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The Gecko
   

 

The Gecko is an open-source microcontroller system
based on a processor board with built in provision for
simple networking, mass storage and graphical displays.

 

The Gecko has the following features.

  • Arduino Mega 2560 compatible
  • Accommodates Arduino Duemilanove shields
  • Buffered LED13
  • Power failing interrupt with optional external super cap for VCC hold up
  • On board supercap backup for MCU, SRAM and RTC
  • Allowance for HV programming in case ISP gets bricked
  • USB interface on Serial0 using FT232 chip, jumper enabled auto reset
  • USB port protected from ESD
  • Piezo buzzer
  • 256k x 8 external SRAM (4 x 64k pages), supercap backed
  • 4D Systems 5-pin interface for LCDs/OLEDs/microSD etc
  • Ambient enclosure temperature readable from RTC
  • Provision for two Geckos to run as SPI-coupled dual processors

IO

  • 47 hardened IO lines, good for ±30v and over-current protected
  • IO can be used as GPIO or serial, timers, analogue, PWM etc same as Mega
  • All IO connected to GVS (GND, Volts, Signal) 3-pin headers
  • IO connections on two "wings" that are mounted at right angles to the main PCB

Mechanical

  • Designed to fit inside Hammond 1455N1201 enclosure
  • IO wings become end panels for enclosure
  • Custom IO wings easily made
  • PCB cutouts allow cables to run out the rear of the enclosure for bulkhead mounting
  • Mounting holes to match 4D Systems uLCD-32 display
  • Reset and power buttons located on side of PCB, can be activated through hole in side of enclosure

Connectors

  • ISP header
  • SPI header for dual processing
  • JTAG header
  • AVRmon header (my own monitor)
  • USB mini B
  • 39 x 3-pin GVS headers for IO
  • 4 x 4-pin headers for serial ports (power and signals)
  • 1 x 4-in header for I2C (power and signals)
  • 2 x JST connector for EM406 GPS
  • Header for remote power on/off pushbutton
  • Header for remote LED indicator
  • RJ45 8/8 socket

I2C

  • Buffered SDA and SCL available on screw terminals and IO wing

RS-485

  • Solder-bridge selectable 120R termination resistors
  • Solder-bridge selectable 2-wire (half duplex) or 4-wire (full duplex)
  • Solder-bridge selectable 560R bias resistors
  • Connection to RJ11 8/8 socket through patch panel
  • Patch panel has access to various power options for power over network
  • Rx/Tx swappable under program control for auto polarity detection
  • ESD protection

RS-232

  • MAX232 chip
  • 4 full spec signals, Tx, Rx, plus one control in and one out

Serial in general

  • Screw terminal blocks for all RS-485 and RS-232 signals
  • Patch panel allows any combination of RS-485 and power signals to be connected to an on-board RJ45 8/8 socket

RTC

  • On-board TCXO, very accurate
  • 32kHz interrupt to MCU
  • Alarm interrupt to MC


Power supply

  • Fused
  • Varistor protection against over voltage
  • Polarity independant (schottky diode bridge)
  • On-board or remote push buttons can turn on
  • RTC can turn on
  • MCU can turn off under program control
  • MCU can turn on under program control (ie on RTC interrupt)
  • VCC from regulator or USB (no control of PSU if using USB source)
  • 30V tolerant VIN with no heatsink (1A)
  • VIN level monitoring by MCU

 

   
 

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Copyright © 1973-2013 Rob Gray, All rights reserved.
PO Box 450, Gin Gin, QLD, Australia.
www.robgray.com