--- /dev/null
+##
+## This file is part of the sigrok project.
+##
+## Copyright (C) 2012 Uwe Hermann <uwe@hermann-uwe.de>
+##
+## 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
+##
+
+# National LM75 (and compatibles) temperature sensor protocol decoder
+
+# TODO: Better support for various LM75 compatible devices.
+
+import sigrokdecode as srd
+
+# LM75 only supports 9 bit resolution, compatible devices usually 9-12 bits.
+resolution = {
+ # CONFIG[6:5]: <resolution>
+ 0x00: 9,
+ 0x01: 10,
+ 0x02: 11,
+ 0x03: 12,
+}
+
+ft = {
+ # CONFIG[4:3]: <fault tolerance setting>
+ 0x00: 1,
+ 0x01: 2,
+ 0x02: 4,
+ 0x03: 6,
+}
+
+class Decoder(srd.Decoder):
+ api_version = 1
+ id = 'lm75'
+ name = 'LM75'
+ longname = 'National LM75'
+ desc = 'National LM75 (and compatibles) temperature sensor protocol.'
+ license = 'gplv2+'
+ inputs = ['i2c']
+ outputs = ['lm75']
+ probes = []
+ optional_probes = [
+ {'id': 'os', 'name': 'OS', 'desc': 'Overtemperature shutdown'},
+ {'id': 'a0', 'name': 'A0', 'desc': 'I2C slave address input 0'},
+ {'id': 'a1', 'name': 'A1', 'desc': 'I2C slave address input 1'},
+ {'id': 'a2', 'name': 'A2', 'desc': 'I2C slave address input 2'},
+ ]
+ options = {
+ 'sensor': ['Sensor type', 'lm75'],
+ 'resolution': ['Resolution', 9], # 9-12 bit, sensor/config dependent
+ }
+ annotations = [
+ ['Celsius', 'Temperature in degrees Celsius'],
+ ['Kelvin', 'Temperature in degrees Kelvin'],
+ ['Text (verbose)', 'Human-readable text (verbose)'],
+ ['Text', 'Human-readable text'],
+ ['Warnings', 'Human-readable warnings'],
+ ]
+
+ def __init__(self, **kwargs):
+ self.state = 'IDLE'
+ self.reg = 0x00 # Currently selected register
+ self.databytes = []
+ self.mintemp = 0
+ self.maxtemp = 0
+ self.avgtemp = 0
+
+ def start(self, metadata):
+ # self.out_proto = self.add(srd.OUTPUT_PROTO, 'lm75')
+ self.out_ann = self.add(srd.OUTPUT_ANN, 'lm75')
+
+ def report(self):
+ # TODO: Output min/max/avg temperature.
+ pass
+
+ def putx(self, data):
+ # Helper for annotations which span exactly one I2C packet.
+ self.put(self.ss, self.es, self.out_ann, data)
+
+ def putb(self, data):
+ # Helper for annotations which span a block of I2C packets.
+ self.put(self.block_start, self.block_end, self.out_ann, data)
+
+ def warn_upon_invalid_slave(self, addr):
+ # LM75 and compatible devices have a 7-bit I2C slave address where
+ # the 4 MSBs are fixed to 1001, and the 3 LSBs are configurable.
+ # Thus, valid slave addresses (1001xxx) range from 0x48 to 0x4f.
+ if addr not in range(0x48, 0x4f + 1):
+ s = 'Warning: I2C slave 0x%02x not an LM75 compatible sensor.'
+ self.putx([4, [s % addr]])
+
+ def output_temperature(self, s):
+ # TODO: Support for resolutions other than 9 bit.
+ before, after = self.databytes[0], (self.databytes[1] >> 7) * 5
+ celsius = float('%d.%d' % (before, after))
+ kelvin = celsius + 273.15
+ self.putb([0, ['%s: %.1f °C' % (s, celsius)]])
+ self.putb([1, ['%s: %.1f °K' % (s, kelvin)]])
+
+ # Keep some statistics. Can be output in report(), for example.
+ if celsius < self.mintemp:
+ self.mintemp = celsius
+ if celsius > self.maxtemp:
+ self.maxtemp = celsius
+ # TODO: avg. temp.
+
+ def handle_temperature_reg(self, b, s):
+ # Common helper for the temperature/T_HYST/T_OS registers.
+ if len(self.databytes) == 0:
+ self.block_start = self.ss
+ self.databytes.append(b)
+ return
+ self.databytes.append(b)
+ self.block_end = self.es
+ self.output_temperature(s)
+ self.databytes = []
+
+ def handle_reg_0x00(self, b):
+ # Temperature register (16bits, read-only).
+ self.handle_temperature_reg(b, 'Temperature')
+
+ def handle_reg_0x01(self, b):
+ # Configuration register (8 bits, read/write).
+ # TODO: Bit-exact annotation ranges.
+
+ sd = b & (1 << 0)
+ tmp = 'normal operation' if (sd == 0) else 'shutdown mode'
+ s = 'SD = %d: %s\n' % (sd, tmp)
+ s2 = 'SD = %s, ' % tmp
+
+ cmp_int = b & (1 << 1)
+ tmp = 'comparator' if (cmp_int == 0) else 'interrupt'
+ s += 'CMP/INT = %d: %s mode\n' % (cmp_int, tmp)
+ s2 += 'CMP/INT = %s, ' % tmp
+
+ pol = b & (1 << 2)
+ tmp = 'low' if (pol == 0) else 'high'
+ s += 'POL = %d: OS polarity is active-%s\n' % (pol, tmp)
+ s2 += 'POL = active-%s, ' % tmp
+
+ bits = (b & ((1 << 4) | (1 << 3))) >> 3
+ s += 'Fault tolerance setting: %d bit(s)\n' % ft[bits]
+ s2 += 'FT = %d' % ft[bits]
+
+ # Not supported by LM75, but by various compatible devices.
+ if self.options['sensor'] != 'lm75': # TODO
+ bits = (b & ((1 << 6) | (1 << 5))) >> 5
+ s += 'Resolution: %d bits\n' % resolution[bits]
+ s2 += ', resolution = %d' % resolution[bits]
+
+ self.putx([2, [s]])
+ self.putx([3, [s2]])
+
+ def handle_reg_0x02(self, b):
+ # T_HYST register (16 bits, read/write).
+ self.handle_temperature_reg(b, 'T_HYST trip temperature')
+
+ def handle_reg_0x03(self, b):
+ # T_OS register (16 bits, read/write).
+ self.handle_temperature_reg(b, 'T_OS trip temperature')
+
+ def handle_reg_write(self, b):
+ # TODO
+ self.putx([0, ['LM75 write: reg 0x%02x = 0x%02x' % (self.reg, b)]])
+
+ def decode(self, ss, es, data):
+ cmd, databyte = data
+
+ # Store the start/end samples of this I2C packet.
+ self.ss, self.es = ss, es
+
+ # State machine.
+ if self.state == 'IDLE':
+ # Wait for an I2C START condition.
+ if cmd != 'START':
+ return
+ self.state = 'GET SLAVE ADDR'
+ elif self.state == 'GET SLAVE ADDR':
+ # Wait for an address read/write operation.
+ if cmd == 'ADDRESS READ':
+ self.warn_upon_invalid_slave(databyte)
+ self.state = 'READ REGS'
+ elif cmd == 'ADDRESS WRITE':
+ self.state = 'WRITE REGS'
+ elif self.state == 'READ REGS':
+ if cmd == 'DATA READ':
+ handle_reg = getattr(self, 'handle_reg_0x%02x' % self.reg)
+ handle_reg(databyte)
+ elif cmd == 'STOP':
+ # TODO: Any output?
+ self.state = 'IDLE'
+ else:
+ # self.putx([0, ['Ignoring: %s (data=%s)' % (cmd, databyte)]])
+ pass
+ elif self.state == 'WRITE REGS':
+ if cmd == 'DATA WRITE':
+ self.handle_reg_write(databyte)
+ elif cmd == 'STOP':
+ # TODO: Any output?
+ self.state = 'IDLE'
+ else:
+ # self.putx([0, ['Ignoring: %s (data=%s)' % (cmd, databyte)]])
+ pass
+ else:
+ raise Exception('Invalid state: %s' % self.state)
+
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