mcp4018: Add SET_DIGIPOT command to mcp4018 implementation (#5737)

Added a SET_DIGIPOT command to the mcp4018 implementation.
Previously the mcp4018 was read only, and set at the time of
configuration.  This allows you to change the value during a
print, which is needed for some older printers that need to
lower the stepper current during preheating.

Signed-off-by: Jake Bordens <jake@allaboutjake.com>

config/sample-macros.cfg

@@ -261,3 +261,50 @@ gcode:
   {% if 'U' in params %}
     EXCLUDE_OBJECT RESET=1 NAME={params.U}
   {% endif %}
+
+######################################################################
+# G130: Set digital potentiometer value
+######################################################################
+
+# The macro below uses the MCP4018 SET_DIGIPOT command to implement
+# a `G130` as used on classic Mightyboard-based printers such as
+# The Makerbot Replicator 2/2X.
+#
+# The `G130` command can be used to lower the stepper current
+# during preheating and raise the current again prior to starting
+# the print.  This is necessary for printers with smaller power
+# supplies that needed all the power to heat the bed.
+#
+# This macro requires one or more [mcp4018] configuration sections:
+# (x_axis_pot, y_axis_pot, z_axis_pot, a_axis_pot, b_axis_pot)
+#
+# Example: G130 X20 Y20 Z20 A20 B20 ; Lower stepper Vrefs while heating
+
+[gcode_macro G130]
+gcode:
+  M400
+  {% if ('X' in params) and ('mcp4018 x_axis_pot' in printer.configfile.config) %}
+    {% set x_value = params['X']|float %}
+    {% set x_axis_pot_scale = printer.configfile.config["mcp4018 x_axis_pot"].scale|float %}
+    SET_DIGIPOT DIGIPOT=x_axis_pot WIPER={ x_axis_pot_scale * (x_value / 127.0)}
+  {% endif %}
+  {% if ('Y' in params) and ('mcp4018 y_axis_pot' in printer.configfile.config) %}
+    {% set y_value = params['Y']|float %}
+    {% set y_axis_pot_scale = printer.configfile.config["mcp4018 y_axis_pot"].scale|float %}
+    SET_DIGIPOT DIGIPOT=y_axis_pot WIPER={ y_axis_pot_scale * (y_value / 127.0)}
+  {% endif %}
+  {% if ('Z' in params) and ('mcp4018 z_axis_pot' in printer.configfile.config) %}
+    {% set z_value = params['Z']|float %}
+    {% set z_axis_pot_scale = printer.configfile.config["mcp4018 z_axis_pot"].scale|float %}
+    SET_DIGIPOT DIGIPOT=z_axis_pot WIPER={ z_axis_pot_scale * (z_value / 127.0)}
+  {% endif %}
+  {% if ('A' in params) and ('mcp4018 a_axis_pot' in printer.configfile.config) %}
+    {% set a_value = params['A']|float %}
+    {% set a_axis_pot_scale = printer.configfile.config["mcp4018 a_axis_pot"].scale|float %}
+    SET_DIGIPOT DIGIPOT=a_axis_pot WIPER={ a_axis_pot_scale * (a_value / 127.0)}
+  {% endif %}
+  {% if ('B' in params) and ('mcp4018 b_axis_pot' in printer.configfile.config) %}
+    {% set b_value = params['B']|float %}
+    {% set b_axis_pot_scale = printer.configfile.config["mcp4018 b_axis_pot"].scale|float %}
+    SET_DIGIPOT DIGIPOT=b_axis_pot WIPER={ b_axis_pot_scale * (b_value / 127.0)}
+  {% endif %}

docs/G-Codes.md

@@ -746,6 +746,20 @@ scheduled to run after the stepper move completes, however if a manual
 stepper move uses SYNC=0 then future G-Code movement commands may run
 in parallel with the stepper movement.
 
+### [mcp4018]
+
+The following command is available when a
+[mcp4018 config section](Config_Reference.md#mcp4018) is
+enabled.
+
+#### SET_DIGIPOT
+
+`SET_DIGIPOT DIGIPOT=config_name WIPER=<value>`: This command will
+change the current value of the digipot.  This value should typically
+be between 0.0 and 1.0, unless a 'scale' is defined in the config.
+When 'scale' is defined, then this value should be  between 0.0 and
+'scale'.
+
 ### [led]
 
 The following command is available when any of the

klippy/extras/mcp4018.py

@@ -68,17 +68,30 @@ class SoftwareI2C:
 
 class mcp4018:
     def __init__(self, config):
+        self.printer = config.get_printer()
         self.i2c = SoftwareI2C(config, 0x2f)
         self.scale = config.getfloat('scale', 1., above=0.)
         self.start_value = config.getfloat('wiper',
                                            minval=0., maxval=self.scale)
         config.get_printer().register_event_handler("klippy:connect",
                                                     self.handle_connect)
+        # Register commands
+        self.name = config.get_name().split()[1]
+        gcode = self.printer.lookup_object('gcode')
+        gcode.register_mux_command("SET_DIGIPOT", "DIGIPOT", self.name,
+                                   self.cmd_SET_DIGIPOT,
+                                   desc=self.cmd_SET_DIGIPOT_help)
     def handle_connect(self):
         self.set_dac(self.start_value)
     def set_dac(self, value):
         val = int(value * 127. / self.scale + .5)
         self.i2c.i2c_write([val])
-
+    cmd_SET_DIGIPOT_help = "Set digipot value"
+    def cmd_SET_DIGIPOT(self, gcmd):
+        wiper = gcmd.get_float('WIPER', minval=0., maxval=self.scale)
+        if wiper is not None:
+            self.set_dac(wiper)
+            gcmd.respond_info("New value for DIGIPOT = %s, wiper = %.2f"
+                               % (self.name, wiper))
 def load_config_prefix(config):
     return mcp4018(config)