Developing Panipuri Water Vending Machine Controller

 Panipuri water vending machine controller is new product I am working actively, The water will dispense when proximity sensor is triggered and chutney mixed water must keep mixing so that solid particles in water does not settled down to bottom which dilutes the tase of panipuri water.

So I designed a circuit with 2 MOSET outputs one is for Vending The Water and another for Mixing The Water, system operates on 12V DC and has +5V Regulator onboard for Microcontroller and Proximity Sensor. 

Real challenge was to develop it on cheapest microcontroller to put cap on final pricing, also the controller must have EEPROM to store some parameters.

Controller has 2 Buttons to adjust Dispensing Quantity which is proportional to Time, and Pressure of Dispensing Motor which I achieve using PWM Duty Control based MOSFET Driving. These settings are kept in EEPROM and Recall after every power-up.

PCB is double Side PTH as it is very smaller and have some SMD Components. It Cost around 35 INR in bulk manufacturing. 

All in all I spent whole 2 days in its coding and finally it worked like charm, but before that it had issue with Mixing Motor. The MOSFET of Mixing Motor keeps turned on even pin connected to it is at logic 0
it took some time to resolve and solution was right in the datasheet of microcontroller, The pin is shared with its ICSP (In Circuit Serial Programming) Connection. so i turned it of using core SFR's and it worked like charm. 

Also as I was soldering PCB's I realize I have connected Biasing Resistor to Drain of MOSFET instead of 12V Rail. but before starting to program it I just cut the track and added a jumper wire to right location.

This is the photo I took while debugging the board.




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