Exp Header UART for TTL is True Serial Console (very nice)

[peterz]

hi Peterz,

Those RS232 modules are very interesting; actual 9pin shells !  (takes me back a few years)

The six uart(s) are as follows (of which you found five... ):

uart0:   EXP pins pb8 & pb9    duplicated on euler bus pin(29) & pin(30)
uart1:   wifi|bt  pins  pg6 & pg7
uart2:   pi bus  pins pb0 & pb1
uart3:   euler bus pd0 & pd1
uart4:   euler bus pd2 & pd3
S-uart   wifi|bt  pl2 & pl3

If you use the serial console, bluetooth, and wifi, then only three uart(s) are available to you for serial comm... uart2-4.

I use the wifi and bt module, so S-uart and uart1 are out...  i usually use the serial console too... so that leaves me uart3 & uart4 on the euler bus, and uart2 on the pi bus.

marcushh777

Hi marcushh777 ,

yes, I do not plan to use wifi/BT module.
I disabled uart0 as well (to have more uarts available).
Any idea how to enable S-uart? Somewhere on this forum someone made BT working. So this UART should be usable somehow.

Now I experimented with ch341 and FTDI USB to RS232 converters through powered USB HUB.
Comparing those small modules with USB to RS232 adapters. Adapters are ugly.

CH341 are cheap but doesn't work with all devices.
FTDI works with all devices but costs several times more than ch341.

Code:

debian@pine64:~$ dmesg |grep tty
[    0.000000] Kernel command line: console=tty0 no_console_suspend disp.screen0_output_mode=720p60 earlycon=uart,mmio32,0x01c28000 mac_addr=36:c9:e3:f1:b8:05 root=/dev/mmcblk0p2 ro rootwait
[    0.000000] console [tty0] enabled
[    6.850014] uart0: ttyS0 at MMIO 0x1c28000 (irq = 32) is a SUNXI
[    6.850575] uart1: ttyS1 at MMIO 0x1c28400 (irq = 33) is a SUNXI
[    6.850943] uart2: ttyS2 at MMIO 0x1c28800 (irq = 34) is a SUNXI
[    6.851410] uart3: ttyS3 at MMIO 0x1c28c00 (irq = 35) is a SUNXI
[    6.851843] uart4: ttyS4 at MMIO 0x1c29000 (irq = 36) is a SUNXI
[    9.041264] systemd[1]: Starting system-getty.slice.
[    9.064663] systemd[1]: Created slice system-getty.slice.
[   12.343653] usb 3-1.1: ch341-uart converter now attached to ttyUSB0
[   12.572968] usb 3-1.2: ch341-uart converter now attached to ttyUSB1
[   13.242064] usb 3-1.3.1: ch341-uart converter now attached to ttyUSB2
[   13.478980] usb 3-1.3.2: ch341-uart converter now attached to ttyUSB3
[   13.714362] usb 3-1.3.3: ch341-uart converter now attached to ttyUSB4
[   13.942676] usb 3-1.3.4: ch341-uart converter now attached to ttyUSB5
[   14.166052] usb 3-1.4.1: ch341-uart converter now attached to ttyUSB6
[   14.395654] usb 3-1.4.2: FTDI USB Serial Device converter now attached to ttyUSB7

Here is the picture. If I will combine both options I will have to play with UDEV rules (did that in the past, just have to find config).


BR,
Peter