Q1) I have connected the SWD but I get an error when trying I connect with the debugger. I am powering the FCU board with micro USB.
A1) You need always to connect also the battery to the STEVAL-FCU001V1, not only the microUSB cable. The USB will give power to the battery charger IC on board to charge 1S battery, it's not giving power directly to the STM32. Please refer to schematics of the board for details.
Q2) I cannot keep the drone still in hovering mode, it has tendency to fly in one specific direction.
A2) There may be several reasons to check:
- Sensor Calibration has not been perfomed after power up of the FCU. Please read the instructions and make sure you run the sensor calibration after start up and before Arming procedure. Make the calibration with the drone on a flat surface, and check if the corresponding LED is turned ON (please check documentation or FW source code for details)
- One motor is defective. It happens easily with cheap DC brushed motor that can be defective even if new, or can be damaged after a crash.
- In case external remocon is used, joystick offset (for ELE, AIL and RUD should be approximately zero when sticks in center position) has not been calibrated in the FCU FW source code. Please refer to documentation for details.
Q3) Sensor calibration offset data is saved if I unplug and plug again the battery?
A3) No, in current FW implementation the calibration offset data are not saved in Flash, and sensor the calibration procedure must be performed every time the FCU is powered on.
Q4) I have connected my FCU to my Android device using the BLE communication configuration, but when I spin the motors the BLE connection is lost.
A4) The issue may appear if the battery used is not big enough to sustain the inrush current of the motors when they start to spin, and the significant voltage drop on Vbus may cause issue or reset of the BLE module or the STM32.
Q5) Are the pressure sensor and the magnetometer used for flying the drone?
A5) No, in current FW revision the data of the pressure sensor and magnetometer are read and sent to BLE Android app for datalog, but they are not used to fly the drone. Only 6-axis accelerometer and gyroscope are used for drone stabilization and control. The pressure sensor can be used for altitude control, and the magnetometer (eventually in combination with an external GPS module) for auto navigation.
Q6) Can I use 2S or 3S battery connected directly to the FCU STEVAL-FCU001V1?
A6) No, only 1S battery can be connected directly. If you want to use 2S and 3S battery (with motors that can operate at higher voltage), you need to make few HW customization and use an external DCDC. Please refer to schematics and documentation for details.
Q7) Can I use the FCU with external ESC and DC brushless motors?
A7) Yes, but you need to make a small modification on the PCB board (few bridges/0ohm resistors to be changed) in order to use external ESC. Please refer to documentation for it. In case of ESC with integrated BEC or external PDB, you may power up STEVAL-FCU001V1 with external 5V.
Q8) Which is the maximum distance for BLE connection?
A8) The maximum distance supported may vary on the Android Smartphone/Tablet used or on the external environment (presence of walls, other 2.4GHz devices operating in same area, ...). By the way commonly 15 meters may be taken as reference value.
Q9) I have mounted my mini drone and make the first test flight, but the drone immediately flip over. Which may be the issue?
A9) Verify the motors are connected in the right order, please refer to documentation for it.
Q10) I have mounted my mini drone and make the first test flight, the motor spins but the drone is not taking off.
A10) There may be 2 issues:
- The motors are not rotating in the right direction or the propellers are not mounted in the correct way. Please refer to documentation.
- The battery voltage is too low. Please check if the battery is full charged (4.2V in case of 1S Lipo).
- The drone is too heavy for the propellers used and the thrust generated is not enough.
Q11) Which motors and propellers should I use?
A11) For the first test it's suggested to start with a DC brushed motor configuration to take confidence with the FCU and its FW project. The LV Mosfet present on the board have been selected and verified with the following configuration:
- 8520 coreless DC motor
- 65mm propeller
- max 70g overall drone weight (frame and battery included)
Q12) Can I used the USB to connect the FCU to the PC in order to log some data or other purpose?
A12) Yes, but actually the USB driver has not yet implemented in current FW project implementation. You can easily implement it or wait for next FW releases. Actually the micro USB connector is used only for battery charging purpose.
Q13) Can I see the log of data on my PC? What should I use?
A13) In the actual FW implementation the PRINTF in the source code are used for data log using the UART port (please refer to documentation for it). You need to use a UART to USB connector (for example an STM32 Nucleo board) to interface to the PC. Another possibility is to connect a Bluetooth module with SPP interface connected to the FCU UART.