System Behavior
The image below shows the FloripaSat space system behavior.
Every time the systems resets, it will go through the boot process. In this mode the system is configuring the basics setting and buses. After that it should check if the antennas were deployed. Only at the first boot the system should go to the antenna deployment mode.
After a valid shutdown request telecommand the system will prepare itself to stop sending any RF signals for 24h. OBDH will warn TT&C and both will sleep for 24 hours. At the end both modules will reset itself and start the normal flow. EPS and payloads will stay unchanged.
After the setup, OBDH and TT&C will enter in the Antenna deployment mode. At first boot it's expected to both sleep for 45 minutes and then each module deploy all antennas. In the following reboots, both modules will skip this mode. The EPS will not enter in this mode.
In the normal mode, the system will act based in the energy level of the satellite. The level of energy will change the behavior of the following tasks:
- (BTI) Beacon signal Transmission Interval.
- (GTR) Enable/Disable General Telecommands Reception
- (TTI) Transceiver periodic telemetry signal Transmission Interval
- (PE) Enable/Disable Payloads Experiment
- (ROA) Turn on/off Regulators of OBDH, Antenna module
The levels of energy and the tasks behaviors are described as follow:
| Level | BTI | GTR | TTI | PE | ROA |
|---|---|---|---|---|---|
| L1 | 10s | on | 60s | on | on |
| L2 | 10s | on | 60s | off | on |
| L3 | 20s | on | 120s | off | on |
| L4 | 30s | on | off | off | on |
| L5 | 30s | off | off | off | off |
In summary: after launch the cubesat will do a quick setup on its modules: serial communication initialization, peripherals configurations and etc. Then the system will enter in the antenna release mode, waiting 45 minutes to deploy the antennas. After a successful deployment, the normal mode starts. And stays there if none of these two events happens: Receive a telecommand, or burn in reentry. Normal mode behavior is defined by energy level of the batteries where L1 means that the battery charge is high and every task is on and/or at its peak, L5 means that the battery charge is completely empty and the system is in low energy mode. The other intermediaries levels are described in the table above. Receiving telecommands can lead to a shutdown mode. Burn in reentry means the end of FloripaSat mission.
OBS 1: General Telecommands are any telecommand expect the shutdown command. Meaning that the cubesat will answer only to the telecommand shutdown request when the system is at the Normal mode with the L4 energy level.
OBS 2: The transceiver has a periodic transmission of the last readed data packet of the satellite. The interval is defined in the energy levels table above. This guaranteed that even if we fail at telecommand reception, the cubesat will transmit part of its data to the earth.