Here's some example code for callback-based station scanning:
# import radio stuff
from FMRadio import FMRadio, FMRadioUnavailableError
stations = 
def scan_cb(freq, is_station):
Callback for scanning for stations. This callback is called for every
frequency and tells you if a radio station was found.
print "scanning @ %0.2f MHz" % (freq / 1000.0),
print "STATION FOUND"
# open the radio
radio = FMRadio()
# radio not available
print "Your device doesn't seem to have a FM radio..."
import sys; sys.exit(1)
# get frequency range; currently only the US/Europe frequency band is supported
# by the driver
low, high = radio.get_frequency_range()
print "Frequency range: %0.2f - %0.2f MHz" % (low / 1000.0, high / 1000.0)
# scan for radio stations
# if we have found some stations, start playing
print "Now listen to the radio."
for freq in stations:
print "Tuning in %0.2f MHz." % (freq / 1000.0)
import time; time.sleep(3)
print "No radio stations found. The signal is too weak."
# don't forget to shutdown the radio; this will also power down the radio chip
print "Switching off the radio."