Hi
@BearBu how do u find the FM transmitter in your picture? I've tried this one, i was going to just power it with a USB port, it works but the signal is relatively weak and I can hear static, which is obviously annoying if I'm trying to play music or anything requiring some quality of audio. Does the one in your picture sounds better without static? I don't want to keep buying more FM dongles to be disappointed.
Also, the FM module itself is an oem module, I'm wondering if it's feeding analogue audio signal back into the MCU... If not directly behind the mcu, there'll be a stereo signal somewhere within the FM receiver module itself, someone like you might be in the best position to test the pinouts to see if it's possible to feed a signal directly wired in... I remember working on my Porsche that came with a MOST waveguide AMP and it was a biatch to feed AUX signal into.. Until I took apart the AMP and found the ribbon cable linking the 2 circuit board halves, one half was the MOST decoder and the other half was the actual AMP, so i played some music and used a multimeter and a headphone to figure out which pin was which, then soldered a standard 3.5mm aux port to the 3 cables representing FL, FR and GND... I'm wondering if the Tesla uses similar architecture, since the FM module is also a Bosche unit from what i can tell online...