Frequently Asked Questions
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v3 of VHS door control is the first to be used at 270 E 1st Ave
There are several components the access reader, the lock control and the RPi based control.
The lock control and monitoring is done by an Arduino Diecimila with opto-isolated relays attached. The schematic is shown below. The lock handle is engaged by the existing bidirectional motor. When not energized the relays pass control through to the motor from the keypad operated controller built in to the lock. Each relay drives the motor in a different direction, there is no limit switch, the control is time based. To allow someone to open or close the door, the lock is engaged for a period of time and then disengaged. The relay optoisolators are connected to P2 and P3, not P1 and P2 as shown in the schematic.
An additional optoisolator connected to P4 is used to provide feedback on the position of the door bolt, this is used for logging purposes only.
The access reader is connected the RPi via USB serial converter and is controlled/monitoring via ascii strings over the serial port.
The serial converter is an FTDI 4232H USB to quad serial converterPDF. It is wired for bus power as per the data sheet
USB Bus-powered: 1) Connect VBUS to VCC (CN3, pin 1 to CN3, pin 3). This connection takes the power from the USB bus (VBUS) and connects it to the voltage regulator input on the FT4232H Mini Module. The voltage regulator, in turn, provides V3V3, VPLL and VUSB power inputs to the FT4232H chip. 2) Connect V3V3 to VIO (CN2, pins 1, 3 & 5 to CN2, pins 11 & 21 and CN3, pins 12 & 22). This connection provides the correct 3.3VDC operating voltage for VCCIO on the FT4232H chip.