Issues with v2.0

First off, the v2.x hardware has been very reliable and is installed at a number of locations.

The system at 23b Shop has been in production for over 1 year with no issues.

There are some quirks to this system however, especially since it was designed without ever having seen a commercikal unit.

Separate power or ground for each sensor input (1 sensors = 2 screw terminals)
Consistent labeling (some items start with 0, others with 1)
Screw terminals obscure labels of pinouts.
Standardize Wiegand and other pin layout and order
Removable screw terminals (3.5 or 5mm) desirable for servicing
Need to label NO, C, O for relay terminals
Increased separation of trace spacing near relays
Double ground planes need stitch vias for better immunity
Eliminate ground plane around external relay traces
Readers with <100uS pulses require external capacitors to work
Break out ICSP pins from Arduino
Consider adding an Arduino reset switch footprint
Grounded components hard to solder. Consider going to a grid for ground plane
Better regulator footprint or more spacing for heatsink
Need more inputs and outputs for Wiegand reader beeper, LEDs
Consider Arduino Mega support
Look at RTC crystal and pick best temperature-compensation range
Think about on-board Ethernet
Option for RS-485
Option for SD card for local logging. Consider file system.
Control costs (SMT design, cheaper components in some areas
- Switching PSU circuit
- Replace opto-isoloators with ESD absorbing devices. May also allow bi-directional support.
Consider CPU that will handle encryption
Design Requirements
Detailed Specification

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