Register `0x83`，This is a stroke/handshake/read gate register in the internal NVM/info read process. Not a regular ranging service register. In other words, the purpose of checking `0x83` here is to confirm that the device has completed the corresponding internal operation and is ready for the next step.
So, when a timeout happens on `0x83`, it usually means that the software is waiting for an **internal state transition** that did not occur within the expected time. This is why the code uses a timeout: without it, the polling loop could wait forever if the internal handshake never completes.
VL53L0X_Error VL53L0X_device_read_strobe(VL53L0X_DEV Dev)
{
VL53L0X_Error Status = VL53L0X_ERROR_NONE;
uint8_t strobe;
uint32_t LoopNb;
LOG_FUNCTION_START("");
Status |= VL53L0X_WrByte(Dev, 0x83, 0x00);
/* polling
* use timeout to avoid deadlock
*/
if (Status == VL53L0X_ERROR_NONE) {
LoopNb = 0;
do {
Status = VL53L0X_RdByte(Dev, 0x83, &strobe);
if ((strobe != 0x00) || Status != VL53L0X_ERROR_NONE)
break;
LoopNb = LoopNb + 1;
} while (LoopNb < VL53L0X_DEFAULT_MAX_LOOP);
if (LoopNb >= VL53L0X_DEFAULT_MAX_LOOP)
Status = VL53L0X_ERROR_TIME_OUT;
}
Status |= VL53L0X_WrByte(Dev, 0x83, 0x01);
LOG_FUNCTION_END(Status);
return Status;
}
The timeout (VL53L0X_DEFAULT_MAX_LOOP) is used because `VL53L0X_device_read_strobe()` is polling register `0x83` and waiting for the device to signal completion of an internal read-handshake sequence.
In this flow, `0x83` is not used like a normal configuration register. It acts as a synchronization or strobe register for internal device information access. After writing `0x83 = 0x00`, the code waits until the device changes it to a non-zero value, which indicates that the internal operation has completed.
If, for any reason, that internal state transition never happens, the polling loop would otherwise run forever. The timeout is therefore necessary to prevent the firmware from getting stuck in an infinite wait condition and to allow the API to return an error instead.
