Fafnir

Propulsion Engine Controller

Prerequisites

Follow zephyr getting started guide

Build

cd zephyr-firmware
west update
cd fafnir
west build -b fafnir app --pristine
west flash

Build for native simulation

docker run -ti -v /Volumes/external/zephyrproject/:/workdir -v /Volumes/external/aesir/Fafnir/zephyr-firmware/:/app ghcr.io/zephyrproject-rtos/zephyr-build:main
cd /app/fafnir
west build -b native_sim/native/64 app --pristine -- -DEXTRA_CONF_FILE=debug.conf
./build/zephyr/zephyr.exe

or

west build -b native_sim/native/64 app -- -DEXTRA_CONF_FILE=debug.conf && ./build/zephyr/zephyr.exe

Using shell in simulation

You can send can messages like this

uart: ~$ can send can_loopback0 ID DATA

For example, running

uart: ~$ can send can_loopback0 123 0

will tell Fafnir to go into state STATE_INIT.

Running

uart: ~$ can send can_loopback0 124 0 1

will use the override feature to set N2 Valve HIGH.

CAN message specification to Fafnir

CAN ID	byte	data	type
0x123	0	launch sequence number (1-6)	uint8
0x124	0	Solenoid ID (1-4)	uint8
	1	1 == open, 0 == closed	bool

Note that the launch sequence number corresponds to the launch sequence number as given in https://aesir.slab.com/posts/mjollnir-launch-sequence-2juh5ekp

Note that the Solenoid ID corresponds to the solenoid ports on the Fafnir board. Mjollnir only has two solenoids which correspond to:

Solenoid ID 2 => Bypass valve
Solenoid ID 3 => Pilot valve
Solenoid ID 4 => Control vent

Solenoid IDs 1 and 4 are not connected and don't do anything.

CAN acknowledges

CAN ID	byte	data	meaning
0x125	0	0x01	Changing state!
	1	<byte>	the state we're changing to
0x125	0	0x02	Received valid override command!
	1	<byte>	The first byte we received
	2	<byte>	The second byte we received
0x125	0	0xF0	Recieved invalid state
0x125	0	0xF1	Cannot perform ignition command while attempting ignition. (Protection against double send)
	1	<byte>	State command we received
0x125	0	0xF2	Invalid state command
0x125	0	0xF3	Invalid override command
0x125	0	0xF4	Invalid pin given in override command

The state we're changing to is of type equal to this C enum:

typedef enum {
    STATE_IDLE,
    STATE_INIT,
    STATE_FILL,
    STATE_STOP_FILL,
    STATE_UMBILICAL,
    STATE_N2_PRESSURIZATION,
    STATE_IGNITION_1,
    STATE_IGNITION_2,
    STATE_IGNITION_3,
    STATE_IGNITION_4,
    STATE_SAFE,
    STATE_ABORT_BEFORE_COUNTDOWN,
    STATE_ABORT_AFTER_COUNTDOWN
} State_t;

Note that this is NOT the same as the launch sequence number used in the command above (0x123).