Add 'Digital calipers' decoder from libsigrokdecode codebase

This commit is contained in:
Abdelhak Bougouffa 2021-02-02 10:18:11 +01:00
parent c8c3b30a0b
commit 48ec33c45c
2 changed files with 182 additions and 0 deletions

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##
## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2020 Tomas Mudrunka <harvie@github>
##
## 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, see <http://www.gnu.org/licenses/>.
##
'''
This decoder interprets the digital output of cheap generic calipers
(usually made in China), and shows the measured value in millimeters
or inches.
Notice that these devices often communicate on voltage levels below
3.3V and may require additional circuitry to capture the signal.
This decoder does not work for calipers using the Digimatic protocol
(eg. Mitutoyo and similar brands).
For more information see:
http://www.shumatech.com/support/chinese_scales.htm
https://www.instructables.com/id/Reading-Digital-Callipers-with-an-Arduino-USB/
'''
from .pd import Decoder

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##
## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2020 Tomas Mudrunka <harvie@github>
##
## Permission is hereby granted, free of charge, to any person obtaining a copy
## of this software and associated documentation files (the "Software"), to deal
## in the Software without restriction, including without limitation the rights
## to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
## copies of the Software, and to permit persons to whom the Software is
## furnished to do so, subject to the following conditions:
##
## The above copyright notice and this permission notice shall be included in all
## copies or substantial portions of the Software.
##
## THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
## IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
## FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
## AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
## LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
## OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
## SOFTWARE.
import sigrokdecode as srd
from common.srdhelper import bitpack
# Millimeters per inch.
mm_per_inch = 25.4
class Decoder(srd.Decoder):
api_version = 3
id = 'caliper'
name = 'Caliper'
longname = 'Digital calipers'
desc = 'Protocol of cheap generic digital calipers.'
license = 'mit'
inputs = ['logic']
outputs = []
channels = (
{'id': 'clk', 'name': 'CLK', 'desc': 'Serial clock line'},
{'id': 'data', 'name': 'DATA', 'desc': 'Serial data line'},
)
options = (
{'id': 'timeout_ms', 'desc': 'Packet timeout in ms, 0 to disable',
'default': 10},
{'id': 'unit', 'desc': 'Convert units', 'default': 'keep',
'values': ('keep', 'mm', 'inch')},
{'id': 'changes', 'desc': 'Changes only', 'default': 'no',
'values': ('no', 'yes')},
)
tags = ['Analog/digital', 'Sensor']
annotations = (
('measurement', 'Measurement'),
('warning', 'Warning'),
)
annotation_rows = (
('measurements', 'Measurements', (0,)),
('warnings', 'Warnings', (1,)),
)
def metadata(self, key, value):
if key == srd.SRD_CONF_SAMPLERATE:
self.samplerate = value
def __init__(self):
self.reset()
def reset(self):
self.ss, self.es = 0, 0
self.number_bits = []
self.flags_bits = []
def start(self):
self.out_ann = self.register(srd.OUTPUT_ANN)
def putg(self, ss, es, cls, data):
self.put(ss, es, self.out_ann, [cls, data])
def decode(self):
last_sent = None
timeout_ms = self.options['timeout_ms']
want_unit = self.options['unit']
show_all = self.options['changes'] == 'no'
wait_cond = [{0: 'r'}]
if timeout_ms:
snum_per_ms = self.samplerate / 1000
timeout_snum = timeout_ms * snum_per_ms
wait_cond.append({'skip': round(timeout_snum)})
while True:
# Sample data at the rising clock edge. Optionally timeout
# after inactivity for a user specified period. Present the
# number of unprocessed bits to the user for diagnostics.
clk, data = self.wait(wait_cond)
if timeout_ms and not self.matched[0]:
if self.number_bits or self.flags_bits:
count = len(self.number_bits) + len(self.flags_bits)
self.putg(self.ss, self.samplenum, 1, [
'timeout with {} bits in buffer'.format(count),
'timeout ({} bits)'.format(count),
'timeout',
])
self.reset()
continue
# Store position of first bit and last activity.
# Shift in measured number and flag bits.
if not self.ss:
self.ss = self.samplenum
self.es = self.samplenum
if len(self.number_bits) < 16:
self.number_bits.append(data)
continue
if len(self.flags_bits) < 8:
self.flags_bits.append(data)
if len(self.flags_bits) < 8:
continue
# Get raw values from received data bits. Run the number
# conversion, controlled by flags and/or user specs.
negative = bool(self.flags_bits[4])
is_inch = bool(self.flags_bits[7])
number = bitpack(self.number_bits)
if negative:
number = -number
if is_inch:
number /= 2000
if want_unit == 'mm':
number *= mm_per_inch
is_inch = False
else:
number /= 100
if want_unit == 'inch':
number = round(number / mm_per_inch, 4)
is_inch = True
unit = 'in' if is_inch else 'mm'
# Construct and emit an annotation.
if show_all or (number, unit) != last_sent:
self.putg(self.ss, self.es, 0, [
'{number}{unit}'.format(**locals()),
'{number}'.format(**locals()),
])
last_sent = (number, unit)
# Reset internal state for the start of the next packet.
self.reset()