mcp4018: Add initial support for the mcp4018 digipot

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

1 files changed, 25 insertions, 0 deletions

diff --git a/config/example-extras.cfg b/config/example-extras.cfg
index 14ea6391..5451eac5 100644
--- a/config/example-extras.cfg
+++ b/config/example-extras.cfg
@@ -778,6 +778,31 @@
 #   default is to not scale the 'channel_x' parameters.
 
 
+# Statically configured MCP4018 digipot connected via two gpio "bit
+# banging" pins (one may define any number of sections with an
+# "mcp4018" prefix).
+#[mcp4018 my_digipot]
+#scl_pin:
+#   The SCL "clock" pin. This parameter must be provided.
+#sda_pin:
+#   The SDA "data" pin. This parameter must be provided.
+#wiper:
+#   The value to statically set the given MCP4018 "wiper" to. This is
+#   typically set to a number between 0.0 and 1.0 with 1.0 being the
+#   highest resistance and 0.0 being the lowest resistance. However,
+#   the range may be changed with the 'scale' parameter (see
+#   below). This parameter must be provided.
+#scale:
+#   This parameter can be used to alter how the 'wiper' parameter is
+#   interpreted. If provided, then the 'wiper' parameter should be
+#   between 0.0 and 'scale'. This may be useful when the MCP4018 is
+#   used to set stepper voltage references. The 'scale' can be set to
+#   the equivalent stepper amperage if the MCP4018 is at its highest
+#   resistance, and then the 'wiper' parameter can be specified using
+#   the desired amperage value for the stepper. The default is to not
+#   scale the 'wiper' parameter.
+
+
 # Configure an SX1509 I2C to GPIO expander. Due to the delay incurred
 # by I2C communication you should NOT use SX1509 pins as stepper enable,
 # step or dir pins or any other pin that requires fast bit-banging. They