Setup Serial Debugging Tool

Preparation

Connections

Follow these steps to make the correct connections:

  • Connect the Tool Pins to the GPIOs, and check the Tx / Rx Pins once more to ensure that you’ve made correct connections:

    • Tool Pin GND: <—> Pin17 of VIM’s GPIO
    • Tool Pin TXD: <—> Pin18 of VIM’s GPIO (Linux_Rx)
    • Tool Pin RXD: <—> Pin19 of VIM’s GPIO (Linux_Tx)
    • Tool Pin VCC: <—> Pin20 of VIM’s GPIO

  • Insert the USB-end into your PC.

The connections should look like this:

Image of SerialConnections

  • Blue color line: Tool Pin TXD
  • Orange color line: Tool Pin RXD
  • Black color line: Tool Pin GND

Another photo for more details (VCC Pin is not necessary):

Image of SerialConnections

Setup Serial Communication Program

On Ubuntu system, you can use minicom serial communication program.

  • Install minicom
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$ sudo apt update
$ sudo apt install minicom
  • Add access permission
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$ sudo usermod -a -G dialout $(whoami)

You may need to logout or reboot your system.

  • Setup minicom

Before setup minicom, you need to connect the USB to TTL Converter tool to your device and computer.

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$ sudo minicom -s

You will enter minicom setup mode, like this:

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+-----[configuration]------+
| Filenames and paths      |
| File transfer protocols  |
| Serial port setup        |
| Modem and dialing        |
| Screen and keyboard      |
| Save setup as dfl        |
| Save setup as..          |
| Exit                     |
| Exit from Minicom        |
+--------------------------+

You can use up/down arrow on the keyboard to shift to Serial port setup item and hit Enter to Serial port setup menu.

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+-----------------------------------------------------------------------+
| A -    Serial Device      : /dev/ttyUSB0                              |
| B - Lockfile Location     : /var/lock                                 |
| C -   Callin Program      :                                           |
| D -  Callout Program      :                                           |
| E -    Bps/Par/Bits       : 115200 8N1                                |
| F - Hardware Flow Control : No                                        |
| G - Software Flow Control : No                                        |
|                                                                       |
|    Change which setting?                                              |
+-----------------------------------------------------------------------+
        | Screen and keyboard      |
        | Save setup as dfl        |
        | Save setup as..          |
        | Exit                     |
        | Exit from Minicom        |
        +--------------------------+

You can use Shift + A to setup the serial device, and hit Enter to confirm.
You can use Shift + E to setup the baudrate, choose 115200 and hit Enter to confirm.
You can use Shift + F to disable the hardware flow control, set to NO.
When you done all the setup, you can hit Enter to exit the menu, and then choose Save setup as dfl to save the configuration, then Exit from Minicom.

Note

You need to replace the serial device node to the correct one on your computer.

  • Launch minicom

Type minicom command in terminal will enter the board serial terminal.

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$ minicom
elcome to minicom 2.7.1

OPTIONS: I18n 
Compiled on Dec 23 2019, 02:06:26.
Port /dev/ttyUSB0, 15:24:13

Press CTRL-A Z for help on special keys

Ubuntu 20.04.2 LTS Khadas ttyS0

Khadas login: 
Khadas login: 
Khadas login:
  • Exit minicom

You can use Ctrl + A + Z to lanuch the menu:

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+-------------------------------------------------------------------+
|                      Minicom Command Summary                      |
|                                                                   |
|              Commands can be called by CTRL-A <key>               |
|                                                                   |
|               Main Functions                  Other Functions     |
|                                                                   |
| Dialing directory..D  run script (Go)....G | Clear Screen.......C |
| Send files.........S  Receive files......R | cOnfigure Minicom..O |
| comm Parameters....P  Add linefeed.......A | Suspend minicom....J |
| Capture on/off.....L  Hangup.............H | eXit and reset.....X |
| send break.........F  initialize Modem...M | Quit with no reset.Q |
| Terminal settings..T  run Kermit.........K | Cursor key mode....I |
| lineWrap on/off....W  local Echo on/off..E | Help screen........Z |
| Paste file.........Y  Timestamp toggle...N | scroll Back........B |
| Add Carriage Ret...U                                              |
|                                                                   |
|             Select function or press Enter for none.              |
+-------------------------------------------------------------------+

And use Shift + Q to exit minicom.

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+----------------------+
| Leave without reset? |
|     Yes       No     |
+----------------------+

Choose Yes and hit Enter to exit minicom.

Tips

  1. If the terminal output contains this line, you might need to type sudo minicom.

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    /dev/ttyUSB0: Permission denied

  2. To access U-boot, leave your USB-Serial-Debug tool connected, then press the reset button on your device once. You should see some print-out on your terminal, then quickly press the space-bar or control-c to stop auto-boot. You will see the prompt kvim# when you’ve entered u-boot.

  3. Note that to see the standard “help” commands as listed in the U-Boot Usage Guide, you’ll need to first have a version of Android or Ubuntu installed in your VIM device, from our krescue images.

  4. You can use the U-Boot command line (kvim#), to change your VIM’s default boot logo.bmp, according to the guide, Boot Logo for U-Boot.

See Also

On Windows system, you can use SecureCRT serial communication program.

  • Install USB to TTL Converter Driver

If you haven’t install USB to TTL Converter driver, you need to install it. Here we take CH340 as a example.

  1. Download the driver here
  2. Unzip the file
  3. Run the installer which you unzipped
  • Install SecureCRT

Please access SecureCRT official website to down and install it.

  • Setup SecureCRT

Before setup SecureCRT, you need to connect the USB to TTL Converter tool to your device and computer.

Launch SecureCRT and navigate to File->Quick Connect:

securecrt1

Select protol Serial, and select correct device node, baudrate set to 115200, unselect XON/XOFF.

securecrt2

Then click Connect will enter the board serial terminal.

securecrt3

On Mac OS system, you can use minicom serial communication program.

  • Setup the terminal

As minicom need Meta key, so you need to setup your terminal Meta option.
Go to Terminal->Preferences->Keyboard, select Use Option as Meta key.

minicom1

minicom2

minicom3

  • Install minicom

You may need to install homebrew if you haven’t instll it.

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$ brew install minicom
  • Setup minicom

Before setup minicom, you need to connect the USB to TTL Converter tool to your device and computer.

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$ minicom -s

You will enter minicom setup mode, like this:

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┌─────[configuration]──────┐
│ Filenames and paths      │
│ File transfer protocols  │
│ Serial port setup        │
│ Modem and dialing        │
│ Screen and keyboard      │
│ Save setup as dfl        │
│ Save setup as..          │
│ Exit                     │
│ Exit from Minicom        │
└──────────────────────────┘

You can use up/down arrow on the keyboard to shift to Serial port setup item and hit Enter to Serial port setup menu.

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┌───────────────────────────────────────────────────────────────────────┐
│ A -    Serial Device      : /dev/tty.usbserial-1410                   │
│ B - Lockfile Location     : /usr/local/Cellar/minicom/2.7.1/var       │
│ C -   Callin Program      :                                           │
│ D -  Callout Program      :                                           │
│ E -    Bps/Par/Bits       : 115200 8N1                                │
│ F - Hardware Flow Control : No                                        │
│ G - Software Flow Control : No                                        │
│                                                                       │
│    Change which setting?                                              │
└───────────────────────────────────────────────────────────────────────┘
        │ Screen and keyboard      │
        │ Save setup as dfl        │
        │ Save setup as..          │
        │ Exit                     │
        │ Exit from Minicom        │
        └──────────────────────────┘

You can use Shift + A to setup the serial device, and hit Enter to confirm.
You can use Shift + E to setup the baudrate, choose 115200 and hit Enter to confirm.
You can use Shift + F to disable the hardware flow control, set to NO.
When you done all the setup, you can hit Enter to exit the menu, and then choose Save setup as dfl to save the configuration, then Exit from Minicom.

Note

You need to replace the serial device node to the correct one on your computer.

  • Launch minicom

Type minicom command in terminal will enter the board serial terminal.

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$ minicom
Welcome to minicom 2.7.1

OPTIONS: 
Compiled on Sep 18 2017, 15:01:35.
Port /dev/tty.usbserial-1410, 16:02:04

Press Meta-Z for help on special keys

Ubuntu 20.04.2 LTS Khadas ttyS0

Khadas login: 
Khadas login: 
Khadas login:
  • Exit minicom

You can use option + Z to lanuch the menu:

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┌───────────────────────────────────────────────────────────────────┐
│                      Minicom Command Summary                      │
│                                                                   │
│               Commands can be called by Meta-<key>                │
│                                                                   │
│               Main Functions                  Other Functions     │
│                                                                   │
│ Dialing directory..D  run script (Go)....G | Clear Screen.......C │
│ Send files.........S  Receive files......R | cOnfigure Minicom..O │
│ comm Parameters....P  Add linefeed.......A | Suspend minicom....J │
│ Capture on/off.....L  Hangup.............H | eXit and reset.....X │
│ send break.........F  initialize Modem...M | Quit with no reset.Q │
│ Terminal settings..T  run Kermit.........K | Cursor key mode....I │
│ lineWrap on/off....W  local Echo on/off..E | Help screen........Z │
│ Paste file.........Y  Timestamp toggle...N | scroll Back........B │
│ Add Carriage Ret...U                                              │
│                                                                   │
│             Select function or press Enter for none.              │
└───────────────────────────────────────────────────────────────────┘

And use Shift + Q to exit minicom.

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+----------------------+
| Leave without reset? |
|     Yes       No     |
+----------------------+

Choose Yes and hit Enter to exit minicom.

Next