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##
## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2019 Mickael Bosch <mickael.bosch@linux.com>
##
## 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/>.
##
import sigrokdecode as srd
NUM_OUTPUT_CHANNELS = 8
# TODO: Other I²C functions: general call / reset address, device ID address.
def logic_channels(num_channels, samplerate):
l = []
for i in range(num_channels):
l.append(tuple(['p%d' % i, 'P%d' % i]))
return tuple(l)
class Decoder(srd.Decoder):
api_version = 3
id = 'pca9571'
name = 'PCA9571'
longname = 'NXP PCA9571'
desc = 'NXP PCA9571 8-bit I²C output expander.'
license = 'gplv2+'
inputs = ['i2c']
outputs = []
tags = ['Embedded/industrial', 'IC']
annotations = (
('register', 'Register type'),
('value', 'Register value'),
('warning', 'Warning'),
)
logic_output_channels = logic_channels(NUM_OUTPUT_CHANNELS)
annotation_rows = (
('regs', 'Registers', (0, 1)),
('warnings', 'Warnings', (2,)),
)
def __init__(self):
self.reset()
def reset(self):
self.state = 'IDLE'
self.ss_logic = -1
self.last_write = 0xFF # Chip port default state is high.
def start(self):
self.out_ann = self.register(srd.OUTPUT_ANN)
self.out_logic = self.register(srd.OUTPUT_LOGIC)
def putx(self, data):
self.put(self.ss, self.es, self.out_ann, data)
def putl(self, data):
self.put(self.ss_logic, self.ss_logic, self.out_logic, data)
def handle_io(self, b):
if self.state == 'READ DATA':
operation = ['Outputs read', 'R']
if b != self.last_write:
self.putx([2, ['Warning: read value and last write value '
'(%02X) are different' % self.last_write]])
else:
operation = ['Outputs set', 'W']
self.last_write = b
self.putx([1, [operation[0] + ': %02X' % b,
operation[1] + ': %02X' % b]])
self.ss_logic = self.ss
for i in range(NUM_OUTPUT_CHANNELS):
bit = (b & (1 << i)) != 0
self.putl([i, bytes([bit])])
def check_correct_chip(self, addr):
if addr != 0x25:
self.putx([2, ['Warning: I²C slave 0x%02X not a PCA9571 '
'compatible chip.' % addr]])
return False
return True
def decode(self, ss, es, data):
cmd, databyte = data
self.ss, self.es = ss, es
# State machine.
if cmd in ('ACK', 'BITS'): # Discard 'ACK' and 'BITS'.
pass
elif cmd in ('START', 'START REPEAT'): # Start a communication.
self.state = 'GET SLAVE ADDR'
elif cmd in ('NACK', 'STOP'): # Reset the state machine.
self.state = 'IDLE'
elif cmd in ('ADDRESS READ', 'ADDRESS WRITE'):
if ((self.state == 'GET SLAVE ADDR') and
self.check_correct_chip(databyte)):
if cmd == 'ADDRESS READ':
self.state = 'READ DATA'
else:
self.state = 'WRITE DATA'
else:
self.state = 'IDLE'
elif cmd in ('DATA READ', 'DATA WRITE'):
if self.state in ('READ DATA', 'WRITE DATA'):
self.handle_io(databyte)
else:
self.state = 'IDLE'
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