Per-chirp T/R switching is owned by the FPGA plfm_chirp_controller
driving adar_tr_x pins (TR_SOURCE=1 in REG_SW_CONTROL, already set by
initializeSingleDevice). The MCU's SPI RMW path via fastTXMode/
fastRXMode/pulseTXMode/pulseRXMode/setADTR1107Control was:
(a) architecturally redundant — raced the FPGA-driven TR line,
(b) toggled the wrong bit (TR_SOURCE instead of TR_SPI),
(c) in setFastSwitchMode(true) bundled a datasheet-violating
PA+LNA-simultaneously-biased side effect.
Removed methods and their backing state (fast_switch_mode_,
switch_settling_time_us_). Call sites in executeChirpSequence /
runRadarPulseSequence updated to rely on the FPGA chirp FSM (GPIOD_8
new_chirp trigger unchanged).
Tests: adds CMSIS-Core DWT/CoreDebug/SystemCoreClock stubs to
stm32_hal_mock so F-4.7's DWT-based delayUs() compiles under the host
mock build. SystemCoreClock=0 makes the busy-wait exit immediately.
Jason
25a280c200