Add a decoder for stepper motor direction/speed signals.

diff --git a/decoders/stepper_motor/__init__.py b/decoders/stepper_motor/__init__.py
new file mode 100644 (file)
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+++ b/decoders/stepper_motor/__init__.py
@@ -0,0 +1,26 @@
+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2015 Petteri Aimonen <jpa@sigrok.mail.kapsi.fi>
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 2 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program; if not, write to the Free Software
+## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+##
+
+'''
+This PD decodes the stepper motor controller signals (step / dir) and
+shows the step speed and absolute position of the stepper motor.
+'''
+
+from .pd import Decoder

diff --git a/decoders/stepper_motor/pd.py b/decoders/stepper_motor/pd.py
new file mode 100644 (file)
index 0000000..b3bb5bc
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+++ b/decoders/stepper_motor/pd.py
@@ -0,0 +1,97 @@
+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2015 Petteri Aimonen <jpa@sigrok.mail.kapsi.fi>
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 2 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program; if not, write to the Free Software
+## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+##
+
+import sigrokdecode as srd
+
+class SamplerateError(Exception):
+    pass
+
+class Decoder(srd.Decoder):
+    api_version = 2
+    id = 'stepper_motor'
+    name = 'Stepper motor'
+    longname = 'Stepper motor position / speed'
+    desc = 'Calculate absolute position and movement speed from step/dir signals.'
+    license = 'gplv2+'
+    inputs = ['logic']
+    outputs = ['stepper_motor']
+    channels = (
+        {'id': 'step', 'name': 'Step', 'desc': 'Step pulse'},
+        {'id': 'dir', 'name': 'Direction', 'desc': 'Direction select'},
+    )
+    options = (
+        {'id': 'unit', 'desc': 'Unit', 'default': 'steps',
+         'values': ('steps', 'mm')},
+        {'id': 'steps_per_mm', 'desc': 'Steps per mm', 'default': 100.0},
+    )
+    annotations = (
+        ('speed', 'Speed'),
+        ('position', 'Position')
+    )
+    annotation_rows = (
+        ('speed', 'Speed', (0,)),
+        ('position', 'Position', (1,)),
+    )
+
+    def __init__(self, **kwargs):
+        self.oldstep = None
+        self.prev_step_ss = None
+        self.pos = 0
+        self.prev_speed = None
+        self.prev_pos = None
+
+    def start(self):
+        self.out_ann = self.register(srd.OUTPUT_ANN)
+
+        if self.options['unit'] == 'steps':
+            self.scale = 1
+            self.format = '%0.0f'
+            self.unit = 'steps'
+        else:
+            self.scale = self.options['steps_per_mm']
+            self.format = '%0.2f'
+            self.unit = 'mm'
+
+    def step(self, ss, direction):
+        if self.prev_step_ss is not None:
+            delta = ss - self.prev_step_ss
+            speed = self.samplerate / delta / self.scale
+            speed_txt = self.format % speed
+            pos_txt = self.format % (self.pos / self.scale)
+            self.put(self.prev_step_ss, ss, self.out_ann,
+                [0, [speed_txt + ' ' + self.unit + '/s', speed_txt]])
+            self.put(self.prev_step_ss, ss, self.out_ann,
+                [1, [pos_txt + ' ' + self.unit, pos_txt]])
+
+        self.pos += (1 if direction else -1)
+        self.prev_step_ss = ss
+
+    def metadata(self, key, value):
+        if key == srd.SRD_CONF_SAMPLERATE:
+            self.samplerate = value
+
+    def decode(self, ss, es, data):
+        if not self.samplerate:
+            raise SamplerateError('Cannot decode without samplerate.')
+
+        for (self.samplenum, (step, direction)) in data:
+            if step == 1 and self.oldstep == 0:
+                self.step(self.samplenum, direction)
+            self.oldstep = step