This week (or maybe next) i want to start developing a test version of the "find me" - mode.
As i mentioned before in another thread:
There might be three lightweight (max ~2g) solutions:This will be a great feature because the CF is so small that it's hard to find outside. I'm not the only one wo lost this crazy little thing.
1) Make sound with the motors using another PWM frequency (in between 5 - 8kHz) -> 0g additionally
This "come find me mode" should be activated if the connection is lost. The motors should shutdown when the voltage reaches ~3050mV to prevent a cut-off.
After the shutdown the voltage is raising, now the PWM should be activated to make the search mode running.
Would be also a nice idea to make music during the fly (changing PWM frequency for sound and PWM duty cycle for motor speed).
- Motor shutdown @ ~3050mV (@3000mV -> cut-off)
- Start the soundmaking PWM (one frequency beep for finding, EDIT: Loudest sound @res. freq. e.g. 6kHz) with a duty cycle of ~ 15%
I've looked in the crazyflie firmware sourcecode and i think it is not hard to add a mode where the PWM frequency is not 140kHz but e.g. 6kHz. I have to change (add new definitions in motors.h) the MOTORS_PWM_BITS to 10 and the MOTORS_PWM_PRESCALE to 16. In motors.c i will add a function with sets the frequency and starts this. I don't know in wich part but i have to check the battery and then start the function (maybe somebody knows where to put that).
I want to start to develop the firmware but i have one question: What happens if there is a bug or mistake in the firmware? Is the bootloader always the same that I can upload all what i want without damage effect? (I want to use the wireless bootloader -> no JTAG environment available).
2) Hack a key finder (http://loc8tor.com/) -> ~$44 & 2g when hacked (~6g with case etc)
foosel had that idea, look here: Link to post
3) Add a piezzo for making a loud sound (~60 up to 80dB) -> adds about 1-2g, connected to extension header
I tried to find a lightweight piezzo but its not that easy. They also costs about 4€ which is not that less. Maybe someone found a good, cheap and lightweight one.
Hopefully we find a solution, because a lost crazyflie is a lost one.