General Purpose Analog and Digital I/O Module for PC/104 Bus

GPIO-104 GPIO-104

  • Stock Number:

  • 100-7602

  • Budgetary Pricing:

  • $327.00 / 001 - 009
  • Contact us for More Quantity Discounts

  • Typical Lead-Time:

  • Stock - 4wks

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The GPIO-104 is an 8-bit analog and digital input/output module designed to satisfy a broad range of applications. Its generous assortment of functions and capabilities will, in many instances, make the GPIO-104 the only peripheral module required. It conforms to the PC/104 standard, operates on just +5V power, and uses a single 50-Position IDC header for all off-board I/O signal connections.

Analog Inputs

Eight 12-bit single-ended analog inputs are provided, each with software programmable input ranges of ±10V, ±5V, +5V, +10V. This capability effectively increases the dynamic range to 14-bits when employing software range-switching techniques. Input protection handles applied voltages up to ±16.5V and continues to function even when power is off. In addition, a fault condition on any input channel will not affect the operation of the remaining channels.

A special feature of the Analog-to-Digital Converter is its ability to allow the separate acquisition and conversion times be individually controlled by the user's software or automatically sequenced by the GPIO-104 hardware. Overall timing is precisely maintained by a crystal oscillator.

Analog-To-Digital conversions are initiated by writing a control byte which selects the input channel and sets its range along with other parameters. The host can determine when the conversion is complete using one of three methods: by simply waiting longer than the conversion time, by polling a status flag or by having the status flag interrupt the host when it becomes set. The resulting 12-bit value is read as two bytes in an 8+4 format.

Analog Outputs

The four 12-bit analog outputs are individually hardware programmable to provide one of three popular output ranges: ±5V, +5V, +10V. An on-board DC/DC converter enables the bipolar and +10V ranges to be achieved even though the GPIO-104 operates using only the PC/104 Bus +5V power supply.

The GPIO-104 includes the capability of having all the outputs update simultaneously by means of a single software write command. Those channels pre-loaded with new data will change, while the remaining channels maintain their previous output voltages glitch-free. This feature is particularly useful in applications which can not tolerate phasing errors between the outputs. The 12-bit data is loaded into the DACs using an 8+4 bit format.

Digital I/O

An industry standard 82C55 Programmable Peripheral Interface chip provides 24 digital channels across three 8-bit ports. This device offers very flexible configuration, including software programmable port directions and strobed handshaking. Each channel has a 10k pull-up resistor and defaults to logic "1" and input mode during system reset.


  • Analog I/O and Digital I/O in a single low-cost module
  • Eight 12-bit multi-range analog inputs (±10V, ±5V, +5V, +10V)
  • Up to 100ksps throughput, self-timed or user-controlled acquisition
  • Four 12-bit multi-range analog outputs (±5V, +5V, +10V)
  • 24 digital Input/Output channels using familiar 82C55 chip
  • Interrupts fully support sharing and access to all PC/104 bus IRQs
  • Single +5 volt power requirement



Analog Inputs
General:One MAX197 DAS chip provides eight multi-range single-ended analog input channels
A/D Resolution:12-bit (1 in 4096 of full-scale), 14-bit effective dynamic range using software range-switching techniques
Input Range:Each channel has software programmable input range: ±10V, ±5V, +5V or +10V
Overvoltage:±16.5V protection. A fault condition on any channel will not affect readings on other channels
Sampling:100,000 samples/sec max. (Host dependent), self-timed or user controlled acquisition
Analog Outputs
General:Two AD7237 chips provide four multi-range analog output channels. Supports simultaneous updates
D/A Resolution:12-bit (1 in 4096 of full scale)
Output Ranges:Each channel has jumper selectable output range: ±5V, +5V or +10V
Output Current:±5mA max. per output
Settling Time:8μs max. to within ±1LSB of final value
Relative Accuracy:±1LSB
Nonlinearity:Less than ±1LSB, guaranteed monotonic
Digital I/O
General:One 82C55 chip provides 24 digital I/O channels across three 8-Bit ports. Supports modes 0, 1 and 2
Compatibility:TTL/CMOS levels. Each channel is capable of sourcing or sinking 2.5mA, 10k pull-up on each channel
Addressing:8-bit PC/104 bus. Jumper selectable for any 16 byte block in hosts I/O map, 0x00016 through 0x3f016
Interrupt:One interrupt, Jumper selectable IRQ 3,4,5,6,7,9, (10,11,12,14,15)* or Disable. Supports sharing. Used by Analog-to-Digital converter and positive level sensitive external interrupt. * Optional 20-Position J2/P2 stack-through connector required for upper IRQs
Power Requirement:+5Vdc ±5% @ 340mA typical, unloaded outputs
Dimensions:PC/104 compliant, 3.55"W x 3.77"L. 8-bit stack-through, optional 16-bit stack-through
Environmental:Operating temperature: -25°C to 65°C (Standard)
Non-condensing relative humidity: 5% to 95%
Compliance: RoHS, Lead-Free
CA Residents: Warning - Prop 65 Info
Product Origin:Designed, Engineered, and Assembled in U.S.A. by SCIDYNE Corporation using domestic and foreign components.

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