ESP32 MicroPython WiFi Geiger Counter (Work in Progress)

esp32-micropython-wifi-geiger-counter.py

import network
from machine import Pin, Timer, PWM
import utime

wlan = network.WLAN(network.STA_IF)
wlan.active(True)

speaker = Pin(26, Pin.OUT)
MY_SSID = "attwifi"
my_rssi = 0

tick_timer = Timer(0)  ## Hardware timer
#tick_timer = Timer(-1)  ## Virtual RTOS-based software timer

def tick_spkr(timer):
  speaker.on(); utime.sleep_ms(5); speaker.off()

def scan():
  # FIXME: wlan scan freezes timer while scanning
  nets = wlan.scan()

  global my_rssi
  found_my_ssid = False
  
  for net in nets:
    ssid = net[0].decode('utf-8')
    ch = net[2]
    rssi = net[3]
  
    print( 'Ch {0:2}  RSSI {1}  SSID {2}'.format(ch, rssi, ssid) )
  
    if ssid == MY_SSID:
      found_my_ssid = True
      my_rssi = rssi
	  
  if found_my_ssid == True:
    sig_period = ((abs(my_rssi) - 30) + 8)**2  ## best sig = -30
    
    # FIXME: Is this the only way to change the timer period?
    tick_timer.init(period=sig_period, mode=Timer.PERIODIC, callback=tick_spkr)
    
    print('My network found! {}'.format(sig_period) )
  else:
    tick_timer.deinit()


while True:
  scan()