Safety and limits
Safety is a design rule, not a feature. Everything here is enforced by the firmware on the device itself, whatever an app asks for.
Temperature limits
Section titled “Temperature limits”| Device | Flower | Concentrate | Hard ceiling |
|---|---|---|---|
| Carta 2 | 275–500 °F | 365–635 °F | 635 °F |
| Aeris | 275–500 °F | 365–600 °F | 635 °F |
| Carta Sport | 275–500 °F | 365–635 °F | 635 °F |
Curve stages are clamped to the same limits. A curve’s ramp is slowed so the setpoint never rises faster than 1.1 °C per second, and a curve runs for 15 minutes at most.
The heater
Section titled “The heater”- The heater is off the moment the device boots.
- The heater only runs while the main program has renewed it in the last 100 ms. If the program stalls, the heater turns off within that window.
- A 1-second watchdog resets the device if the main program stops.
- Updating stops any session and holds the heater off, and every write to the device’s memory forces the heater off first.
Faults
Section titled “Faults”A fault stops the heater immediately. It is shown on screen (Carta 2), as red and amber blinks, and as a long “refused” pulse. The codes match the factory screens where one exists.
| Code | Name | What triggers it |
|---|---|---|
| 502 | Heating failed | The chamber is still at or below 54 °C after 7.5 s, or has not reached its target within 65 s |
| 504 | Short circuit | The coil’s electrical readings are outside what a healthy coil gives |
| 505 | No atomizer | There is no atomizer at the start, or it was removed during a session |
| 510 | Sensor fault | The temperature sensor reads an impossible value, or gave no fresh reading for 2 s while heating |
| 511 | Too hot | The temperature went above the hard ceiling |
| 512 | Heater fault | More than 40 °C above the setpoint and not cooling for 3 s, or above it for 2 minutes whatever the trend. Lowering the temperature mid-session is not a fault. |
| 520 | Low battery | A session was refused because of the battery, or stopped at critical battery |
| 530 | Time limit | A session ran longer than the max session length plus 2 minutes (30 minutes at most) |
Battery
Section titled “Battery”- A warning is shown below 20 %.
- The Carta 2 refuses to start a session below 19 %.
- At critical battery (3 % or less, or about 6 V on the two-cell Carta Sport) for twenty checks in a row, the session stops and the device powers off. This only applies while it is on. On the charger it keeps charging.
Safe mode
Section titled “Safe mode”If the device fails to run normally for four boots in a row, it starts in safe mode. In safe mode:
- the heater is never enabled,
- only Bluetooth and updating work,
- it advertises as Dialed SAFE,
- on a Carta 2 the screen shows an amber SAFE MODE notice (“The heater is off”, “Update over Bluetooth”). On the one-button devices the lights and buzzer stay quiet. If a Carta 2’s screen stays completely black in safe mode, the display itself is not working.
Safe mode is how a bad update or a fault can never leave you with a hot, uncontrolled device. After 15 seconds the next boot tries normal operation again. After 10 minutes without a connection the device sleeps until a button press or USB connection. Turning the device off on purpose, or rebooting it, never counts towards safe mode.
Memory
Section titled “Memory”Settings are stored in two copies with a checksum, written so that a power cut during a save always leaves the previous copy valid. The factory identity, Bluetooth address and calibration areas are read-only to Dialed Control.