(self,pin,divider=8,top=255):
        #ok check from new micropython
        #gpio id is now GPIOx instead of x
        pinstr = str(pin).split(',')[0]
        if pinstr.upper().find('GPIO') >=0 :
            self.id = int(pinstr[8:])
        else :
            self.id = int(pinstr[4:])
        self.A_B = self.id & 1
        self.channel = self.id >> 1
        self.divider = divider
        self.top = top
        
        super().__init__(pin)
        super().freq(122_000)
        super().duty_u16(32768)
        # set memory base
        self.PWM_BASE = 0x4005_0000 + (self.channel * 0x14)
        # set divider base
        self.PWM_DIV = self.PWM_BASE + 4
        # set  top base
        self.PWM_TOP = self.PWM_BASE + 16
        # set  cc base
        self.PWM_CC = self.PWM_BASE + 12
        
        #ok we want frequency around 60KHz and max top at 255
        # 125Mhz / (255 * 60000) => 8.1
        # then  125MHZ / ( 8 * 255) = 61275Hz
        
        # set divider to 8
        #mem32[self.PWM_DIV] =  8 << 4
        mem32[self.PWM_DIV] =  self.divider << 4
        # set top to 255
        mem32[self.PWM_TOP] =  self.top
        self.duty(self.top // 2)
        
        
    #def deinit(self):
    #    super().deinit()
    #    _p = Pin(self.id,Pin.IN)
        
    def duty(self, value):
        if value > self.top:
            value = self.top
        reg = mem32[self.PWM_CC]
        if self.A_B == 0:
            # ok change channel A
            mem32[self.PWM_CC]=  (reg & 0xffff0000) | value
        else:
            # channel channel B
            mem32[self.PWM_CC]= ( reg & 0xffff) | (value << 16)
            
            
if __name__ == "__main__":
    import utime
    pwm = myPWM(Pin(15))
    try:
        value = 0
        increment = 1
        while True:
            value = value % 256
            pwm.duty(value)
            if value == 0:
                increment = increment * (-1)
            value += increment
            utime.sleep_ms(1)
    except KeyboardInterrupt:
        pwm.deinit()