model DA_Converter "Simple digital to analog converter"
import L = Modelica.Electrical.Digital.Interfaces.Logic;
Modelica.Electrical.Digital.Interfaces.DigitalInput trig "Trigger input"
annotation (Placement(
transformation(extent = {
{-10, 92},
{10, 112}}),
iconTransformation(
extent = {
{-10, -10},
{10, 10}},
rotation = -90,
origin = {0, 100})));
Modelica.Electrical.Digital.Interfaces.DigitalInput x[N] "Digital input"
annotation (Placement(
transformation(extent = {
{-110, -10},
{-90, 10}}),
iconTransformation(extent = {
{-110, -10},
{-90, 10}})));
Modelica.Electrical.Analog.Interfaces.PositivePin p "Positive electrical pin (output)"
annotation (Placement(
transformation(extent = {
{90, 90},
{110, 110}}),
iconTransformation(extent = {
{90, 90},
{110, 110}})));
Modelica.Electrical.Analog.Interfaces.NegativePin n "Negative electrical pin (output)"
annotation (Placement(
transformation(extent = {
{90, -110},
{110, -90}}),
iconTransformation(extent = {
{90, -110},
{110, -90}})));
SI.Voltage vout(start = 0, fixed = true);
Real y(start = 0, fixed = true);
parameter Integer N(final min = 1, start = 8) "Resolution - input signal width";
parameter SI.Voltage Vref(start = 10) "Reference voltage";
algorithm
when trig == L.'1' or trig == L.'H' then
y := 0;
for i in 1:N loop
y := if x[i] == L.'1' or x[i] == L.'H' then y + 2 ^ (i - 1) else y;
end for;
vout := y * Vref / (2 ^ N - 1);
end when;
equation
p.i + n.i = 0;
p.v - n.v = vout;
annotation (
defaultComponentName = "converter",
Documentation(
info = "<html>\n<p>Simple digital to analog converter with a variable input signal width of N bits. The input signal is an N-vector of type Logic (9-valued logic according to IEEE 1164 STD_ULOGIC). The output voltage of value <code>y</code> is generated by an ideal voltage source. The output can only change if the trigger signal <code>trig</code> of type Logic changes to '1' (forced or weak). In this case, the output voltage is calculated in the following way:\n</p>\n<pre> N\n y = SUM ( x[i]*2^(i-1) )*Vref/(2^N-1),\n i=1\n</pre>\n<p>where x[i], i=1,...,N is 1 or 0. and Vref is the reference value. Therefore, the first bit in the input vector x[1] is the least significant one (LSB) and x[N] is the most significant bit (MSB).</p>\n<p>This is an abstract model of a DAC. Hence, it can not cover the dynamic behaviour of the converter. Therefore the output will change instantaneously when the trigger signal rises.</p>\n</html>",
revisions = "<html>\n<ul>\n<li><em> October 13, 2009 </em>\n by Matthias Franke\n </li>\n</ul>\n</html>"),
Icon(
coordinateSystem(
preserveAspectRatio = true,
extent = {
{-100, -100},
{100, 100}}),
graphics = {
Rectangle(
extent = {
{-100, 100},
{100, -100}},
lineColor = {0, 0, 255}),
Polygon(
points = {
{-100, -100},
{100, 100},
{-100, 100},
{-100, -100}},
lineColor = {0, 0, 255},
fillColor = {127, 0, 127},
fillPattern = FillPattern.Solid),
Text(
extent = {
{-60, 50},
{60, 10}},
lineColor = {0, 0, 255},
textString = "%n-bit"),
Text(
extent = {
{-60, -10},
{60, -50}},
lineColor = {0, 0, 255},
textString = "DAC")}));
end DA_Converter;