## ## This file is part of the sigrok project. ## ## Copyright (C) 2011 Gareth McMullin ## Copyright (C) 2012 Uwe Hermann ## ## 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 # Chip-select options ACTIVE_LOW = 0 ACTIVE_HIGH = 1 # Clock polarity options CPOL_0 = 0 # Clock is low when inactive CPOL_1 = 1 # Clock is high when inactive # Clock phase options CPHA_0 = 0 # Data is valid on the leading clock edge CPHA_1 = 1 # Data is valid on the trailing clock edge # Bit order options MSB_FIRST = 0 LSB_FIRST = 1 spi_mode = { (0, 0): 0, # Mode 0 (0, 1): 1, # Mode 1 (1, 0): 2, # Mode 2 (1, 1): 3, # Mode 3 } # Annotation formats ANN_HEX = 0 class Decoder(srd.Decoder): api_version = 1 id = 'spi' name = 'SPI' longname = 'Serial Peripheral Interface' desc = '...desc...' longdesc = '...longdesc...' license = 'gplv2+' inputs = ['logic'] outputs = ['spi'] probes = [ {'id': 'mosi', 'name': 'MOSI', 'desc': 'SPI MOSI line (Master out, slave in)'}, {'id': 'miso', 'name': 'MISO', 'desc': 'SPI MISO line (Master in, slave out)'}, {'id': 'sck', 'name': 'CLK', 'desc': 'SPI clock line'}, {'id': 'cs', 'name': 'CS#', 'desc': 'SPI CS (chip select) line'}, ] options = { 'cs_polarity': ['CS# polarity', ACTIVE_LOW], 'cpol': ['Clock polarity', CPOL_0], 'cpha': ['Clock phase', CPHA_0], 'bitorder': ['Bit order within the SPI data', MSB_FIRST], 'wordsize': ['Word size of SPI data', 8], # 1-64? } annotations = [ ['Hex', 'SPI data bytes in hex format'], ] def __init__(self): self.oldsck = 1 self.bitcount = 0 self.mosidata = 0 self.misodata = 0 self.bytesreceived = 0 self.samplenum = -1 self.cs_was_deasserted_during_data_word = 0 # Set protocol decoder option defaults. self.cs_polarity = Decoder.options['cs_polarity'][1] self.cpol = Decoder.options['cpol'][1] self.cpha = Decoder.options['cpha'][1] self.bitorder = Decoder.options['bitorder'][1] self.wordsize = Decoder.options['wordsize'][1] def start(self, metadata): self.out_proto = self.add(srd.OUTPUT_PROTO, 'spi') self.out_ann = self.add(srd.OUTPUT_ANN, 'spi') def report(self): return 'SPI: %d bytes received' % self.bytesreceived def decode(self, ss, es, data): # HACK! At the moment the number of probes is not handled correctly. # E.g. if an input file (-i foo.sr) has more than two probes enabled. # for (samplenum, (mosi, sck, x, y, z, a)) in data: # for (samplenum, (cs, miso, sck, mosi, wp, hold)) in data: for (samplenum, (cs, miso, sck, mosi, wp, hold)) in data: self.samplenum += 1 # FIXME # Ignore sample if the clock pin hasn't changed. if sck == self.oldsck: continue self.oldsck = sck # Sample data on rising/falling clock edge (depends on mode). mode = spi_mode[self.cpol, self.cpha] if mode == 0 and sck == 0: # Sample on rising clock edge continue elif mode == 1 and sck == 1: # Sample on falling clock edge continue elif mode == 2 and sck == 1: # Sample on falling clock edge continue elif mode == 3 and sck == 0: # Sample on rising clock edge continue # If this is the first bit, save its sample number. if self.bitcount == 0: self.start_sample = samplenum deasserted = cs if (self.cs_polarity == ACTIVE_LOW) else not c if deasserted: self.cs_was_deasserted_during_data_word = 1 # Receive MOSI bit into our shift register. if self.bitorder == MSB_FIRST: self.mosidata |= mosi << (self.wordsize - 1 - self.bitcount) else: self.mosidata |= mosi << self.bitcount # Receive MISO bit into our shift register. if self.bitorder == MSB_FIRST: self.misodata |= miso << (self.wordsize - 1 - self.bitcount) else: self.misodata |= miso << self.bitcount self.bitcount += 1 # Continue to receive if not a byte yet. if self.bitcount != self.wordsize: continue self.put(self.start_sample, self.samplenum, self.out_proto, ['data', self.mosidata, self.misodata]) self.put(self.start_sample, self.samplenum, self.out_ann, [ANN_HEX, ['MOSI: 0x%02x, MISO: 0x%02x' % (self.mosidata, self.misodata)]]) if self.cs_was_deasserted_during_data_word: self.put(self.start_sample, self.samplenum, self.out_ann, [ANN_HEX, ['WARNING: CS# was deasserted during this ' 'SPI data byte!']]) # Reset decoder state. self.mosidata = 0 self.misodata = 0 self.bitcount = 0 # Keep stats for summary. self.bytesreceived += 1