Connect to Edge 2

The serial console provides boot messages during startup and a shell without requiring a network connection. SSH provides a remote shell after the board has booted and is reachable over the network.

Serial console

A serial console gives you Edge 2's boot messages and a shell that does not depend on the network, which makes it the tool of choice when the board does not come up as expected.

You need a USB to TTL converter and a computer running Windows, macOS or Linux.

Wire the converter

Edge 2 has a three-pin debug UART header near the corner next to the POWER USB-C port. See Debug UART for the header location and pinout.

Connect only GND, TXD, and RXD. Transmit connects to receive in each direction:

Converter	Edge 2 debug header
GND	GND, pin 3
TXD	RXD, pin 1
RXD	TXD, pin 2

Figure 1. Converter wiring. TXD goes to RXD and RXD goes to TXD.

Serial settings

The debug UART runs at 1500000 baud, 8N1, with no flow control.

warning

Some USB to TTL converter chips cannot reach 1500000 baud. Check the converter's maximum baud rate before buying one.

Connect from your computer

Follow the instructions for your computer.

Windows

1. Install the driver for your USB to TTL converter. The driver comes from the converter's vendor, not from Mixtile.

2. Install PuTTY from its official download page. Choose the installer that matches your computer.

3. Plug the converter into the computer. Open Device Manager and read its COM port under Ports (COM & LPT), for example COM4.

   

4. Open PuTTY. Set Connection type to Serial, Serial line to the COM port you found, and Speed to 1500000.

   

5. Click Open.

To close the console, close the PuTTY window.

macOS

1. Install Homebrew if you do not have it, then install picocom:

   Host PC (macOS)

   brew install picocom

2. Plug the converter into the computer, then list the serial devices. The newly appearing device is the serial port, for example /dev/tty.usbserial-0001.

   Host PC (macOS)

   ls /dev/tty.*

3. Open the console, replacing the port with the one you found:

   Host PC (macOS)

   picocom -b 1500000 /dev/tty.usbserial-0001

To close picocom, press Ctrl+A, then Ctrl+X.

Linux

1. Install picocom:

   Host PC (Linux)

   sudo apt update
   sudo apt install picocom

2. Plug the converter into the computer, then list the serial devices. The port is usually /dev/ttyUSB0.

   Host PC (Linux)

   ls /dev/ttyUSB* /dev/ttyACM*

3. Open the console, replacing the port with the one you found:

   Host PC (Linux)

   picocom -b 1500000 /dev/ttyUSB0

   If your user cannot access the serial device, add the user to the dialout group, then log out and back in.

To close picocom, press Ctrl+A, then Ctrl+X.

Log in on the console

The console may be blank until the board outputs something. If nothing appears, press Enter.

When the login prompt appears, sign in with the credentials for the operating system running on the board. For Mixtile OS, see Login details.

Serial troubleshooting

Symptom	What to check
Nothing appears after connecting	Press Enter. If there is still nothing, check the wiring and the baud rate.
Characters are garbled	The baud rate is wrong, or the converter cannot sustain 1500000 baud.
The port does not appear	The converter driver is not installed, or the converter is plugged into a port that does not enumerate. Try another cable and another USB port.
Output appears but typing does nothing	Flow control is on: turn it off in the terminal program. If it is already off, TXD and RXD are the wrong way round. The converter's TXD goes to the board's RXD.

SSH

SSH gives you a shell over the network. The board must be booted and reachable from your computer. Mixtile OS runs an SSH server in both the server and the desktop edition, and gets its Ethernet address by DHCP.

Find the board's IP address

Pick whichever is available to you:

• Router: look for mixtile-edge2 in the DHCP client list of your router's admin page.
• On the board: run ip addr on the monitor or the serial console.
• Scan the subnet: nmap -sn 192.168.1.0/24, adjusted to your subnet.

Log in

Replace <user> with a user of the system running on the board. For Mixtile OS, see Login details.

Host PC

ssh <user>@<board-ip>

The first connection asks you to confirm the host key. Answer yes once and it is remembered.

SSH troubleshooting

Symptom	What to check
Connection refused	The board has not finished booting, or no SSH server is running. Check over the serial console.
No route to host	The board is on a different subnet, or it never got an address. Check the Ethernet link LED and the router's client list.
Permission denied	Wrong user name or password for the system on the board.
REMOTE HOST IDENTIFICATION HAS CHANGED	The board was reflashed and generated a new host key. Remove the old entry with ssh-keygen -R <board-ip>.