Startup

The way core is initialized and how it initializes other submodules

Description

When the core.start method is called, the first action core will take is to attempt to call the start method for each submodule in core.submodules. Calling the start method for each submodule is different from creating an instance of that submodule. Instantiating submodule objects are done in the core.__init__ constructor method.

core.start follows this sequence:

• for the submodules listed in config['core']['modules']['A']

  • if the submodule has a start method, call the start method

• verify that the system is booting up for the first time

  • if the system is booting for the first time, sleep for 30 minutes

• for the submodules listed in config['core']['modules']['B']

  • if the submodule has a start method, call the start method

• set core.state to mode.NORMAL_MODE

• verify that the system has sufficient power to enter NORMAL_MODE

  • if the system does not have sufficient power, sleep until sufficient power is reached

• for the submodules listed in config['core']['modules']['C']

  • if the submodule has a start method, call the start method

• for the processes in core.processes

  • start the process

Startup Sequence

In config/config_default.yml, submodules are listed under A, B, and C headers. A modules are started first, followed by B modules, followed by C modules.

• start the A modules

• sleep for 30 minute if first boot

• start the B modules

• sleep until sufficient power is reached

• start the C modules

Checking for first boot

As per regulation, the CUBESAT must sleep for 30 minutes after it boots for the first time. This check is done using the following method:

On *nix systems, like the Raspberry Pi Zero W, there is a command called last reboot which stores records of all the reboots. is_first_boot utilizes this system command to check if it is booting up for the first time

def is_first_boot() -> bool:
    """
    Returns True if it is determined that the computer is booting for the first time
    """
    cmd = subprocess.Popen(['last', 'reboot'], stdout=subprocess.PIPE, stderr=None)
    reboot_num = len([x for x in cmd.communicate()[0].splitlines() if x])-1
    return reboot_num == 1 

Checking for sufficient power

This is just a While loop that constantly queries eps until it reports a sufficient power level

while self.submodules['eps'].get_battery_bus_volts() < Power.STARTUP.value:
    time.sleep(1)
self.mode = Mode.NORMAL