View source for Open Access v4 Specs and Ratings

===Electrical Specs and Ratings===

<B>Power</B>
* 11-14VDC input, 1.5A self-resetting fuse
* 5V, 2A (absolute max) PSU on-board. 
* 2x200ma 12V accessory power ports (fused)
* 2x200ma 12V RFID reader supplies (fused)
* 5V power available on RPi and LCD expantion ports (unfused)
<B>Connectors</B>
*Power: 5.00mm Phoenix screw terminal
*Alarm, RS485, Relays: 3.50mm Phoenix screw terminal
*Jumpers: .100
*ICSP: 2x3 .100
*RPi: 2x3 .100
*LCD: 2x8 .100
<B>Relays</B>
*4x1FormC Relays, rated to 5A at 30VDC or AC.
**Pinout: NO-Common-NC
<B>Alarm Inputs</B>
*Support analog input via Analog 0..3 pins
*Uses a 2.2K current-limited resistor, TVS diode for protection
*Has a 10K pull-up resistor to +5V
*Pinout: 1. Input 2 Ground
*Usable sampling range: 0-4.1VDC. The protection and pull-up circuit form a 10K/2.2K divider.
*Additional "Tamper" zone, which is a digital input, same configuration
<B>RFID Inputs</B>
*Standard Wiegand26 inputs (GND, +12V, D0, D1, LED, Buzzer)
*Same 2.2K/10K protection as Alarm inputs
*D0,D1 pins are interrupt-driven (uses PCATTACH library for additional interrupt support)
*2.2K current-limited on LED/buzzer outputs

<B>CPU</B>
*Atmega328P at 16.00Mhz 
*Comes pre-loaded with Arduino Bootloader
*Compatible with "Duemillenova" Arduino
*Uses FTDI FT232L USB chip and mini-USB
*Includes ICSP header (6-pin) and reset switch
<B>RS485</B>
*On-board hardwre RS485 chip (TI SN65HVD)
*Connected to D6 (EN), D7 (RX), D8 (TX). 
*Use with SoftwareSerial library for interactive readers, chaining boards together in a bus
<B>Real-time clock</B>
*DS1307 RTC with CR-2032 backup battery
*5 year+ battery life

<B>Further Details</B>
*[[File:Open_Access_v4_schematic.pdf‎]]
*[[EM4100 Reader pinouts]]