LightSafer User Guide

LightSafer is a tiny, silent hotel safe alarm - read all about it on the LightSafer home page.

Contents

  1. Turning on
  2. Arming
  3. Armed
  4. Alarm
  5. Notes
  6. Changing the PIN

Turning on

With LightSafer turned off, press the joystick in for a couple of seconds. Three green LEDs will light.

The LEDs will then indicate the battery level, from low (one LED on the left) to high (all 6 LEDs lit). You can expect a good few hours' battery life in the armed state when only one LED is lit. If no LEDs illuminate then the battery should be replaced. The image below shows 4 LEDs lit, so this LightSafer has a bit less than full battery level.

One LED means that the voltage is below 2.7V, and you should change the battery.

LightSafer battery level

LightSafer is now in a standby state with one green LED lit. It will turn back off after 30 seconds of inactivity, to preserve battery life.

LightSafer standby state

Arming

When in the standby state, arm the device by pressing the joystick in once. The red and green LEDs light:

LightSafer arming

You now have 20 seconds to put LightSafer in your safe (or other dark place you want to protect!). Press the joystick in again before the end of the 20 seconds to cancel the arming state and go back to standby.

Armed

Once LightSafer is armed, the red 'armed' LED will briefly illuminate, before all LEDs turn off, saving power whilst armed. You won't see this happen because you'll have closed up your safe, or zipped your bag up.

Triggered!

As soon as LightSafer sees a small amount of light, it will light up the red and green LEDs and request your PIN - you now have 30 seconds, or 3 attempts to input the correct PIN. To enter the pin, use the up (1), right (2), down (3) and left (4) directions on the joystick. For example, to enter the PIN of 12341234, enter up, right, down, left, up, right, down, left.

LightSafer - enter PIN

If you get the PIN wrong, the following LEDs light:

LightSafer wrong PIN

You then get another go at entering the correct PIN. If you get the PIN right then you'll be shown your safety code.

This is really important! This is a random set of LEDs that is unique to each device. It is shown to you every time you disarm the device. Because the LEDs are unique to each device, it allows you to check that nobody has reprogrammed your device, or switched it for another one. If the safety LEDs shown to you ever change then your device has been tampered with. You will only ever see the safety LEDs when you enter the correct PIN to disarm the device.

If you get the code wrong three times, or take more than 30 seconds to enter a code then Lightsafer will enter the alarm state.

Alarm

The alarm state looks like this:

LightSafer wrong PIN

You will be in this state if LightSafer had previously been armed, then triggered by a small amount of light, then the correct PIN wasn't entered. You can work out how long ago the alarm was set off by briefly pressing the joystick in. The right red LED will flash once for each 15 minute period since the alarm was triggered. For example if it were triggered an hour ago, the LED would flash 4 times.

To get LightSafer out of the alarm state, press and hold the joystick for a few seconds, then enter the correct PIN and you'll be back in the standby state.

Notes

  1. The state is preserved in the non-volatile EEPROM. Once the alarm has been triggered, there is no way that it can be reset without either entering the correct PIN, or reflashing the PIC (and therefore resetting the PIN back to 11111111).
  2. If you've forgotten the PIN then reflashing the PIC is the only way to make LightSafer usable again. Your current PIN will be lost.

Changing the PIN

You can change the PIN from the default (11111111) using the following method:

  1. Ensure LightSafer is either turned off or in standby (i.e. not armed or alarming)
  2. Remove the CR2032 battery
  3. Whilst pushing the joystick in, insert the battery. The LEDs will light:

    LightSafer PIN change again

  4. Enter the new PIN, the following LEDs will light:

    LightSafer PIN change reenter PIN

  5. Re-enter the new PIN. If it matches then all three green LEDs will flash twice, indicating that the PIN has been changed successfully. If the green LEDs don't flash then the PIN hasn't been changed. Either way, you will go back to the standby state.
  6. PINs must be exactly 8 digits in length.

Andy C
May 2025
andy@burningimage.net