implement getTrace and channel preamble parser

1 files changed, 69 insertions, 0 deletions

diff --git a/qolab/hardware/scope/sds800xhd.py b/qolab/hardware/scope/sds800xhd.py
index 436254f..fabf43e 100644
--- a/qolab/hardware/scope/sds800xhd.py
+++ b/qolab/hardware/scope/sds800xhd.py
@@ -167,6 +167,75 @@ class SDS800XHD(SDS1104X):
         trRaw.config["tags"]["rawChanConfig"] = rawChanCfg
         return trRaw
 
+    def getParsedPreamble(self):
+        """
+        Parse preamble generated by the scope.
+        It has a lot of information, number of points, scale, bits resolution, etc.
+
+        Note: preamble is channel specific! The prior code must set desired channel
+        with self.write(":WAVeform:SOURce C{chNum}")
+        """
+        preamble = {}
+        qstr = ":WAVeform:PREamble?"
+        if self.resource.interface_type == InterfaceType.usb:
+            # Setting chunk size to 496 bytes, it seems that SDS sends data
+            # in 512 bytes chunks via USB.
+            # Which is 8 packets of 64 bytes, but each packet takes 2 bytes for a header.
+            # Thus useful payload is 512-8*2 = 496
+            # see https://patchwork.ozlabs.org/project/qemu-devel/patch/20200317095049.28486-4-kraxel@redhat.com/
+            # Setting chunk_size for a large number has *catastrophic* results
+            # on data transfer rate, since we wait for more data
+            # which is not going to come until timeout expires
+            resp_bin = self.query_binary_values(
+                qstr,
+                datatype="c",
+                header_fmt="ieee",
+                container=np.array,
+                chunk_size=496,
+            )
+        else:
+            resp_bin = self.query_binary_values(
+                qstr, datatype="c", header_fmt="ieee", container=np.array
+            )
+        preamble["Npoints"] = resp_bin[116:120].view(np.int32).item()
+        preamble["firstPoint"] = resp_bin[132:136].view(np.int32).item()
+        preamble["sparsing"] = resp_bin[136:140].view(np.int32).item()
+        preamble["voltsPerDiv"] = resp_bin[156:160].view(np.float32).item()
+        preamble["verticalOffset"] = resp_bin[160:164].view(np.float32).item()
+        preamble["codePerDiv"] = resp_bin[164:168].view(np.float32).item()
+        preamble["adcBit"] = resp_bin[172:174].view(np.int16).item()
+        preamble["samplingTime"] = resp_bin[176:180].view(np.float32).item()
+        preamble["trigDelay"] = (
+            -resp_bin[180:188].view(np.float64).item()
+        )  # manual is wrong, it claims that this int64
+
+        return preamble, resp_bin
+
+    def getWaveform(
+        self, chNum, availableNpnts=None, maxRequiredPoints=None, decimate=True
+    ):
+        """
+        For decimate use see ``getRawWaveform``.
+
+        In short decimate=True is slower but more precise.
+        """
+        trRaw = self.getRawWaveform(
+            chNum,
+            availableNpnts=availableNpnts,
+            maxRequiredPoints=maxRequiredPoints,
+            decimate=decimate,
+        )
+        preamble = self.getParsedPreamble()
+        VoltageOffset = preamble["verticalOffset"]
+        VoltsPerDiv = preamble["voltsPerDiv"]
+        tr = trRaw
+        tr.values = trRaw.values * VoltsPerDiv / preamble["codePerDiv"] - VoltageOffset
+        tr.config["unit"] = "Volt"
+        tr.config["tags"]["VoltageOffset"] = VoltageOffset
+        tr.config["tags"]["VoltsPerDiv"] = VoltsPerDiv
+        tr.config["tags"]["Preamble"] = preamble
+        return tr
+
 
 if __name__ == "__main__":
     import pyvisa