VIM3/3L Setup Serial Debug Console

Introduction

This page will introduce the serial tool. You will learn how to connect Khadas SBC to PC and install debugging software on different PCs.

Preparation

Take a serial tool, which is also known as an USB to TTL Converter like CH340 USB to TTL Converter.

Hardware Connection

You can connect your serial tool to the board GPIO pins, referring to the following diagram，

Serial tools pin	GPIO board header pin	Name
`GND`	`17`
`TXD`	`18`	`Linux_Rx`
`RXD`	`19`	`Linux_Tx`
`VCC(3.3V)`	`20`

Insert the USB port into your computer.

Blue line: TXD
Orange line: RXD
Black line: GND

Setup Serial Communication Program

VIM1/VIM2/VIM3/VIM3L Baudrate: 115200
VIM4/VIM1S Baudrate: 921600
Edge1/Edge2 Baudrate: 1500000

Ubuntu

Use the minicom serial communication program.

1. Install

$ sudo apt update
$ sudo apt install minicom

Add permissions to access

$ sudo usermod -a -G dialout $(whoami)

You may need to logout or reboot your system to take effect.

2. Setup

Connect your SBC to the computer via the USB to TTL Converter tool before setting up minicom.

$ sudo minicom -s

Enter the minicom setup mode:

+-----[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        |
+--------------------------+

Use the up/down arrow keys to shift to Serial port setup, and hit Enter to enter the Serial port setup menu.

You can use Shift + A to setup the serial device, 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.

After completing the setup, hit Enter to exit, then choose Save setup as dfl, then Exit from Minicom.

The serial device node must correspond to Ubuntu’s serial device node.

3. Launch

Type minicom into the Ubuntu Terminal:

$ 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:

4. Exit

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

+-------------------------------------------------------------------+
|                      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.              |
+-------------------------------------------------------------------+

Use Shift+Q to exit minicom.

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

Choose Yes and hit Enter to exit minicom.

If the Terminal output contains this line, you need to use sudo minicom.
```
/dev/ttyUSB0: Permission denied
```
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 or control-c to stop auto-boot. You will see the prompt kvim# when you've entered U-boot.
Standard “help” commands are listed in U-Boot Usage Guide, you’ll need to first have a version of Android or Ubuntu installed in your VIM device, from our official OOWOW images.

Windows

1. Install Driver

Install the CH340 driver.

Download the driver.
Unzip the compressed file.
Run the installer.

2. Install SecureCRT

Download the program from the SecureCRT website.

3. Setup SecureCRT

Before starting SecureCRT, you’ll need to connect the USB to TTL Converter tool to your SBC and computer.

Launch SecureCRT and navigate to File→Quick Connect:

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

Click Connect.

Mac OS

1. Setup Meta key

minicom needs a Meta key. Use Terminal to create a Meta key. Go to Terminal→Preferences→Keyboard, select Use Option as Meta key.

2. Install

$ sudo apt update
$ sudo apt install minicom

Add access permissions

$ sudo usermod -a -G dialout $(whoami)

You may need to logout or reboot your system for changes to take effect.

3. Setup

Connect the USB to TTL Converter tool to your SBC and computer before setting up minicom.

$ sudo minicom -s

Enter the minicom setup mode:

+-----[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        |
+--------------------------+

Use the up/down arrows to shift to Serial port setup, and hit Enter to enter the Serial port setup menu.

You can use Shift + A to setup the serial device, 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.