diff --git a/charon_vna/vna.py b/charon_vna/vna.py
index d2d68f0..97d6415 100644
--- a/charon_vna/vna.py
+++ b/charon_vna/vna.py
@@ -66,6 +66,20 @@ class AD9361Register(IntEnum):
     AUXDAC2_TX_DELAY = 0x033
 
 
+@unique
+class AD9361DacVref(IntEnum):
+    VREF_1V0 = 0b00
+    VREF_1V5 = 0b01
+    VREF_2V0 = 0b10
+    VREF_2V5 = 0b11
+
+
+@unique
+class AD9361DacStepFactor(IntEnum):
+    FACTOR_2 = 0b0
+    FACTOR_1 = 0b1
+
+
 class Charon:
     FREQUENCY_OFFSET = 1e6
 
@@ -122,8 +136,8 @@ class Charon:
         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)
         self._set_gpo(0b0000)
-        self._set_dac(value=0, channel=1)
-        self._set_dac(value=0, channel=2)
+        self._set_dac_code(value=0, channel=1)
+        self._set_dac_code(value=0, channel=2)
 
     def get_config(self) -> Dict[str, Any]:
         config = dict()
@@ -153,24 +167,24 @@ 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(self, value: int, channel: Literal[1, 2]):
+    def _set_dac_voltage(self, voltage: float, channel: Literal[1, 2]):
+        raise NotImplementedError()
+
+    def _set_dac_code(
+        self,
+        value: int,
+        channel: Literal[1, 2],
+        vref: AD9361DacVref = AD9361DacVref.VREF_1V0,
+        step_factor: AD9361DacStepFactor = AD9361DacStepFactor.FACTOR_2,
+    ) -> None:
         if channel not in [1, 2]:
             raise ValueError(f"Invalid channel {channel}. Must be 1 or 2")
 
         if value > 0x3FF or value < 0:
             raise ValueError("Invalid value for 10 bit DAC. Must be between 0 and 0x3FF (inclusive)")
 
-        @unique
-        class Vref(IntEnum):
-            VREF_1V0 = 0b00
-            VREF_1V5 = 0b01
-            VREF_2V0 = 0b10
-            VREF_2V5 = 0b11
-
-        @unique
-        class StepFactor(IntEnum):
-            FACTOR_2 = 0b0
-            FACTOR_1 = 0b1
+        vref = AD9361DacVref(vref)
+        step_factor = AD9361DacStepFactor(step_factor)
 
         # https://www.analog.com/media/cn/technical-documentation/user-guides/ad9364_register_map_reference_manual_ug-672.pdf
         # page 13
@@ -185,9 +199,22 @@ class Charon:
         )
         self.ctrl.reg_write(
             AD9361Register.__getitem__(f"AUXDAC{channel}_CONFIG"),
-            (value & 0x3) | (Vref.VREF_1V0.value << 2) | (StepFactor.FACTOR_2 << 4),
+            (value & 0x3) | (vref.value << 2) | (step_factor << 4),
         )
 
+    def _get_dac_code(self, channel: int) -> 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"))
+
+        value = (word << 2) + (config & 0x3)
+        vref = AD9361DacVref((config >> 2) & 0x3)
+        step_factor = AD9361DacStepFactor((config >> 4) & 0x1)
+
+        return (value, vref, step_factor)
+
+    def _get_dac_voltage(self) -> float:
+        raise NotImplementedError()
+
     def set_output_power(self, power: float):
         pout = xr.DataArray(
             [-15, -10, -5, 0, 5],
@@ -288,6 +315,7 @@ class Charon:
         )
         for ff, freq in enumerate(s.frequency.data):
             if callback is not None:
+                # report progress during sweep
                 callback(ff, len(s.frequency))
             self.set_output(frequency=freq, power=-5)
             self.sdr.rx_destroy_buffer()
@@ -299,7 +327,9 @@ class Charon:
             self.sdr.rx_hardwaregain_chan1 = 40
             rx = self.sdr.rx()
             s.loc[dict(frequency=freq)] = np.mean(rx[1] / rx[0])
+
         if callback is not None:
+            # mark capture as complete
             callback(len(s.frequency), len(s.frequency))
 
         return s