Power door lock for ZAZ Tavria based on iButton
Since ZAZ Tavria car has possibility of locking door without a key, it is possible to build a simple power door lock which uses iButton DS1990C and only unlocks doors. In this case it is possible to use single power MOSFET instead of relay.
Power door lock is built with Atmel MCU ATTINY13A and uses iButton DS1990 keys. Parts of the lock placed into the case of plotter cartridge. Power MOSFET in D2PAK case mounted on soldering side of PCB. It is easy to get such MOSFETs from used PC motherboards or video cards. It is possible to use any MOSFET which opens with logic level and has minimal Vdrain-source not less than 20 V
It is possible to use single power door lock in the car, as well as two of them - one per door, what is more reliable. Sockets can be made of old door lock cylinders. It is not required to attach power ground to the socket directly, but in any case power ground must be connected to the door with wire, since contact through door hinges is not good enough. Bolt clamps were used to attach wires to the device, but appeared it would be more handy to use other kind of connectors to attach wires more easy in hard-to-reach places. Resident write/erase button is not necessary as rare used.
Power door lock function algorithm:
- Attaching known key to the socket leads to the opening pulse of 0.1 sec (experimentally selected), after one it is tested if the key was detached with 0.5 sec delay. If the key was detached the device goes into the initial state, otherwise it is testing again.
- Attaching unknown key to the socket leads to the alarm pulse of 0.1 sec (alarm line is connected to the "ground"), then after 0.5 sec delay device goes into initial state.
- Keeping write/erase button pressed about 10 sec leads to erasing all keys from device memory, after it an opening pulse is produced to indicate the end of operation.
- After pressing write/erase button and attaching a new key to the socket it is stored into the device memory, the end of operation is indicated with opening pulse. Eight keys may fit into the device memory. Writing keys will not duplicate them in memory. If the device memory is already full the opening pulse is produced anyway, thus it is necessary to check if new key opens the door. If not then it means the device memory has no room for the new key.
Warning: this power door lock does not give any warranty against stealing! Use many protections at once!
Download firmware