What happens when battery is nearly out in flight?

If Phenox2 is in flight when battery is nearly out, Phenox2 enters landing state ('PX_DOWN'), then stops all motors. So please type 'halt' command to shutdown Phenox2 manually, set power swith off and change battery.

(Tutorials insert function to shutdown automatically when battery is nealy out.)

But if Phenox2 is not in flight state, no message appers (todo). Please consider battery life when users operate Phenox2 with battery.

What happens when Linux is down in flight?

In all Phenox programs, CPU0 (Linux) sends keepalive message to CPU1 (flight control program) periodically by calling pxset_keepalive() (See detail in C Language API) If CPU1 detects keepalive message is not coming for a while, CPU1 operates Phenox2 as following rule.
- If Phenox2 is in hovering state (pxget_operatemode() == PX HOVER), keep hovering, then start landing when battery is nealy out. - No take off messages are received from CPU0.

Phenox2 falls suddenly during flight.

Please check battery cable. Isn't it nearly disconnected?

Booting Linux is not successful.

Booting Linux sometimes fail like following pattern.
- LED0, LED1 and LED2 continue to turn on, and no messages apper on serial communication board.
If this happens, eject and inject microSD, and set power switch on again and see LED0 and LED1 for 10~20 seconds (If booting Linux is successful, LED0 and LED1 are off after 2 seconds of on state, and LED2 is always on.).

Before changing propellers

Propellers has 2 type of rotating direction (CW and CCW). So please choose proper type of propellers when users change them. Propellers are attached to the shaft of motor without glue, so they can be removed by hand.

Changed payload but Phenox2 doesn't fly.

Users need to consider following two changes when payload is added.
1. Bias thrust of each rotors.
2. Total thrust of each rotors.

To change bias thrust of each rotors, edit parameter.c and change 4 variables (duty_bias_front,duty_bias_back,duty_bias_left,duty_bias_right). Those 4 variables represents additional thrust, and -250 to 250 is recommended value. For example, following setting increase thrust of left rotor, and decrease thrust of right rotor, which result in Phenox2 is likely to moving right.

param.duty_bias_front = 0;
param.duty_bias_back = 0;
param.duty_bias_left = 130;
param.duty_bias_right = -130;

To change total thrust of each rotors, edit parameter.c and change 5 variables (duty_hover,duty_hover_max,duty_hover_min,duty_hover_up,duty_hover_down). See Parameters for detail.

One thing users have to consider is the parameters duty_hover_down. It is constant thrust when Phenox2 is in landing state (PX_DOWN). So if this value is too large, Phenox2 moves "up" in "landing state", and stops all motors after the time('downtime_max') has elapsed, which results in fall down.

Anyway, please set parameters carefully and keep an eye on Phenox2 when parameters are changed.

No message appears on termial, or LEDs start blinking.

Battery may be almost out. Please check battery voltage, and recharge if needed.

My main board is dead?

Circuit boards don't talk a lot, but they never break doen without any reasons. Reasons why the main board breaks down are almost two patterns. The first is that other metal stuff is touched to the circuit board unfortunately to cause short circuit. The second is that the circuit board is bent by too large load.

The easiest way to judge whether the main board is alive is to check LED2. If it is lighting when the power switch is on, main board is alive. If 3 LEDs (LED0, LED1, LED2) are always on, please check that a microSD is inserted to the main board, or see Booting Linux is not successful. (above FAQ)