query_adc: Add a new module to help query and debug analog pins

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

klippy/extras/query_adc.py

@@ -0,0 +1,36 @@
+# Utility for querying the current state of adc pins
+#
+# Copyright (C) 2019  Kevin O'Connor <kevin@koconnor.net>
+#
+# This file may be distributed under the terms of the GNU GPLv3 license.
+
+class QueryADC:
+    def __init__(self, config):
+        self.printer = config.get_printer()
+        self.adc = {}
+        gcode = self.printer.lookup_object('gcode')
+        gcode.register_command("QUERY_ADC", self.cmd_QUERY_ADC,
+                               desc=self.cmd_QUERY_ADC_help)
+    def register_adc(self, name, mcu_adc):
+        self.adc[name] = mcu_adc
+    cmd_QUERY_ADC_help = "Report the last value of an analog pin"
+    def cmd_QUERY_ADC(self, params):
+        gcode = self.printer.lookup_object('gcode')
+        name = gcode.get_str('NAME', params, None)
+        if name not in self.adc:
+            objs = ['"%s"' % (n,) for n in sorted(self.adc.keys())]
+            msg = "Available ADC objects: %s" % (', '.join(objs),)
+            gcode.respond_info(msg)
+            return
+        value, timestamp = self.adc[name].get_last_value()
+        msg = 'ADC object "%s" has value %.6f (timestamp %.3f)' % (
+            name, value, timestamp)
+        pullup = gcode.get_float('PULLUP', params, None, above=0.)
+        if pullup is not None:
+            v = max(.00001, min(.99999, value))
+            r = pullup * v / (1.0 - v)
+            msg += "\n resistance %.3f (with %.0f pullup)" % (r, pullup)
+        gcode.respond_info(msg)
+
+def load_config(config):
+    return QueryADC(config)