From 4f36a1654ff6560c915a39e1f9999e0efc4a9680 Mon Sep 17 00:00:00 2001
From: Tanner Robison <Robison.tnr@gmail.com>
Date: Tue, 7 Jul 2026 20:48:28 -0700
Subject: SPICE model in the loop testing

---
 MIL_testing/integration_test.py | 14 +++++++++
 MIL_testing/ng_test1.cir        | 25 +++++++++++++++
 MIL_testing/spice_backend.py    | 70 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 109 insertions(+)
 create mode 100644 MIL_testing/integration_test.py
 create mode 100644 MIL_testing/ng_test1.cir
 create mode 100644 MIL_testing/spice_backend.py

(limited to 'MIL_testing')

diff --git a/MIL_testing/integration_test.py b/MIL_testing/integration_test.py
new file mode 100644
index 0000000..7c8e2fa
--- /dev/null
+++ b/MIL_testing/integration_test.py
@@ -0,0 +1,14 @@
+import subprocess
+
+result = subprocess.run(
+    ["ngspice", "-b", "ng_test1.cir"],
+    capture_output=True,
+    text=True
+)
+
+print("Return code:", result.returncode)
+print(result.stdout)
+
+if result.stderr:
+    print("Errors:")
+    print(result.stderr)
diff --git a/MIL_testing/ng_test1.cir b/MIL_testing/ng_test1.cir
new file mode 100644
index 0000000..892a284
--- /dev/null
+++ b/MIL_testing/ng_test1.cir
@@ -0,0 +1,25 @@
+* RC Charging Circuit
+
+V1 in 0 PULSE(0 5 1u 1u 1u 100m 200m)
+
+R1 in out 1k
+
+C1 out 0 1u
+
+.tran 10u 50m
+
+.control
+run
+
+set finalindex = $&{length(v(in)) - 1}
+
+let final_vin = v(in)[$finalindex]
+let final_vout = v(out)[$finalindex]
+let final_current = v1#branch[$finalindex]
+
+echo "----- final time analysis -----"
+print final_vin final_vout
+print final_current
+
+.endc
+.end
diff --git a/MIL_testing/spice_backend.py b/MIL_testing/spice_backend.py
new file mode 100644
index 0000000..674ae30
--- /dev/null
+++ b/MIL_testing/spice_backend.py
@@ -0,0 +1,70 @@
+import subprocess
+import re
+
+class SpiceBackend:
+    """This is what actually does all of the spice stuff"""
+    def __init__(self, device_file: str):
+        self.conductance = 0
+        self.voltage = 0
+        self.current = 0
+        self.time = 0
+
+    def simulate(self, voltage_signal: float, return_current: bool = False) -> float:
+        """runs the simulation for one time step"""
+        len_voltage_signal = 1
+        try:
+            len_voltage_signal = len(voltage_signal)
+        except:
+            voltage_signal = [voltage_signal]
+
+        if return_current:
+            current = np.zeros(len_voltage_signal)
+
+        for t in enumerate(len_voltage_signal):
+            result = self.run_spice(voltage_signal)
+
+            single_current = result.current
+            self.conductance = result.conductance
+
+            if return_current:
+                current[t] = single_current
+
+        if return_current:
+            return current
+
+
+    def set_conductance(self, conductance: float):
+        """Handled by spice now"""
+        """Could probably still add some safety checks just to be sure later"""
+        self.conductance = conductance
+
+    def run_spice(self, voltage: float) -> float:
+        """returns the current after given a voltage signal"""
+        #need to find a way to pass voltage signal to ngspice here
+        #also maybe a time series resolution??
+        result = subprocess.run(
+                ["ngspice" "-b" "spicefile.cir"],
+                capture_output=True,
+                text=True
+        )
+        if result.returncode != 0:
+            raise RuntimeError(result.stderr)
+
+        # parse current into float variable
+        output = result.stdout
+        #is there a better (less rigid) way of grabbing the output
+        current_match = re.search("final_current = ([-\deE.+]+)", output)
+        if current_match is None:
+            raise RuntimeError("Could not find current in ngspice output")
+
+        current = float(current_match.group(1))
+
+        if abs(voltage) > 1e-12:
+            conductance = current / voltage
+        else:
+            conductance = self.conductance
+
+        return {
+                "current": current,
+                "conductance": conductance,
+        }
-- 
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