From 581131f1e01de55efb13d78a2ad53101769b39f7 Mon Sep 17 00:00:00 2001
From: Brendan Haines <brendan.haines@gmail.com>
Date: Mon, 7 Jul 2025 20:04:16 -0600
Subject: [PATCH] document and rearrange some stuff

---
 charon_vna/vna.py | 43 ++++++++++++++++++++-----------------------
 1 file changed, 20 insertions(+), 23 deletions(-)

diff --git a/charon_vna/vna.py b/charon_vna/vna.py
index 0f59ce9..253aa83 100644
--- a/charon_vna/vna.py
+++ b/charon_vna/vna.py
@@ -128,7 +128,7 @@ class Charon:
         self.sdr.rx_hardwaregain_chan1 = 10
         self.sdr.tx_hardwaregain_chan0 = -10
 
-        # # switch control
+        # switch control
         ctx = iio.Context(uri)
         self.ctrl = ctx.find_device("ad9361-phy")
         # raw ad9361 register accesss:
@@ -136,10 +136,13 @@ class Charon:
         # https://www.analog.com/media/cn/technical-documentation/user-guides/ad9364_register_map_reference_manual_ug-672.pdf  # noqa: E501
         self.ctrl.reg_write(AD9361Register.EXTERNAL_LNA_CONTROL, 0x90)  # bit 7: AuxDAC Manual, bit 4: GPO Manual
         self.ctrl.reg_write(AD9361Register.AUXDAC_ENABLE_CONTROL, 0x3F)
+
+        # initialize switch control outputs
         self._set_gpo(0b0000)
         self._set_dac_code(value=0, channel=1)
         self._set_dac_code(value=0, channel=2)
 
+        # set default switch state
         self.set_switches(a=0, b=0)
 
     def get_config(self) -> Dict[str, Any]:
@@ -170,20 +173,15 @@ class Charon:
     def _set_gpo(self, value: int) -> None:
         self.ctrl.reg_write(AD9361Register.GPO_FORCE_AND_INIT, (value & 0x0F) << 4)  # bits 7-4: GPO3-0
 
-    def _set_dac_voltage(self, voltage: float, channel: Literal[1, 2]):
-        raise NotImplementedError()
+    def _get_dac_code(self, channel: Literal[1, 2]) -> Tuple[float, AD9361DacVref, AD9361DacStepFactor]:
+        word = self.ctrl.reg_read(AD9361Register.__getitem__(f"AUXDAC{channel}_WORD"))
+        config = self.ctrl.reg_read(AD9361Register.__getitem__(f"AUXDAC{channel}_CONFIG"))
 
-    def set_switches(self, a: int, b: int, excitation: int | None = None):
-        if excitation is None:
-            excitation = a
+        value = (word << 2) + (config & 0x3)
+        vref = AD9361DacVref((config >> 2) & 0x3)
+        step_factor = AD9361DacStepFactor((config >> 4) & 0x1)
 
-        val = 0
-
-        val |= int(bool(excitation)) << 0  # exc = GPO0
-        val |= int(bool(a)) << 2  # a = GPO2
-        val |= int(bool(b)) << 1  # b = GPO1
-
-        self._set_gpo(val)
+        return (value, vref, step_factor)
 
     def _set_dac_code(
         self,
@@ -217,18 +215,17 @@ class Charon:
             (value & 0x3) | (vref.value << 2) | (step_factor << 4),
         )
 
-    def _get_dac_code(self, channel: Literal[1, 2]) -> Tuple[float, AD9361DacVref, AD9361DacStepFactor]:
-        word = self.ctrl.reg_read(AD9361Register.__getitem__(f"AUXDAC{channel}_WORD"))
-        config = self.ctrl.reg_read(AD9361Register.__getitem__(f"AUXDAC{channel}_CONFIG"))
+    def set_switches(self, b: int, a: int, excitation: int | None = None):
+        if excitation is None:
+            excitation = a
 
-        value = (word << 2) + (config & 0x3)
-        vref = AD9361DacVref((config >> 2) & 0x3)
-        step_factor = AD9361DacStepFactor((config >> 4) & 0x1)
+        val = 0
 
-        return (value, vref, step_factor)
+        val |= int(bool(excitation)) << 0  # exc = GPO0
+        val |= int(bool(a)) << 2  # a = GPO2
+        val |= int(bool(b)) << 1  # b = GPO1
 
-    def _get_dac_voltage(self) -> float:
-        raise NotImplementedError()
+        self._set_gpo(val)
 
     def set_output_power(self, power: float):
         pout = xr.DataArray(
@@ -320,7 +317,7 @@ class Charon:
             s.loc[dict(frequency=frequency)] = self.get_b_over_a(frequency=frequency)
         return s
 
-    def vna_capture(self, frequency: npt.ArrayLike, callback: Callable[int, int] | None):
+    def vna_capture(self, frequency: npt.ArrayLike, callback: Callable[int, int] | None = None):
         s = xr.DataArray(
             np.empty(len(frequency), dtype=np.complex128),
             dims=["frequency"],