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Flight control system firmware for the SFWA CPU board DSP (TMS320C6657)


Requires cmake version 2.8.7 or higher.

Create a build directory outside the source tree, then use cmake to generate the makefile.

Note: currently only tests can be built

mkdir fcs_build

cd fcs_build

cmake /path/to/fcs/test

Now, build the library using the make command.


The googletest library is used for unit testing.

After creating the build directory, make check will automatically download and build googletest, build the unit tests and then run them.

To build the unit tests without running them, use make unittest. The unit tests can be run manually (with more detailed reporting) by executing ./unittest in the build directory.

Copying firmware to SPI flash

After building the fcs project, CCS will generate an fcs.btbl file which is used as the basis for the firmware image.

Run cd fcs/ccs-scripts && make fcs.debug.bin (or fcs.release.bin) to build the necessary firmware image conversion tools and output the firmeware image to fcs.debug.bin in the fcs/ccs-scripts directory.

Move that file to c6657-norwriter/bin/app.bin, then follow "Steps to program the NOR" in c6657-norwriter/docs/README.txt.


Main bootloader executes AHRS on core 0, and NMPC on core 1.

AHRS task (boots first, only executes on core 0):

  • SPI bootloader finishes -- BOOTCOMPLETE asserted, which switches CPLD to DSP booted state (no DSP code needed)
  • Read calibration/configuration data from I2C flash
  • Start NMPC task on core 1
  • Initialize UKF with default values from I2C flash/L2 SRAM (depending on startup mode)
  • Load sensor calibration data from I2C flash/L2 SRAM (depending on startup mode)
  • Initialize I/O board comms -- 2x internal UARTs with EDMA to/from L2 then a copy from L2 to L1 each frame.
  • Initialize CPU logging, update and control comms -- external UART with EDMA to/from L2 only, logged packets transferred from L1 to L2 at end of each frame
  • Initialize IPC structures -- single mutex-protected state structure, plus mutex-protected message queue (?) for control packets to and from NMPC system.
  • Enter infinite loop:
    • Store loop start TSCH/TSCL
    • DMA last I/O board packets from UARTs
    • Parse and validate packets
    • Apply sensor calibration
    • Convert sensor readings to metric units
    • Transform and sum redundant sensor readings into a single virtual sensor reading
    • Exclude/increase covariance for very implausible sensor readings
    • Set GPS position/velocity covariance based on fix type
    • Set UKF sensor values
    • Run UKF iteration
    • Get UKF output state
    • Acquire global state mutex, copy from L1 state to global state, release global state mutex
    • Copy current state and raw I/O board packets to L2 CPU UART buffer, initiate DMA to external UART
    • Acquire global control value mutex, copy from global control value to L1 control value, release global control value mutex
    • Copy control values to L2 I/O board UART buffers, initiate DMA to internal UARTs
    • Acquire global I/O board command mutex, copy from global I/O board command to L2 I/O board UART buffers, release global I/O board command mutex, initiate DMA transfer to internal UARTs
    • Acquire global DSP command mutex, copy from L2 DSP command buffer to global DSP command buffer, release global DSP command mutex
    • Check difference between current TSCH/TSCL and loop start TSCH/TSCL; if > 1M enter reset

IPC globals:

  • AHRS state structure
  • DSP command buffer (CPU -> DSP, read by AHRS, handled by AHRS or NMPC)
  • NMPC state structure
  • System state structure


  • CPU->DSP: waypoint update, AHRS or NMPC parameter update
  • DSP->CPU: I/O board packet mirror, nav state estimate, system state
  • I/O board->DSP: sensor update
  • DSP->I/O board: control update


Flight control system firmware for the SFWA CPU board DSP (TMS320C6657) and CPLD (EPM1270)




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