osEvent Thread::signal_wait(int32_t signals, uint32_t millisec) {
    uint32_t res;
    osEvent evt;
    uint32_t options = osFlagsWaitAll;
    if (signals == 0) {
        options = osFlagsWaitAny;
        signals = 0x7FFFFFFF;
    }
    res = osThreadFlagsWait(signals, options, millisec);
    if (res & osFlagsError) {
        switch (res) {
            case osFlagsErrorISR:
                evt.status = osErrorISR;
                break;
            case osFlagsErrorResource:
                evt.status = osOK;
                break;
            case osFlagsErrorTimeout:
                evt.status = (osStatus)osEventTimeout;
                break;
            case osFlagsErrorParameter:
            default:
                evt.status = (osStatus)osErrorValue;
                break;
        }
    }
    evt.status = (osStatus)osEventSignal;
    evt.value.signals = res;

    return evt;
}

Thread::signal_wait seems to be erroneous: <<code title=Thread.cpp>> osEvent Thread::signal_wait(int32_t signals, uint32_t millisec) { uint32_t res; osEvent evt; uint32_t options = osFlagsWaitAll; if (signals == 0) { options = osFlagsWaitAny; signals = 0x7FFFFFFF; } res = osThreadFlagsWait(signals, options, millisec); if (res & osFlagsError) { switch (res) { case osFlagsErrorISR: evt.status = osErrorISR; break; case osFlagsErrorResource: evt.status = osOK; break; case osFlagsErrorTimeout: evt.status = (osStatus)osEventTimeout; break; case osFlagsErrorParameter: default: evt.status = (osStatus)osErrorValue; break; } } evt.status = (osStatus)osEventSignal; evt.value.signals = res; return evt; } <</code>> When a osFlagsError occurs, evt.status is written, but the break afterwards jumps to evt.status = (osStatus)osEventSignal; A return statement before the closing } if-bracket would solve the problem (maybe clear evt.value.signals to 0 first).