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  • PC Analog Interface Unit

  • Created: Jul 18, 2016

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This Analog Interface Unit (AIU) is designed to allow a standard PC to interface to analog system. It is eminently suitable for applications such as data logging, data acquisition, and connection to sensors and transducers. It is suitable for almost any application that requires an easy customizable 8-bit ADC and/or DAC. It has been designed specifically for custom development applications, and complete driver routines are provided in BASIC, Pascal & C programming. All routines are DOS based and these allow the user to easily create customized applications for the AIU under multiple programming languages.

The circuit is comprised of a 9-bit analog I/O system, serial shift register, a quad 2 input multiplexer and a switching regulator. It specifically uses the TC7660SEOA713 super charge pump DC-to-DC voltage converter of Microchip. It converts a +1.5V to +12V input to a corresponding -1.5V to -12V output using only two low-cost capacitors. This circuit is supplied by a 5V split supply. It has also a parallel port for PC and can be run through the AIUTEST.EXE program. This program will first detect the AIU and display what port it is connected to. It will then proceed to test the data port for correct operation. It will also require a loopback connector on the input and output of the AIU where each range is then tested for all possible voltage values. The range selected applies to both the analog input voltage of the ADC and the output voltage from the DAC. If the AIU is not detected then the most likely problem will be with the unit's construction.

The Analog Interface Unit (AIU) is a simple circuit that connects to a PC parallel port, and allows you to sample and output 8-bit analog signals under software control. It features an 8-bit ADC and DAC with 1MΩ ADC input impedance allows use of standard x10 adapters. It is powered entirely from the PC’s parallel port with stable onboard voltage reference.



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