Mic API
********

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Function
---------

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Usage
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.. code:: python

	from m5stack import *
	import machine, _thread

	mic_adc = 0
	buffer = []
	def microphone_enter():
		print('microphone_enter')
	global mic_adc, buffer
  		try:
  			mic_adc = machine.ADC(34)
  			mic_adc.atten(mic_adc.ATTN_11DB)
    		dac = machine.DAC(machine.Pin(25))
    		dac.write(0)
  		except:
  			pass
  		buffer = []
  		for i in range(0, 55):
  			buffer.append(0)


	def microphone_loop():
		global mic_adc, buffer
  		val = 0
  		for i in range(0, 32):
  			raw = (mic_adc.readraw() - 1845) // 10
    		if raw > 20:
      			raw = 20
    		elif raw < -20:
      			raw = -20
    		val += raw
    	val = val // 32
  		buffer.pop()
  		buffer.insert(0, val)
  		for i in range(1, 50):
    		lcd.line(i*2+44, 120+buffer[i+1], i*2+44+2, 120+buffer[i+2], lcd.WHITE)
    		lcd.line(i*2+44, 120+buffer[i],   i*2+44+2, 120+buffer[i+1], lcd.BLACK)

	microphone_enter()

	while 1:
		microphone_loop()