obd_sensors.py

#!/usr/bin/env python
###########################################################################
# obd_sensors.py
#
# Copyright 2004 Donour Sizemore (donour@uchicago.edu)
# Copyright 2009 Secons Ltd. (www.obdtester.com)
#
# This file is part of pyOBD.
#
# pyOBD 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.
#
# pyOBD 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 pyOBD; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
###########################################################################


def hex_to_int(text):
    return int(text, 16)


def maf(code):
    code = hex_to_int(code)
    return code * 0.00132276


def throttle_pos(code):
    code = hex_to_int(code)
    return code * 100.0 / 255.0


def intake_m_pres(code):  # in kPa
    code = hex_to_int(code)
    return code / 0.14504


def rpm(code):
    code = hex_to_int(code)
    return code / 4


def speed(code):
    code = hex_to_int(code)
    return code / 1.609


def percent_scale(code):
    code = hex_to_int(code)
    return code * 100.0 / 255.0


def timing_advance(code):
    code = hex_to_int(code)
    return (code - 128) / 2.0


def sec_to_min(code):
    code = hex_to_int(code)
    return code / 60


def temp(code):
    code = hex_to_int(code)
    c = code - 40
    return 32 + (9 * c / 5)


def cpass(code):
    # fixme
    return code


def fuel_trim_percent(code):
    code = hex_to_int(code)
    # return (code - 128.0) * 100.0 / 128
    return (code - 128) * 100 / 128


def dtc_decrypt(code):
    # first byte is byte after PID and without spaces
    num = hex_to_int(code[:2])  # A byte
    res = []

    if num & 0x80:  # is mil light on
        mil = 1
    else:
        mil = 0

    # bit 0-6 are the number of dtc's.
    num = num & 0x7f

    res.append(num)
    res.append(mil)

    numB = hex_to_int(code[2:4])  # B byte

    for i in range(0, 3):
        res.append(
            ((numB >> i) & 0x01) + ((numB >> (3 + i)) & 0x02)
        )

    numC = hex_to_int(code[4:6])  # C byte
    numD = hex_to_int(code[6:8])  # D byte

    for i in range(0, 7):
        res.append(
            ((numC >> i) & 0x01) + (((numD >> i) & 0x01) << 1)
        )

    res.append(((numD >> 7) & 0x01))  # EGR SystemC7  bit of different

    # return res
    return "#"


def hex_to_bitstring(text):
    bitstring = ""
    for i in text:
        if isinstance(i, str):
            v = hex_to_int(i)
            if v & 8:
                bitstring += '1'
            else:
                bitstring += '0'
            if v & 4:
                bitstring += '1'
            else:
                bitstring += '0'
            if v & 2:
                bitstring += '1'
            else:
                bitstring += '0'
            if v & 1:
                bitstring += '1'
            else:
                bitstring += '0'
    return bitstring


class Sensor:

    def __init__(
        self,
        shortName,
        sensorName,
        sensorcommand,
        sensorValueFunction,
        u
    ):
        self.shortname = shortName
        self.name = sensorName
        self.cmd = sensorcommand
        self.value = sensorValueFunction
        self.unit = u


SENSORS = [
    Sensor("pids", "Supported PIDs", "0100", hex_to_bitstring, ""),
    Sensor("dtc_status", "S-S DTC Cleared", "0101", dtc_decrypt, ""),
    Sensor("dtc_ff", "DTC C-F-F", "0102", cpass, ""),
    Sensor("fuel_status", "Fuel System Stat", "0103", cpass, ""),
    Sensor("load", "Calc Load Value", "01041", percent_scale, ""),
    Sensor("temp", "Coolant Temp", "0105", temp, "F"),
    Sensor("short_term_fuel_trim_1", "S-T Fuel Trim", "0106", fuel_trim_percent, "%"),
    Sensor("long_term_fuel_trim_1", "L-T Fuel Trim", "0107", fuel_trim_percent, "%"),
    Sensor("short_term_fuel_trim_2", "S-T Fuel Trim", "0108", fuel_trim_percent, "%"),
    Sensor("long_term_fuel_trim_2", "L-T Fuel Trim", "0109", fuel_trim_percent, "%"),
    Sensor("fuel_pressure", "FuelRail Pressure", "010A", cpass, ""),
    Sensor("manifold_pressure", "Intk Manifold", "010B", intake_m_pres, "psi"),
    Sensor("rpm", "Engine RPM", "010C1", rpm, ""),
    Sensor("speed", "Vehicle Speed", "010D1", speed, "MPH"),
    Sensor("timing_advance", "Timing Advance", "010E", timing_advance, "degrees"),
    Sensor("intake_air_temp", "Intake Air Temp", "010F", temp, "F"),
    Sensor("maf", "AirFlow Rate(MAF)", "0110", maf, "lb/min"),
    Sensor("throttle_pos", "Throttle Position", "01111", throttle_pos, "%"),
    Sensor("secondary_air_status", "2nd Air Status", "0112", cpass, ""),
    Sensor("o2_sensor_positions", "Loc of O2 sensors", "0113", cpass, ""),
    Sensor("o211", "O2 Sensor: 1 - 1", "0114", fuel_trim_percent, "%"),
    Sensor("o212", "O2 Sensor: 1 - 2", "0115", fuel_trim_percent, "%"),
    Sensor("o213", "O2 Sensor: 1 - 3", "0116", fuel_trim_percent, "%"),
    Sensor("o214", "O2 Sensor: 1 - 4", "0117", fuel_trim_percent, "%"),
    Sensor("o221", "O2 Sensor: 2 - 1", "0118", fuel_trim_percent, "%"),
    Sensor("o222", "O2 Sensor: 2 - 2", "0119", fuel_trim_percent, "%"),
    Sensor("o223", "O2 Sensor: 2 - 3", "011A", fuel_trim_percent, "%"),
    Sensor("o224", "O2 Sensor: 2 - 4", "011B", fuel_trim_percent, "%"),
    Sensor("obd_standard", "OBD Designation", "011C", cpass, ""),
    Sensor("o2_sensor_position_b", "Loc of O2 sensor", "011D", cpass, ""),
    Sensor("aux_input", "Aux input status", "011E", cpass, ""),
    Sensor("engine_time", "Engine Start MIN", "011F", sec_to_min, "min"),
    Sensor("engine_mil_time", "Engine Run MIL", "014D", sec_to_min, "min"),
]


def test():
    for i in SENSORS:
        print i.name, i.value("F")


if __name__ == "__main__":
    test()