I'm trying to understand the impact of using UART communication of the Raspberry's GPIO pins. So I'm reading the Raspberry UART documentation, but I'm not sure if I get everything right.
By default, on Raspberry Pis equipped with the wireless/Bluetooth module (Raspberry Pi 3 and Raspberry Pi Zero W), the PL011 UART is connected to the BT module
I'm not sure what "connected" means in this context. Because it says "by default", it seems to me that there are other options, potentially configurable, so it's just a software connection.
Later, the documentation says
pi3-disable-btdisables the Bluetooth device and restores UART0/ttyAMA0 to GPIOs 14 and 15.
So does "connected" mean that a) the bluetooth data is forwarded/copied to the PL011 UART (one-way)? Or b) does it also mean that writing to the GPIO pins will send data over bluetooth (two-way)? Or c) the connection between Bluetooth and UART on GPIO pins is an exclusive one. You could either use Bluetooth or use UART.
Last, I have a question on the sentence
pi3-miniuart-btswitches the Raspberry Pi 3 and Raspberry Pi Zero W Bluetooth function to use the mini UART (ttyS0), and restores UART0/ttyAMA0 to GPIOs 14 and 15.
in combination with
The particular deficiencies of the mini UART compared to the PL011 are : [...] [long list of disadvantages]
Since I need Bluetooth and UART, this seems to be the right option to me. Does Bluetooth work really fine using the Mini-UART? I definitely don't like to have Bluetooth issues.
I don't consider the suggested duplicate How do I make serial work on the Raspberry Pi3 , Pi3B+, PiZeroW as a duplicate, because
a) my question is about the impact, not on how to make it work.
The /dev/ttyAMA0 previously used to access the UART now connects to Bluetooth.
is something I already know (mentioned above), except for the term "connect", which is also not defined in the answers.
Unfortunately there are a number of other consequences: [...]
which are already listed in the official documentation which I linked to.
if you want to change the blutooth to miniuart port(bad)
just says "it's bad", but does not define how bad it is.