AirSpy firmware directory structure and software architecture

• airspy_m0 directory contains code for M0 core and it manages (file airspy_m0.c):

  • Boot initialization (function main) manages:
    • USB init
    • M0 core IRQ (USB0 & M4 Core)
  • R820T
    • Manage R820T depending on USB command see airspy_usb_req.c function
  • Communication with M4 core
    • It is done through M4 core IRQ function m4core_isr and just acknowledge M4 IRQ
  • Settings depending on Sample Rate and containing R820T BW conf are stored in file firmware/common/airspy_xxx_conf.c with xxx corresponding to board model name.
  • Main loop main function just check shared "data offset" to transfer the data over USB.
  • USB command/answer are managed through airspy_usb_req.c function
    • Main USB manager is usb_vendor_request() which dispatch all commands supported and defined in airspy_usb_req_init()

• airspy_m0s directory contains code for M0s core (file airspy_m0s.c):

  • M0s is free for custom firmware (it is disabled and shall be enabled, see main in airspy_m4.c).

• airspy_m4 directory contains code for M4F core and it manages (file airspy_m4.c):

  • Boot initialization (function main) manages:
    • Pin setup
    • System clock init
    • M4 core IRQ (DMA & M0 Core)
    • ADC init
    • Boot M0 core
  • Analog to digital conversion (ADC)
    • Managed through dma_isr function, it mainly manages:
      • Some error/performances statistics
      • Update data offset (corresponding to ADC data read from DMA) shared with M0 core
  • Communication with M0 core
    • It is done through M0 core IRQ function m0core_isr and manages:
    • Commands from M0 in order to Start/Stop ADC and change Sample Rate
  • Settings for Init, ADC, SI5351C are stored in file firmware/common/airspy_xxx_conf.c with xxx corresponding to board model name.
  • Main loop main function do nothing except entering in low power mode(Wait For Event).

• airspy_rom_to_ram directory contains:

• m0, m0s and m4 built together in final firmware airspy_rom_to_ram.bin

• usbprog_airspy directory contains tools to flash the firmware through USB firmware mode (only for Windows)

• dfuprog_airspy directory contains tools to flash the firmware through USB DFU/Recovery mode (only for Windows)

• common directory contains code for M0 or M4 core and specific to AirSpy hardware:

  • It contains mainly drivers:
    • CORE mainly dedicated to LPC4370
    • R820T
    • SI5351C
    • USB
    • SPI Flash(W25Q80BV/S25FL032P)

• libopencm3 directory contains mainly code for M0, M0s or M4 peripherals/boot

• scripts contains Python scripts mainly to retrieve FW version from git release

In this architecture the main manager is the M0 core mainly because it manage USB answer/reply in order to be as low power as possible and to let M4F core free for future features.