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##
## This file is part of the sigrok project.
##
## Copyright (C) 2011 Gareth McMullin <gareth@blacksphere.co.nz>
##
## 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 sigrok
class Sample():
def __init__(self, data):
self.data = data
def probe(self, probe):
s = ord(self.data[probe / 8]) & (1 << (probe % 8))
return True if s else False
def sampleiter(data, unitsize):
for i in range(0, len(data), unitsize):
yield(Sample(data[i:i+unitsize]))
class Decoder(sigrok.Decoder):
id = 'spi'
name = 'SPI'
desc = '...desc...'
longname = 'Serial Peripheral Interface (SPI) bus'
longdesc = '...longdesc...'
author = 'Gareth McMullin'
email = 'gareth@blacksphere.co.nz'
license = 'gplv2+'
inputs = ['logic']
outputs = ['spi']
# Probe names with a set of defaults
probes = {'sdata':0, 'sck':1}
options = {}
def __init__(self):
self.probes = Decoder.probes.copy()
self.oldsck = True
self.rxcount = 0
self.rxdata = 0
self.bytesreceived = 0
def start(self, metadata):
self.unitsize = metadata['unitsize']
def report(self):
return 'SPI: %d bytes received' % self.bytesreceived
def decode(self, data):
# We should accept a list of samples and iterate...
for sample in sampleiter(data['data'], self.unitsize):
sck = sample.probe(self.probes['sck'])
# Sample SDATA on rising SCK
if sck == self.oldsck:
continue
self.oldsck = sck
if not sck:
continue
# If this is first bit, save timestamp
if self.rxcount == 0:
self.time = data['time']
# Receive bit into our shift register
sdata = sample.probe(self.probes['sdata'])
if sdata:
self.rxdata |= 1 << (7 - self.rxcount)
self.rxcount += 1
# Continue to receive if not a byte yet
if self.rxcount != 8:
continue
# Received a byte, pass up to sigrok
outdata = {'time':self.time,
'duration':data['time'] + data['duration'] - self.time,
'data':self.rxdata,
'display':('%02X' % self.rxdata),
'type':'spi',
}
self.put(outdata)
# Reset decoder state
self.rxdata = 0
self.rxcount = 0
# Keep stats for summary
self.bytesreceived += 1
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