Touch pad door lock
Jacob Smith.
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Overview
The door lock uses the MPR121 Capacitive Touch Pad by SparkFun as a means for entering key codes, and a solenoid door lock by Adafruit to simulate the door. First the user is prompted to enter their own personal pin code. Then a random number is generated as an authentication code, which can be sent to the user via SMS or another method. At this point, a new randomized authentication code is generated every 30 seconds, replacing the old code. For the purpose of this demo it is just printed on the PC serial port. Once the pin code and authentication code are entered, the door is unlocked. If a wrong pin code or authentication code are entered, the user is prompted to enter another code. In this code, there is no limit to how many incorrect codes can be entered, but that can be easily added.
Program
Import programECE4180_Touchpad_V2
touch pad door lock with two phase authentication
Last commit 24 Nov 2015 by Jacob Smith
Pinout
Touch Pad
| Touch Pad | mbed | |
| Vcc | Vout | |
| IRQ | p30 | |
| SCL | p10 | |
| SDA | p9 | |
| GND | GND |
Solenoid Door Lock
| Solenoid | mbed | Driver circuit (transistor) | 12V power supply | ||||
| GND | GND | GND | GND | ||||
| +V | - | +V | - | ||||
| - | - | +V | +12V | ||||
| - | p29 | base | - |
NOTE: two 4.7k resistors should be used between touch pad SCL and SDA, and another 1k resistor from p29 to driver circuit logical input
Images and Videos
Door lock driver circuit diagram (.pdf)
/media/uploads/jsmith352/solenoid_driver_wiring_diagram.pdf
Driver circuit photo
Door Lock
Touch Pad
Video Demonstration
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