There's a protobuf-based API for two-way communication between the Android Auto app and the head unit [0]. It depends on what the headunit supports, but this includes data such as GPS location, steering wheel button activation, accelerometer data, parking brake activation, gear selection, touch screen input, dimmer switch position, odometer, and much more.
replyA lot of this has obvious use within the AA interface; for example, the parking brake position is used to prevent scrolling too far through lists, and the car's GPS is usually much more accurate than the phone's and better on the phone battery.
0: https://github.com/f1xpl/aasdk/tree/development/aasdk_proto (pretty old reverse-engineering effort)
One of the things I notice CarPlay has access to is the fan speed. In one of my vehicles, when I say “hey siri” it turns the HVAC fan down so it can hear me better. I’ve always wondered if the interface is the phone telling the car “hey make things quieter” or if it’s explicitly turning the fan down. It’s also interesting that this only happens in one of my cars. I assume it’s because the other car is a higher end vehicle and has a quieter fan.
replyIn GM cars (as observed in my last few), the logic is in the head unit: "mic on -> hvac lower", while "hotword detect" uses a different "mic on" method that does not
replyEDIT, previously "does not" above said "doe snot", which explains the reply below
I'm sure it's not great, but deer mucus is a bit of an extreme description.
replyI appreciate this comment, FWIW.
replyI never learned to properly touch type, i have my own method, somehow, which uses two fingers of the left hand and three of the right. Spacebar being pressed too soon or too late is, sadly, common :(
replyProper touch typing doesn't fix that issue.
replyThat icon is a "close Carplay/Auto" button. My Subaru has a Subaru button; my wife's Mazda has a Mazda button.
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