This is alternative firmware for the MikroKopter NaviCtrl board developed by Chris Raabe at the University of Tokyo.

Not yet plug and play

USE AT YOUR OWN RISK

• NaviCtrl V2.0 or V2.1
• LSM303D magnetometer (IC5 should be unpopulated)

This firmware requires the following modifications to the NaviCtrl board

• A pull-up resistor (4.7K) must be added to pin 5 of the FlightCtrl header
• A pull-down resistor (4.7K) must be added to pin 8 of the Extension III header
• An optional button attached between pins 4 and 8 of the Extension III header

This firmware is intended to wholly replace the MikroKopter ecosystem. It may or may not be compatible with the MikroKopter tool in the future, but is not as of now.

The primary goal of the firmware is to provide unrestricted navigation and to interface with a custom (vision) position sensor.

This software was developed for use with the arm-none-eabi gcc toolchain.

Hex files can be uploaded using the Mikrokopter Tool or the firmware uploader (Linux) available at https://github.com/ctraabe/MKProgrammer

This program is based on a combination of interrupts and polling.

Interrupt priority:

1. Millisecond timer (1 kHz)
2. Flight Ctrl SPI interrupt (<40 kHz)
3. SD card SPI interrupt (<32 kHz)
4. I2C to magnetometer and EEPROM (<40 kHz)
5. UBlox UART interrupt (<1 kHz)
6. "Debug" UART interrupt (<1 kHz)
7. Low-priority data processing interrupt (< 300 times per second)
8. Interrupt from FlightCtrl (128 Hz)
9. 50 Hz software interrupt (50 Hz)
10. SD card inserted/ejected (rare)

Main loop:

(out of date)

1. Receive interrupt from FlightCtrl indicating a new 128Hz frame
2. Request the latest magnetometer reading from LSM303D
3. Process any data received from UBlox GPS
4. Compute position delta, velocity, and heading correction (Kalman filter)
5. Notify FlightCtrl of update via the interrupt line
6. Exchange data with FlightCtrl (SPI)
7. Log data to SD card