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Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

Recipe

Find the port your board is on

Use when: you need to choose a port for an upload or a serial monitor and aren't sure which entry is your board

Goal: the one port name that belongs to your board, confirmed by unplugging it

Taught in Ports, drivers and permissions

Quick recipe

  1. List the ports with the board unplugged
  2. Plug the board in with a data cable and list again
  3. Check the name's pattern
  4. Open it
  1. 1

    Use Device Manager, ls /dev/cu.*, ls /dev/tty*, or arduino-cli board list.

    Why: whatever is listed now belongs to the computer, not to the board.

  2. 2

    The new entry is the board's port.

    • nothing new appears — try another cable, then another socket.
    • two new entries — you have plugged in two boards, or a DevKitC-1 by both ports; unplug one.

    Why: comparing the two lists removes every guess about names.

  3. 3

    ACM or usbmodem means native USB; USB or usbserial means a bridge chip.

    Why: a bridge port that never appears may need the chip maker's driver; a native port never does.

  4. 4

    Select it in the IDE or pass it to -p. On Linux, "Permission denied" means joining the dialout group, then logging out and back in.

    Why: finding a port and being allowed to open it are separate steps.

Common mistakes

  • Picking a Bluetooth or debug port because it was first in the list.
  • Installing a driver for a native-USB board, which never needs one.
  • Testing with a charge-only cable and blaming the board.