pins: Add support for pull down resistors

Add initial support for selecting pull down resistors (for
micro-controllers that support it).

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

1 files changed, 4 insertions, 2 deletions

diff --git a/klippy/pins.py b/klippy/pins.py
index 47bd87b5..90679ad1 100644
--- a/klippy/pins.py
+++ b/klippy/pins.py
@@ -215,8 +215,10 @@ class PrinterPins:
                    share_type=None):
         desc = pin_desc.strip()
         pullup = invert = 0
-        if can_pullup and desc.startswith('^'):
+        if can_pullup and (desc.startswith('^') or desc.startswith('~')):
             pullup = 1
+            if desc.startswith('~'):
+                pullup = -1
             desc = desc[1:].strip()
         if can_invert and desc.startswith('!'):
             invert = 1
@@ -227,7 +229,7 @@ class PrinterPins:
             chip_name, pin = [s.strip() for s in desc.split(':', 1)]
         if chip_name not in self.chips:
             raise error("Unknown pin chip name '%s'" % (chip_name,))
-        if [c for c in '^!: ' if c in pin]:
+        if [c for c in '^~!: ' if c in pin]:
             format = ""
             if can_pullup:
                 format += "[^] "