I am working on a project which has a Raspberry Pi 3 Compute Module integrated into a hardware design where the PCB provides access to both Serial Ports on the compute module:
- One serial port with TX/RX on GPIO 14/15 (pins 51/53 of module)
- One serial port with CTS/RTS/TX/RX on GPIO 31/31/32/33 (pins 34/36/46/48 of the module)
As far as I understand there is one full 16650 compatible UART available in the BCM2835 called the "PL011", and one mini-UART which is normally used to communicate with the internal BlueTooth chip.
When booting Raspbian Jesse, I see the /dev/ttyAMA0 device which seems to communicate on GPIO pins 14/15, and according to what I have read this communication runs through the PL011 full UART chip. I have tried to create a /boot/config.txt file which has the following device tree overlays:
dtoverlay=uart1,txd1_pin=32,rxd1_pin=33
enable_uart=1
This does not seem to provide me with a /dev/ttyAMA1 device. This seems consistent with the description in the /boot/overlays/README file which states:
Name: Uart1
Info: Enable uart1 in place of uart0
I did find a limited driver for the mini-UART which is fixed at 115200 baud, which seems like a driver to use the mini-UART instead of the full UART.
What I'd like to do is: without redesigning the hardware, configure the "PL011" full UART to use the CTS/RTS/TX/RX port, and the mini-UART to use the TX/RX port, so that I can use both serial ports in my application.
