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Interfacing IL2000 System to Analogue World
Posted by Klug Christoph on 13 Aug 2001, 2:17 p.m.
Despite it being the year 2001, activities with the IL2000 system goes on, connecting HP-41 handheld computer and the HP-IL Interface-Loop to the future. The new ANA2000 module expands the IL2000 hardware board family, adapting its nice interface system to analogue world ! ANA2000 is a multi channel converter module which includes 8 analog input lines plus 8 analog output lines. For all analog I/O channels the voltage range is plus/minus 10V with 12 Bit resolution.
For ADC I use the proven 12 Bit analog digital converter design from I/O-Board, the ADS7800 from Burr&Brown (with internal sample & hold, reference voltage and oszillator). For ANA2000 board I added an 8-channel multiplexer front-end by using two AD7511 from Analog Devices (with latch-proof input lines).
Also for DAC, I take chips from Burr&Brown - two quad converter DAC4813 (with internal data-latches and reference voltage). Setting output voltages is possible independently for any channel or simultaniously for all channels by transfering individual bytes or the complete byte stream pattern by HP-41 control software.
Addressing the input multiplexer and the DAC´s is done by secondary addressing, this was used for the first time by the IL-Rack (I/O-Board manual IIX.21) and later by IL-Messlab (I/O-Board manual page IIX.25). Primary addressing is done by the well known control functions OUT1, OUT2. These commands select one hardware board like DIG2000 (16 bit digital input/output), I/O2000 (adapter board for using plug in module family from I/O-Board) and now the new ANA2000 board. The needed hardware for primary addressing is placed on the IL2000 interface board.
16-bit output data word A A A A . X X X X . X X X X . X X X X 4 address bits 12-bit data wordFor realizing secondary addressing I split the transferred 16-bit output word in a 12-bit data word plus a 4-bit address word (the highest significant nibble). Using these 4-bits makes possible the ability to sub-addressing four, 12-bit data latches directly and, with additional address decoder hardware, up to 16 different address lines. For the ANA2000 module, two 3 to 8 line decoders, 74HC138, set the needed address lines for the multiplexer and the DAC´s.
The most significant 4 bits of each 16-bit input data word can be used as an optional 4-bit digital input word. In this case, you need additional software which splits digital input word from the 12-bit ADC analogue data word. Normally, the highest 4-bits are not used, so jumpers set the input lines to GND.
The complete ANA2000 board has a max power consumption of nearly 3 Watts, delivered by a low drop voltage regulator and the DC/DC-Converter from the POW2000 board. If you need two ANA2000 boards for a larger application (i.e. 16 analogue I/O channels) then mount the optional DC/DC-Converter onto the POW2000 board and wire belonging power supply lines to the second ANA2000 board !
If you are HP-41 enthusiast and like to actively work with HP-IL, then I recommend the nice IL2000 system as a proven, battery-powered hardware plattform. In short time you can realize your individual interface solutions, such as measurement and control applications to and from the digital and analogue world. For more detailed information now read the expanded IL2000 manual. To get this, the I/O-Board manual, parts or finished and tested interface units than please contact the author :
Christoph Klug, Körnerstrasse 47 B, 31141 Hildesheim, Germany email : email@example.com
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