HOW TO - Connect the serial console

[Yoast]

This explains how to connect a serial console to the ROCKPro64. In this example I'm using the console sold by the Pine64 folks, but probably works for other serial consoles as well.

Parts/software needed
1) ROCKPro64 (I'm using the Rockpro64_V2.1 2018-06-06, 2GB version)
2) Serial console (I'm using a CH340G chipset based console, the one from Pine64)
3) Three F/F jumper wires (4 are included in the serial console from Pine64 and are 15 cm long)
4) Screen, Minicom or Picocom installed on a Linux distro

Steps

Connect the serial console to the PI-2-bus on the ROCKPro64

1. Set the yellow jumper on the serial console to 3V3 (see the picture below)
   
2. Connect a F/F jumper cable to the ground (GND) on the serial console and the other end to pin#6 of the PI-2-bus (black cable in the picture)
   
3. Connect a F/F jumper cable to RTX on the serial console and the other end to pin#8 of the PI-2-bus (brown cable in the picture)
   
4. Connect a F/F jumper cable to TXD on the serial console and DO NOT connect it to the ROCKPro64 (I'll explain below)
   

The reason for not connecting that last jumper cable to the ROCKPro64 is that in my case the ROCKPro64 doesn't boot when it is connected. When the cable is disconnected it boots fine. It is not really a problem because this connection is for sending. Receiving works just fine (and that is usually the reason why people use the serial console in the first place). Nevertheless, once the system is booting (or finished booting) you can connect the jumper cable and send commands to the ROCKPro64.


Connect the serial console to another computer and establish a connection
[1] Plug in the console into an USB port. I'm using a MacbookPro running Arch Linux:

Code:

[root@mbp_arch ~]# uname -a
Linux mbp_arch 4.17.13-arch1-1-ARCH #1 SMP PREEMPT Mon Aug 6 23:06:31 UTC 2018 x86_64 GNU/Linux

[2] Figure out how to access the serial console:

Code:

[root@mbp_arch ~]# dmesg | tail
[   70.843501] usb 3-1: new full-speed USB device number 2 using ohci-pci
[   71.071013] usb 3-1: New USB device found, idVendor=1a86, idProduct=7523, bcdDevice= 2.62
[   71.071023] usb 3-1: New USB device strings: Mfr=0, Product=2, SerialNumber=0
[   71.071028] usb 3-1: Product: USB2.0-Serial
[   71.103892] usbcore: registered new interface driver usbserial_generic
[   71.103903] usbserial: USB Serial support registered for generic
[   71.105335] usbcore: registered new interface driver ch341
[   71.105348] usbserial: USB Serial support registered for ch341-uart
[   71.105374] ch341 3-1:1.0: ch341-uart converter detected
[   71.119050] usb 3-1: ch341-uart converter now attached to ttyUSB0

[3] The way to access the console is through ttyUSB0 (in my case, it could be different for you)
[4] Open a terminal and start screen, minicom or picocom with the following parameters:

Code:

[root@mbp_arch ~]# screen /dev/ttyUSB0 1500000

Code:

[root@mbp_arch ~]# picocom /dev/ttyUSB0 -b 1500000

Code:

[root@mbp_arch ~]# minicom -D /dev/ttyUSB0 -b 1500000

This will start the application with a baud rate of 1.5M on ttyUSB0 (which we have just established is the serial console)

[5] Connect the power cable to the ROCKPro64 and enjoy the boot messages that will show. At this point you can connect the last jumper cable to pin#10 on the PI-2-bus which will allow you to send as well (and be able to login).
[6] To quit screen press 'ctrl-a' first followed by 'k'. Answer 'y' to the question to kill the current connection. To quit minicom press 'ctrl-a' followed by 'x' and select 'yes'. For picocom press 'ctrl-a' first and then 'ctrl-q'.


Hope this guide is clear. Suggestions are welcome