Serial API Reference

MIA accepts JSON commands over USB serial at 115,200 baud. Each command is a single line of JSON terminated with a newline (\n).

The easiest way to interact with the serial API is the included CLI tool:

python3 tools/mia-cli.py /dev/ttyUSB0

Or raw serial (useful for scripting):

python3 -c "
import serial, time
s = serial.Serial('/dev/ttyUSB0', 115200, timeout=2)
time.sleep(5)          # wait for boot
s.reset_input_buffer()
s.write(b'{\"cmd\":\"get_config\"}\n')
time.sleep(0.5)
print(s.read(s.in_waiting or 1).decode())
"

Note: Wait a few seconds after opening the port for the device to finish booting before sending commands. Sending too early can mix your command with boot output and cause a parse error.

Radio configuration

get_config

Returns current radio parameters.

Request:

{"cmd": "get_config"}

Response:

{
  "frequency": 906.875,
  "bandwidth": 250,
  "spreadFactor": 11,
  "codingRate": 5,
  "power": 22
}

set_config

Updates one or more radio parameters. Only include the fields you want to change. Changes take effect immediately and persist across reboots.

• frequency: frequency in MHz (e.g. 906.875)
• bandwidth: bandwidth in kHz (e.g. 250.0)
• codingRate: coding rate (5–8) Example: Request:

{"cmd": "set_config", "spreadFactor": 9, "power": 17}

Response:

{"status": "ok"}

Valid ranges:

• spreadFactor: 7–12 (RadioLib validates this; invalid values return {"status":"error"})
• power: −9 to 22 dBm

PSK (channel key)

get_psk

Returns the current AES channel key as base64.

Request:

{"cmd": "get_psk"}

Response:

{"psk": "1PG7OiApB1nwvP+rz05pAQ=="}

The response includes the raw base64 key. Decode it to get the actual bytes: 24 characters = 16 bytes (AES-128), 44 characters = 32 bytes (AES-256).

set_psk

Sets a new AES channel key. Must be a valid base64 string that decodes to exactly 16 bytes (AES-128) or 32 bytes (AES-256).

Request:

{"cmd": "set_psk", "psk": "uUAKMhSSaaZpRNM0ytp6qw=="}

Response:

{"status": "ok"}

To match a Meshtastic private channel, find the PSK in the Meshtastic app's channel settings (shown as base64) and pass it directly here.

WiFi / AP settings

get_wifi

Returns current WiFi AP configuration. The password is intentionally omitted from the response.

Request:

{"cmd": "get_wifi"}

Response:

{"enabled": true, "ssid": "Mesh Injection Apparatus"}

set_wifi

Updates WiFi AP settings. Any combination of fields can be included. SSID and password changes require a reboot to take effect; the enabled toggle applies on the next boot.

Request:

{"cmd": "set_wifi", "ssid": "MyMIA", "password": "newpassword", "enabled": true}

Response:

{"status": "ok"}

Defaults

save_defaults

Saves the current configuration (radio, PSK, WiFi) as a named restore point. A subsequent reset_defaults will return to these values rather than the compiled-in factory values.

Request:

{"cmd": "save_defaults"}

Response:

{"status": "ok", "msg": "current config saved as defaults"}

reset_defaults

Restores previously saved defaults. If no defaults have been saved, wipes NVS entirely and reverts to compiled-in factory values on next reboot.

Request:

{"cmd": "reset_defaults"}

Response:

{"status": "ok", "msg": "defaults restored, reboot to apply"}

or, if no saved defaults exist:

{"status": "ok", "msg": "factory reset, reboot to apply"}

Error responses

All commands return a consistent error format for invalid input:

Serial CLI quick reference

mia> get config              read radio parameters
mia> get psk                 read current PSK
mia> get wifi                read AP settings
mia> get status              read everything at once

mia> set sf <7-12>           set spread factor
mia> set power <dBm>         set TX power
mia> set psk <base64>        set channel key
mia> set ssid <name>         set AP network name
mia> set password <pass>     set AP password
mia> set wifi <on|off>       enable or disable the AP

mia> set freq <MHz>          set frequency
mia> set bw <kHz>            set bandwidth  
mia> set cr <5-8>            set coding rate

mia> gen psk 128             generate and apply a random 128-bit key
mia> gen psk 256             generate and apply a random 256-bit key

mia> defaults save           save current config as restore point
mia> defaults reset          restore saved defaults (or factory reset)

mia> monitor                 stream live serial output
mia> exit                    disconnect