def interrupt(self, callback, pin, interrupt_trigger=None, timeout=0):
"""Init interrupt callback function for pin.
Args:
callback (function): function to call on interrupt
pin (int): the pin to monitor for interrupts
"""
with self._gpio_lock:
gpio_pin = GPIO(pin, "preserve")
if gpio_pin.supports_interrupts:
gpio_pin.direction = "in"
gpio_pin.edge = interrupt_trigger
if gpio_pin.poll(timeout):
# Enter callback function
pass
gpio_pin.edge = "none" #need to set to none inorder to reuse pin for anything else
else:
self.logger.error(
"GPIO pin {} does not support interrupts".format(pin))
self.logger.debug(
"Set interrupt callback of GPIO pin {}".format(pin))
class Launcher(object):
"""Stores data coming from PRU's in HDF5 format
Args:
pin_button (int): Pin number where button is connected. Must be
configured as input with pull up and connected against ground
pin_led (int): Pin number of LED for displaying launcher status
service_name (str): Name of shepherd systemd service
"""
def __init__(
self,
pin_button: int = 81,
pin_led: int = 9,
service_name: str = "shepherd",
):
self.pin_button = pin_button
self.pin_led = pin_led
self.service_name = service_name
def __enter__(self):
self.gpio_led = GPIO(self.pin_led, "out")
self.gpio_button = GPIO(self.pin_button, "in")
self.gpio_button.edge = "falling"
logger.debug("configured gpio")
sysbus = dbus.SystemBus()
systemd1 = sysbus.get_object("org.freedesktop.systemd1",
"/org/freedesktop/systemd1")
self.manager = dbus.Interface(systemd1,
"org.freedesktop.systemd1.Manager")
shepherd_object = self.manager.LoadUnit(
f"{ self.service_name }.service")
self.shepherd_proxy = sysbus.get_object("org.freedesktop.systemd1",
str(shepherd_object))
logger.debug("configured dbus for systemd")
return self
def __exit__(self, *exc):
self.gpio_led.close()
self.gpio_button.close()
def run(self) -> NoReturn:
"""Infinite loop waiting for button presses.
Waits for falling edge on configured button pin. On detection of the
edge, shepherd service is either started or stopped. Double button
press while idle causes system shutdown.
"""
while True:
logger.info("waiting for falling edge..")
self.gpio_led.write(True)
if not self.gpio_button.poll():
# note: poll is suspected to exit after ~ 1-2 weeks running -> fills mmc with random measurement
# TODO: observe behavior, hopefully this change fixes the bug
continue
self.gpio_led.write(False)
logger.debug("edge detected")
if not self.get_state():
time.sleep(0.25)
if self.gpio_button.poll(timeout=5):
logging.debug("falling edge detected")
logging.info("shutdown requested")
self.initiate_shutdown()
self.gpio_led.write(False)
time.sleep(3)
continue
self.set_service(not self.get_state())
time.sleep(10)
def get_state(self, timeout: float = 10) -> bool:
"""Queries systemd for state of shepherd service.
Args:
timeout (float): Time to wait for service state to settle
Raises:
TimeoutError: If state remains changing for longer than timeout
"""
ts_end = time.time() + timeout
while True:
systemd_state = self.shepherd_proxy.Get(
"org.freedesktop.systemd1.Unit",
"ActiveState",
dbus_interface="org.freedesktop.DBus.Properties",
)
if systemd_state in ["deactivating", "activating"]:
time.sleep(0.1)
continue
else:
break
if time.time() > ts_end:
raise TimeoutError("Timed out waiting for service state")
logger.debug(f"service ActiveState: { systemd_state }")
if systemd_state == "active":
return True
elif systemd_state == "inactive":
return False
raise Exception(f"Unknown state { systemd_state }")
def set_service(self, requested_state: bool):
"""Changes state of shepherd service.
Args:
requested_state (bool): Target state of service
"""
active_state = self.get_state()
if requested_state == active_state:
logger.debug("service already in requested state")
self.gpio_led.write(active_state)
return
if active_state:
logger.info("stopping service")
self.manager.StopUnit("shepherd.service", "fail")
else:
logger.info("starting service")
self.manager.StartUnit("shepherd.service", "fail")
time.sleep(1)
new_state = self.get_state()
if new_state != requested_state:
raise Exception(f"state didn't change")
return new_state
def initiate_shutdown(self, timeout: int = 5) -> NoReturn:
""" Initiates system shutdown.
Args:
timeout (int): Number of seconds to wait before powering off
system
"""
logger.debug("initiating shutdown routine..")
time.sleep(0.25)
for _ in range(timeout):
if self.gpio_button.poll(timeout=0.5):
logger.debug("edge detected")
logger.info("shutdown cancelled")
return
self.gpio_led.write(True)
if self.gpio_button.poll(timeout=0.5):
logger.debug("edge detected")
logger.info("shutdown cancelled")
return
self.gpio_led.write(False)
os.sync()
logger.info("shutting down now")
self.manager.PowerOff()