INAV programming logic conditions

A condition has an operation, one or two operands, an enabled switch, and a Runs choice. Runs can be Always, or only while another condition is true. That second choice is how you chain them: one condition becomes the activator for the next. A condition cannot use itself as the activator.

The operation list is grouped. Logic covers always true, AND, OR, XOR, NAND, NOR, NOT, sticky, edge, delay and timer. Compare covers equal, greater, less, about equal, changed by, and low, mid or high on a channel. Maths covers add, subtract, multiply, divide, modulo, lower of, higher of, sine, cosine, tangent, and the two maps between 0 and 1000.

Variables cover set, increase and decrease of a global variable. Overrides cover arming, throttle, sticks, axis angle and rate, heading, loiter radius, minimum ground speed and ignoring a GPS fix. Outputs cover the control profile, the OSD layout, VTX power, band and channel, an IO port, LED pin PWM, gimbal sensitivity and starting compass calibration.

INAV 7 does not offer every row. The tab keeps operations whose id is below 53 on INAV 7, and shows the full list on INAV 8. If a condition you saved on a newer board is opened on an older one, expect the later operations to be missing rather than silently doing the new thing.

A number operand is a typed value from -1000000 to 1000000. Use it for a threshold, a delay in milliseconds, or a throttle pulse. An RC channel operand is channel 1 to 34. Low means the channel is below 1333 microseconds. High means it is above 1666 microseconds. Mid is the band between those two.

Flight data is the list the firmware reports: armed time, distances, RSSI, voltages in centivolts, current in centiamps, used capacity, satellites, speeds, altitude, throttle percent, attitude, and flags such as armed, returning home, landing and failsafe. INAV 8 adds the values after flight operand 41, including height above ground, mixer profile, wind and the later link figures. INAV 7 stops at 42 flight values, numbered from 0.

Flight mode is a named mode, including manual, return to home, position hold, cruise, altitude hold, angle, horizon, air mode and waypoint mission. Return to home in that list is the INAV mode. It is not Betaflight GPS Rescue. A logic-condition operand points at one of the other 64 slots. A global-variable operand is V1 to V8. A programming-PID operand is PID 1 to 4. Mission operands report whether a mission is flying, the current and next waypoint, and distances.

About equal is true when A is within 1 percent of B. Changed by is true when A changes by at least B within 100 ms. Edge is true for B milliseconds when A turns true. Delay becomes true only after A has stayed true for B milliseconds. Timer alternates on for A milliseconds and off for B milliseconds. Divide returns 0 when B is 0, so a condition does not fault on a zero divisor.

The eight global variables sit in their own card, labelled V1 to V8, with the live number from the board. The footer says they are shared numbers conditions can set and read, and that they reset to 0 at power-up. A set-variable operation writes B into variable A. Increase and decrease add or subtract B. Nothing on the card types a starting value that survives power-off. If you need a count of flaps or a timer tick, it starts again at 0 every time the board boots.

Four programming PIDs are separate from the flight PIDs on a Betaflight or INAV PID tab. Each one can be enabled, given a setpoint and a measurement, and given gains. Every gain is limited to -32767 through 32767. Clear turns that PID off. The setpoint and the measurement are operands, so a PID can chase a flight value, a variable or a number.

Use a programming PID when a condition needs a smooth approach to a target, such as a camera tilt or a flap that follows airspeed. Use a plain compare when you only need on or off. The live condition result and the live variable values are the check that the chain is doing what you think, before you fly it.

An override operation changes what the craft does while the condition is true. Set throttle forces a pulse in microseconds. Scale throttle scales it to a percent. Set RC channel forces channel A to B microseconds. Invert roll, pitch or yaw reverses that stick. Swap roll and yaw exchanges those two sticks. Set axis angle holds roll, pitch or yaw, numbered 0, 1 and 2, at B degrees. Set axis rate rotates that axis at B degrees per second.

Set heading sets a heading target in navigation modes. Set loiter radius takes centimetres. Set minimum ground speed takes metres per second. Ignore GPS fix treats the GPS as having no fix while the condition is true. Allow arming anyway skips the arming safety checks. That last one is a bypass. Use it only when you understand which check you are skipping, on the ground, with the props off.

Output operations do not fly the craft. They switch the control profile, show an OSD layout, set VTX power, band or channel, drive an IO port on or off, set LED pin PWM duty from 0 to 100, set gimbal sensitivity, or start compass calibration. Compass calibration from a condition is a start command. The alignment and the sweep itself are the compass screen.

The JavaScript card opens an editor. The button says examples, load from the flight controller, compile and apply. It is another way to write the same programming, not a second flight controller. If you use it, read the result back on the logic-conditions card so you can see which slots the script filled.

Add one condition, enable it, and pick an operation you can see. A high check on a spare channel is the usual first test: flip the switch and watch the live result change. Then point a second condition at the first with Runs set to while that condition is true. Save, and confirm the live flags still match the switch.

Do not test Set throttle, Allow arming anyway, or an axis override in the air on the first try. Those change the craft. Props off, on the bench, with a battery only if the motors must be powered, and with someone who can pull the battery. A compare or a global-variable write is the safe experiment.

Chrome or Edge on a computer connects over USB or Bluetooth. The Android app adds Wi-Fi. iPhone uses Bluetooth or Wi-Fi and has no USB host. The modes page is where flight modes get their switches. Programming can read those modes. It does not replace the mode ranges. Navigation numbers stay on the navigation page.