It a simple electronic design using two 1,5V batteries and two Hall sensors. The system uses a ATtiny202 processor and has two Leds, it works as follows:
1. When the magnet is in range of hall sensors the leds are off. This is the “waiting mode” the unit needs to be in a sleep mode so it needs to switch on every 30 seconds for a few milliseconds to check the status of the hall sensors and voltage (this needs to be done to save battery life), as it is only two batteries and needs a shelf life of at least 5 years in sleep mode.
2. When the unit read that the magnet has passed the 1st hall sensor the Red Led needs to start flashing (if the magnet moves in range the Led must stop flashing and the unit must go back to sleep mode) Led needs to flash once every 3 seconds.
3. When the unit reads that the magnet has moved past the second hall sensor (it would also be past first one) the unit needs to flash the same red Led twice every 3 seconds. Again if the magnet moves within range of second hall sensor the unit must then only flash once for the first hall sensor.
4. The unit has jumper 1 (two pin) by bridging this jumper the unit is turned on after been installed, if the jumper is bridged again the unit switches off (option 1) or by bridging this jumper the unit is turned on after been installed thereafter the jumper has no roll the unit can never be turned off.
5. One the line voltage dropped to 1,9v the Amber Led will need to start flashing once every 5 seconds. (the voltage needs to be check at the same time as the hall sensors when the unit comes out of sleep mode every 30 seconds. Once low battery led flashes the unit must flash until it is dead.
6. The program must be password protected so that it cannot be copied after it is installed. We can use jumper 2 (three pin jumper to program). The unit, however the customer needs to be able to view a log file from these jumpers that shows the following, when unit was 1st switched on thereafter from that point there after we need to be able to tell how many hours went past before unit started flashing the Red or amber Led and for how long the Led flashed for. (the unit should in theory only flash 4 times, once it is switched on for first time, then once installed and tested and then once there is a fault, however it would be better to show more than only 4 logs. We are open to any suggestions on the log system.
7. We are using a Microchip MPLAB PicKit 4 programmer and MPLABX IDE 5.52 to program the unit and to read the logs.
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It's easy for me to control LED and read the Hall sensor, but please send a sample of the circuit board because I need it to debug the program. Thank you very much.