sim: mixed analog+digital +
+Legend: +
-
+
- error: supported in theory, but the simulation fails with an error +
- N/S: not supported +
- TODO: example not yet developed +
Model from the library
+ +Scope
++Mixed mode (analog + digital) simulation in time domain. + +
The schematics
++The input and the output of the circuit are analog, but there is a +section of digital circuity in between (a xor gate). The simulator +runs the analog sections in the normal fixed time stepping manner +while the digital section is simulated based on events. This makes +large digital circuits simulate much faster at the expense of tracking +digital lines only using low/high/unknown states, not simulating +transitions in details (rising/falling edges). +
+There are DAC and ADC converters inserted on the boundary of the +analog and digital systems, using terminal attributes. +
+
+Click the image to get the sch-rnd sheet
+More info on the circuit: www.electronics-tutorials.ws + +
Preparing for simulation
++The xor gate is going to use ngspice's internal model called d_xor. The whole +model card is specified within the symbol, using the +spice/model_card +symbol attribute. +
+ADC converters are installed on the input terminals of the xor gate by +setting the terminal attribute spice/bridge/model to bridge_adc_ttl, which +is an sch-rnd stock spice model for TTL levels. Whenever spice/bridge/model +is set on a terminal, target_spice will cut the original network connection +of the terminal to insert a bridge component there. This component is +not visible on the schematics, as it's specified in an attribute, but shows +up in the abstract model for any view using target_spice. +
+In case of ngspice, only one bridge component is placed per model, because +ngspice's bridge components can handle multiple inputs and outputs in an 1:1 +mapping. +
+(The sch-rnd user manual has more +details on bridging) +
+The same bridging is done on the output terminal with model brirdge_dac_ttl. +
+On the input, two pulses V1 and V2 are installed to generate trapezoid +signals with slow rising and falling edges. This is to demonstrate how ADC +goes from low to undefined to high. On the output a resistor is used +to provide a DC path from the terminal to the ground - spice usually +requires a DC path to the ground. + +
Raw spice commands
++This example executes a normal transient simulation. Since most signals +are either low or high most of the time, they would overlap on the plot. +To avoid confusion, slight y offsets are introduced using arithmetics, ++0.0n. +
+tran 10ms 6s +plot v(input1)+0.04 v(input2)+0.08 v(output) xlimit 0 6s ++ +
Export and run ngspice
++Running ngspice the usual way on the export yields the following graphs: +
+
+
+
Using other implementations
+gnucap
++Mixed mode simulation is not supported with gnucap. + +
xyce
+
+TODO
Index: trunk/doc/tutorial/simulation/raw/30_mixed.png
===================================================================
Cannot display: file marked as a binary type.
svn:mime-type = application/octet-stream
Index: trunk/doc/tutorial/simulation/raw/30_mixed.png
===================================================================
--- trunk/doc/tutorial/simulation/raw/30_mixed.png (nonexistent)
+++ trunk/doc/tutorial/simulation/raw/30_mixed.png (revision 7876)
Property changes on: trunk/doc/tutorial/simulation/raw/30_mixed.png
___________________________________________________________________
Added: svn:mime-type
## -0,0 +1 ##
+application/octet-stream
\ No newline at end of property
Index: trunk/doc/tutorial/simulation/raw/30_mixed.rs
===================================================================
--- trunk/doc/tutorial/simulation/raw/30_mixed.rs (revision 7875)
+++ trunk/doc/tutorial/simulation/raw/30_mixed.rs (revision 7876)
@@ -58,7 +58,7 @@
}
ha:group.13 {
uuid=39gOSGd8aSMOm1wdWfIAAAAF;
- x=96000; y=124000;
+ x=44000; y=96000;
li:objects {
ha:group.1 {
uuid=39gOSGd8aSMOm1wdWfIAAAAG; src_uuid=9bwyX4hVlbhQseMSDAAAAAAD;
@@ -121,7 +121,7 @@
}
ha:group.14 {
uuid=mHn79ppCTFm1QBmauQ0AAAAp; src_uuid=iNOQfJpO6hT/HFDFGjoAAABx;
- x=56000; y=108000; rot=270.000000; mirx=1;
+ x=16000; y=80000; rot=270.000000; mirx=1;
li:objects {
ha:arc.1 { cx=10000; cy=0; r=6000; sang=0.000000; dang=360.000000; stroke=sym-decor; }
ha:arc.2 { cx=8000; cy=0; r=2000; sang=0.000000; dang=180.000000; stroke=sym-decor; }
@@ -157,7 +157,7 @@
-sym-license-dist=GPLv2+
-sym-license-use=Public Domain
-sym-source=sch-rnd default symbol lib
- name=X1
+ name=V1
li:portmap {
{P->spice/pinnum=1}
{N->spice/pinnum=2}
@@ -169,7 +169,7 @@
}
ha:group.15 {
uuid=mHn79ppCTFm1QBmauQ0AAAAs; src_uuid=LnNTcUkV1CIzG7F2EXUAAAAZ;
- x=16000; y=0;
+ x=-24000; y=-28000;
li:objects {
ha:line.1 { x1=40000; y1=88000; x2=40000; y2=80000; stroke=wire; }
}
@@ -177,15 +177,9 @@
ha:role = { value=wire-net; prio=0; }
}
}
- ha:connection.16 {
- li:conn {
- /2/15/1
- /2/14/4/1
- }
- }
ha:group.17 {
uuid=mHn79ppCTFm1QBmauQ0AAAAt; src_uuid=iNOQfJpO6hT/HFDFGjoAAABm;
- x=56000; y=80000;
+ x=16000; y=52000;
li:objects {
ha:group.1 {
uuid=mHn79ppCTFm1QBmauQ0AAAAu; src_uuid=iNOQfJpO6hT/HFDFGjoAAABn;
@@ -213,15 +207,9 @@
role=symbol
}
}
- ha:connection.18 {
- li:conn {
- /2/17/1/1
- /2/15/1
- }
- }
ha:group.19 {
uuid=mHn79ppCTFm1QBmauQ0AAAAv; src_uuid=iNOQfJpO6hT/HFDFGjoAAABx;
- x=76000; y=108000; rot=270.000000; mirx=1;
+ x=36000; y=80000; rot=270.000000; mirx=1;
li:objects {
ha:arc.1 { cx=10000; cy=0; r=6000; sang=0.000000; dang=360.000000; stroke=sym-decor; }
ha:arc.2 { cx=8000; cy=0; r=2000; sang=0.000000; dang=180.000000; stroke=sym-decor; }
@@ -257,7 +245,7 @@
-sym-license-dist=GPLv2+
-sym-license-use=Public Domain
-sym-source=sch-rnd default symbol lib
- name=X2
+ name=V2
li:portmap {
{P->spice/pinnum=1}
{N->spice/pinnum=2}
@@ -269,7 +257,7 @@
}
ha:group.20 {
uuid=mHn79ppCTFm1QBmauQ0AAAAy; src_uuid=LnNTcUkV1CIzG7F2EXUAAAAZ;
- x=36000; y=0;
+ x=-4000; y=-28000;
li:objects {
ha:line.1 { x1=40000; y1=88000; x2=40000; y2=80000; stroke=wire; }
}
@@ -277,15 +265,9 @@
ha:role = { value=wire-net; prio=0; }
}
}
- ha:connection.21 {
- li:conn {
- /2/20/1
- /2/19/4/1
- }
- }
ha:group.22 {
uuid=mHn79ppCTFm1QBmauQ0AAAAz; src_uuid=iNOQfJpO6hT/HFDFGjoAAABm;
- x=76000; y=80000;
+ x=36000; y=52000;
li:objects {
ha:group.1 {
uuid=mHn79ppCTFm1QBmauQ0AAAA0; src_uuid=iNOQfJpO6hT/HFDFGjoAAABn;
@@ -313,18 +295,13 @@
role=symbol
}
}
- ha:connection.23 {
- li:conn {
- /2/22/1/1
- /2/20/1
- }
- }
ha:group.24 {
uuid=mHn79ppCTFm1QBmauQ0AAAA1;
+ x=-40000; y=-28000;
li:objects {
ha:line.1 { x1=76000; y1=108000; x2=76000; y2=116000; stroke=wire; }
- ha:line.2 { x1=76000; y1=116000; x2=96000; y2=116000; stroke=wire; }
- ha:text.3 { x1=80000; y1=116000; dyntext=1; stroke=wire; text=%../A.name%; floater=1; }
+ ha:line.2 { x1=76000; y1=116000; x2=84000; y2=116000; stroke=wire; }
+ ha:text.3 { x1=76000; y1=116000; dyntext=1; stroke=wire; text=%../A.name%; floater=1; }
}
ha:attrib {
name=input2
@@ -331,24 +308,13 @@
ha:role = { value=wire-net; prio=0; }
}
}
- ha:connection.25 {
- li:conn {
- /2/24/1
- /2/19/5/1
- }
- }
- ha:connection.26 {
- li:conn {
- /2/24/2
- /2/13/2/1
- }
- }
ha:group.27 {
uuid=mHn79ppCTFm1QBmauQ0AAAA2;
+ x=-40000; y=-28000;
li:objects {
ha:line.1 { x1=56000; y1=108000; x2=56000; y2=124000; stroke=wire; }
- ha:line.2 { x1=56000; y1=124000; x2=96000; y2=124000; stroke=wire; }
- ha:text.3 { x1=80000; y1=124000; dyntext=1; stroke=wire; text=%../A.name%; floater=1; }
+ ha:line.2 { x1=56000; y1=124000; x2=84000; y2=124000; stroke=wire; }
+ ha:text.3 { x1=76000; y1=124000; dyntext=1; stroke=wire; text=%../A.name%; floater=1; }
}
ha:attrib {
name=input1
@@ -355,23 +321,12 @@
ha:role = { value=wire-net; prio=0; }
}
}
- ha:connection.28 {
- li:conn {
- /2/27/1
- /2/14/5/1
- }
- }
- ha:connection.29 {
- li:conn {
- /2/27/2
- /2/13/1/1
- }
- }
ha:group.30 {
uuid=mHn79ppCTFm1QBmauQ0AAAA3;
+ x=-52000; y=-28000;
li:objects {
- ha:line.1 { x1=120000; y1=120000; x2=132000; y2=120000; stroke=wire; }
- ha:text.2 { x1=132000; y1=120000; dyntext=1; stroke=wire; text=%../A.name%; floater=1; }
+ ha:line.1 { x1=120000; y1=120000; x2=124000; y2=120000; stroke=wire; }
+ ha:text.2 { x1=124000; y1=120000; dyntext=1; stroke=wire; text=%../A.name%; floater=1; }
}
ha:attrib {
name=output
@@ -378,15 +333,9 @@
ha:role = { value=wire-net; prio=0; }
}
}
- ha:connection.31 {
- li:conn {
- /2/30/1
- /2/13/3/1
- }
- }
ha:group.32 {
uuid=Xb4Ih/E1Q5gK2yySOvUAAAAz; src_uuid=TeGEOMuew6iCb2kzckAAAAAD;
- x=36000; y=144000;
+ x=16000; y=116000;
li:objects {
ha:text.1 { x1=2000; y1=-4000; dyntext=0; stroke=sym-decor; text=raw spice; }
ha:text.2 { x1=2000; y1=-8000; dyntext=0; stroke=sym-decor; text=command; }
@@ -414,7 +363,7 @@
}
ha:group.33 {
uuid=GtwUPhB2CW+7+ykXMBQAAAAc; src_uuid=iNOQfJpO6hT/HFDFGjoAAABC;
- x=132000; y=120000; rot=270.000000;
+ x=72000; y=92000; rot=270.000000;
li:objects {
ha:group.1 {
uuid=GtwUPhB2CW+7+ykXMBQAAAAd; src_uuid=iNOQfJpO6hT/HFDFGjoAAABD;
@@ -462,15 +411,9 @@
value=100k
}
}
- ha:connection.34 {
- li:conn {
- /2/33/2/1
- /2/30/1
- }
- }
ha:group.35 {
uuid=GtwUPhB2CW+7+ykXMBQAAAAh; src_uuid=iNOQfJpO6hT/HFDFGjoAAABm;
- x=132000; y=80000;
+ x=72000; y=52000;
li:objects {
ha:group.1 {
uuid=GtwUPhB2CW+7+ykXMBQAAAAi; src_uuid=iNOQfJpO6hT/HFDFGjoAAABn;
@@ -500,6 +443,7 @@
}
ha:group.36 {
uuid=GtwUPhB2CW+7+ykXMBQAAAAj;
+ x=-60000; y=-28000;
li:objects {
ha:line.1 { x1=132000; y1=100000; x2=132000; y2=80000; stroke=wire; }
}
@@ -507,13 +451,73 @@
ha:role = { value=wire-net; prio=0; }
}
}
- ha:connection.37 {
+ ha:connection.42 {
li:conn {
+ /2/15/1
+ /2/14/4/1
+ }
+ }
+ ha:connection.43 {
+ li:conn {
+ /2/17/1/1
+ /2/15/1
+ }
+ }
+ ha:connection.44 {
+ li:conn {
+ /2/20/1
+ /2/19/4/1
+ }
+ }
+ ha:connection.45 {
+ li:conn {
+ /2/22/1/1
+ /2/20/1
+ }
+ }
+ ha:connection.46 {
+ li:conn {
+ /2/24/1
+ /2/19/5/1
+ }
+ }
+ ha:connection.48 {
+ li:conn {
+ /2/27/1
+ /2/14/5/1
+ }
+ }
+ ha:connection.54 {
+ li:conn {
+ /2/13/1/1
+ /2/27/2
+ }
+ }
+ ha:connection.55 {
+ li:conn {
+ /2/13/2/1
+ /2/24/2
+ }
+ }
+ ha:connection.60 {
+ li:conn {
+ /2/30/1
+ /2/13/3/1
+ }
+ }
+ ha:connection.61 {
+ li:conn {
+ /2/33/2/1
+ /2/30/1
+ }
+ }
+ ha:connection.62 {
+ li:conn {
/2/36/1
/2/33/1/1
}
}
- ha:connection.38 {
+ ha:connection.63 {
li:conn {
/2/36/1
/2/35/1/1
@@ -521,8 +525,6 @@
}
}
ha:attrib {
- drawing_min_height=200000
- drawing_min_width=287000
maintainer=