typedef struct {
    uint32_t timestamp;
    uint8_t  messageType;
} InterruptMessage;

static void interruptButton(EXTDriver *extp, expchannel_t channel) {
  (void)extp;
  (void)channel;
  if (thread != NULL) {
      chSysLockFromIsr();
      palSetPad(GPIOB, 8);
      InterruptMessage message;
      message.timestamp =  10002;
      message.messageType = tmButton; // 1
      chMBPost(&mb[1], (msg_t) &message, TIME_IMMEDIATE);
      palClearPad(GPIOB, 8);
      chSysUnlockFromIsr();
  }
}

static void interruptRotation(EXTDriver *extp, expchannel_t channel) {
  (void)extp;
  (void)channel;
  if (thread != NULL) {
      chSysLockFromIsr();
      palSetPad(GPIOB, 8);
      InterruptMessage message;
      message.timestamp =  10001;
      message.messageType = tmRotationSignal; // 2
      chMBPost(&mb[1], (msg_t) &message, TIME_IMMEDIATE);
      palClearPad(GPIOB, 8);
      chSysUnlockFromIsr();
  }
}

static msg_t Thread(void *arg) {
...
    InterruptMessage *interruptMessage;
    thread = chThdSelf();
...
    while (true) {
        // sleep and wait for message
        chSysLock();
        chMBFetch(&mb[1], (msg_t*) &interruptMessage, TIME_INFINITE);
...
        chSysUnlock();
  }
}