succd: rewrite processing loop

succbone/succd/http.go

@@ -36,24 +36,6 @@ func formatVolts(v float32) string {
 	return fmt.Sprintf("%.4f V", v)
 }
 
-// formatMbar formats a millibar value using scientific notation and returns a
-// HTML fragment (for superscript support).
-func formatMbar(v float32) template.HTML {
-	exp := 0
-	for v < 1 {
-		v *= 10
-		exp -= 1
-	}
-	for v >= 10 {
-		v /= 10
-		exp += 1
-	}
-	res := fmt.Sprintf("%.3f", v)
-	res += fmt.Sprintf(" x 10<sup>%d</sup>", exp)
-	res += " mbar"
-	return template.HTML(res)
-}
-
 // apiData is the data model served to the user via HTTP/WebSockets
 type apiData struct {
 	// Safety interlocks.
@@ -102,7 +84,8 @@ type apiData struct {
 // not being served via websockets).
 func (s *webServer) apiData(skipSystem bool) *apiData {
 	state := s.d.snapshot()
-	volts, mbar := state.pirani()
+	volts := state.piraniVolts100.avg
+	mbar := state.piraniMbar100.mbar
 	rough, high := state.vacuumStatus()
 
 	var hostname, load string
@@ -125,7 +108,7 @@ func (s *webServer) apiData(skipSystem bool) *apiData {
 	ad.Safety.Failsafe = state.safety.failsafe
 	ad.Safety.HighPressure = state.safety.highPressure
 	ad.Pirani.Volts = formatVolts(volts)
-	ad.Pirani.Mbar = formatMbar(mbar)
+	ad.Pirani.Mbar = formatMbarHTML(mbar)
 	ad.Pirani.MbarFloat = mbar
 	ad.Pumps.RPOn = state.rpOn
 	ad.Pumps.DPOn = state.dpOn
@@ -182,7 +165,7 @@ func (s *webServer) viewMetrics(w http.ResponseWriter, r *http.Request) {
 	// library.
 	// TODO(q3k): serve the rest of the data model
 	state := s.d.snapshot()
-	_, mbar := state.pirani()
+	mbar := state.piraniMbar100.mbar
 	fmt.Fprintf(w, "# HELP sem_pressure_mbar Pressure in the SEM chamber, in millibar\n")
 	fmt.Fprintf(w, "# TYPE sem_pressure_mbar gauge\n")
 	fmt.Fprintf(w, "sem_pressure_mbar %f\n", mbar)

succbone/succd/main.go

@@ -28,6 +28,8 @@ func main() {
 
 	d := daemon{}
 	d.daemonState.rpOn = true
+	d.daemonState.piraniVolts3.limit = 3
+	d.daemonState.piraniVolts100.limit = 100
 
 	d.aboveRough.threshold = float64(flagPressureThresholdRough)
 	d.aboveHigh.threshold = float64(flagPressureThresholdHigh)

succbone/succd/process.go

@@ -28,43 +28,37 @@ type daemon struct {
 	daemonState
 }
 
-// momentaryOutput is an output that can be triggered for 500ms.
-type momentaryOutput struct {
-	// output of the block.
-	output bool
-	// scheduledOff is when the block should be outputting false again.
-	scheduledOff time.Time
+// daemonState contains all the state of the daemon. A copy of it can be
+// requested for consumers, eg. the web view.
+type daemonState struct {
+	safety struct {
+		// failsafe mode is enabled when the pirani gauge appears to be
+		// disconnected, and is disabled only when an atmosphere is read.
+		failsafe bool
+		// highPressure mode is enabled when the pressure reading is above 1e-1
+		// mbar, locking out the diffusion pump from being enabled.
+		highPressure bool
 	}
 
-func (m *momentaryOutput) process() {
-	m.output = m.scheduledOff.After(time.Now())
+	piraniVolts100 ringbufferInput
+	piraniMbar100  pfeifferVoltsToMbar
+	piraniVolts3   ringbufferInput
+	piraniMbar3    pfeifferVoltsToMbar
+
+	rpOn bool
+	dpOn bool
+
+	vent       momentaryOutput
+	pumpdown   momentaryOutput
+	aboveRough thresholdOutput
+	aboveHigh  thresholdOutput
 }
 
-func (m *momentaryOutput) trigger() {
-	m.scheduledOff = time.Now().Add(time.Millisecond * 500)
-}
-
-// thresholdOutput outputs true if a given value is above a setpoint/threshold.
-// It contains debounce logic for processing noisy analog signals.
-type thresholdOutput struct {
-	// output of the block.
-	output bool
-	// debounce is when the debouncer should be inactive again.
-	debounce time.Time
-	// threshold is the setpoint of the block.
-	threshold float64
-}
-
-func (t *thresholdOutput) process(value float64) {
-	if time.Now().Before(t.debounce) {
+func (d *daemonState) vacuumStatus() (rough, high bool) {
+	rough = !d.aboveRough.output
+	high = !d.aboveHigh.output
 	return
 }
-	new := value > t.threshold
-	if new != t.output {
-		t.output = new
-		t.debounce = time.Now().Add(time.Second * 5)
-	}
-}
 
 // process runs the pain acquisition and control loop of succd.
 func (d *daemon) process(ctx context.Context) {
@@ -96,56 +90,60 @@ func (d *daemon) processOnce(_ context.Context) error {
 	d.mu.Lock()
 	defer d.mu.Unlock()
 
-	// Process pirani ringbuffer.
-	d.adcPiraniVolts = append(d.adcPiraniVolts, v)
-	trim := len(d.adcPiraniVolts) - 100
-	if trim > 0 {
-		d.adcPiraniVolts = d.adcPiraniVolts[trim:]
-	}
+	// Process pirani ringbuffers.
+	d.piraniVolts3.process(v)
+	d.piraniMbar3.process(d.piraniVolts3.avg)
+	d.piraniVolts100.process(v)
+	d.piraniMbar100.process(d.piraniVolts100.avg)
 
 	d.pumpdown.process()
 	d.vent.process()
 
-	_, mbar := d.daemonState.pirani()
-	d.aboveRough.process(float64(mbar))
-	d.aboveHigh.process(float64(mbar))
-
-	// Check if the pirani gauge is disconnected. Note: this will assume the
-	// pirani gauge is connected for the first couple of processing runs as
-	// samples are still being captured.
-	if d.piraniDetection() == piraniDetectionDisconnected {
+	// Run safety checks based on small ringbuffer.
+	if d.piraniVolts3.saturated() {
+		mbar := d.piraniMbar3.mbar
+		if !d.safety.failsafe && mbar < 4e-6 {
 			// Unrealistic result, Pirani probe probably disconnected. Failsafe mode.
 			if !d.safety.failsafe {
 				d.safety.failsafe = true
 				klog.Errorf("Pirani probe seems disconnected; enabling failsafe mode")
 			}
-	} else {
-		if d.safety.failsafe {
-			if mbar >= 1e2 {
+		}
+		if d.safety.failsafe && mbar > 1e2 {
 			d.safety.failsafe = false
-				klog.Infof("Values are plausible again; quitting failsafe mode")
-			}
-		}
+			klog.Infof("Pirani probe value (%s) is plausible again; quitting failsafe mode", formatMbar(mbar))
 		}
 
-	if mbar >= 1e-1 {
-		if !d.safety.highPressure {
+		if !d.safety.highPressure && mbar >= 1e-1 {
 			d.safety.highPressure = true
-			klog.Errorf("Pressure is too high; enabling diffusion pump lockout")
+			klog.Warningf("Pressure is too high (%s mbar); enabling diffusion pump lockout", formatMbar(mbar))
 		}
-	} else if mbar < (1e-1)-(1e-2) {
-		if d.safety.highPressure {
+		if d.safety.highPressure && mbar < (1e-1)-(1e-2) {
 			d.safety.highPressure = false
-			klog.Infof("Pressure is low enough for diffusion pump operation; quitting diffusion pump lockout")
+			klog.Infof("Pressure is low enough (%s mbar) for diffusion pump operation; quitting diffusion pump lockout", formatMbar(mbar))
 		}
+	} else {
+		d.safety.failsafe = true
+		d.safety.highPressure = true
 	}
 
+	// Control threhold/feedback values based on main pirani ringbuffer, failing
+	// safe if not enough data is present.
+	if d.piraniVolts100.saturated() {
+		mbar := d.piraniMbar100.mbar
+		d.aboveRough.process(float64(mbar))
+		d.aboveHigh.process(float64(mbar))
+	} else {
+		d.aboveRough.output = true
+		d.aboveHigh.output = true
+	}
+
+	// Apply safety overrides.
 	if d.safety.failsafe {
 		d.aboveRough.output = true
 		d.aboveHigh.output = true
 		d.dpOn = false
 	}
-
 	if d.safety.highPressure {
 		d.dpOn = false
 	}

succbone/succd/process_blocks.go

@@ -0,0 +1,88 @@
+package main
+
+import (
+	"math"
+	"time"
+)
+
+// momentaryOutput is an output that can be triggered for 500ms.
+type momentaryOutput struct {
+	// output of the block.
+	output bool
+	// scheduledOff is when the block should be outputting false again.
+	scheduledOff time.Time
+}
+
+func (m *momentaryOutput) process() {
+	m.output = m.scheduledOff.After(time.Now())
+}
+
+func (m *momentaryOutput) trigger() {
+	m.scheduledOff = time.Now().Add(time.Millisecond * 500)
+}
+
+// thresholdOutput outputs true if a given value is above a setpoint/threshold.
+// It contains debounce logic for processing noisy analog signals.
+type thresholdOutput struct {
+	// output of the block.
+	output bool
+	// debounce is when the debouncer should be inactive again.
+	debounce time.Time
+	// threshold is the setpoint of the block.
+	threshold float64
+}
+
+func (t *thresholdOutput) process(value float64) {
+	if time.Now().Before(t.debounce) {
+		return
+	}
+	new := value > t.threshold
+	if new != t.output {
+		t.output = new
+		t.debounce = time.Now().Add(time.Second * 5)
+	}
+}
+
+// ringbufferInput accumulates analog data up to limit samples, and calculates
+// an average.
+type ringbufferInput struct {
+	data  []float32
+	limit uint
+	// avg is the mean average of the samples in data, or 0.0 if no data is
+	// present yet. This is the main output of the block.
+	avg float32
+}
+
+func (r *ringbufferInput) process(input float32) {
+	// TODO(q3k): use actual ringbuffer
+	// TODO(q3k): optimize average calculation
+	// TODO(q3k): precalculate value in mbar
+	r.data = append(r.data, input)
+	trim := len(r.data) - int(r.limit)
+	if trim > 0 {
+		r.data = r.data[trim:]
+	}
+	avg := float32(0.0)
+	for _, v := range r.data {
+		avg += v
+	}
+	if len(r.data) != 0 {
+		avg /= float32(len(r.data))
+	}
+	r.avg = avg
+}
+
+// saturated returns true if the number of samples is at the configured limit.
+func (r *ringbufferInput) saturated() bool {
+	return len(r.data) >= int(r.limit)
+}
+
+type pfeifferVoltsToMbar struct {
+	mbar float32
+}
+
+func (p *pfeifferVoltsToMbar) process(volts float32) {
+	// Per Pirani probe docs.
+	bar := math.Pow(10.0, float64(volts)-8.5)
+	p.mbar = float32(bar * 1000.0)
+}

succbone/succd/process_state.go

@@ -1,84 +0,0 @@
-package main
-
-import "math"
-
-// daemonState contains all the state of the daemon. A copy of it can be
-// requested for consumers, eg. the web view.
-type daemonState struct {
-	safety safetyStatus
-
-	// adcPiraniVolts is a moving window of read ADC values, used to calculate a
-	// moving average.
-	adcPiraniVolts []float32
-	rpOn           bool
-	dpOn           bool
-
-	vent       momentaryOutput
-	pumpdown   momentaryOutput
-	aboveRough thresholdOutput
-	aboveHigh  thresholdOutput
-}
-
-type safetyStatus struct {
-	// failsafe mode is enabled when the pirani gauge appears to be
-	// disconnected, and is disabled only when an atmosphere is read.
-	failsafe bool
-	// highPressure mode is enabled when the pressure reading is above 1e-1
-	// mbar, locking out the diffusion pump from being enabled.
-	highPressure bool
-}
-
-type piraniDetection uint
-
-const (
-	// piraniDetectionUnknown means the system isn't yet sure whether the pirani
-	// gauge is connected.
-	piraniDetectionUnknown piraniDetection = iota
-	// piraniDetectionConnected means the system assumes the pirani gauge is
-	// connected.
-	piraniDetectionConnected = iota
-	// piraniDetectionDisconnected means the system assumes the pirani gauge is
-	// disconnected.
-	piraniDetectionDisconnected = iota
-)
-
-// piraniDetection guesses whether the pirani gauge is connected.
-func (d *daemonState) piraniDetection() piraniDetection {
-	if len(d.adcPiraniVolts) < 3 {
-		return piraniDetectionUnknown
-	}
-	volts := float32(0.0)
-	for _, v := range d.adcPiraniVolts[len(d.adcPiraniVolts)-3:] {
-		volts += v
-	}
-	volts /= 3.0
-
-	bar := math.Pow(10.0, float64(volts)-8.5)
-	mbar := float32(bar * 1000.0)
-
-	if mbar < 4e-6 {
-		return piraniDetectionDisconnected
-	}
-	return piraniDetectionConnected
-}
-
-func (d *daemonState) pirani() (volts float32, mbar float32) {
-	volts = 0.0
-	for _, v := range d.adcPiraniVolts {
-		volts += v
-	}
-	if len(d.adcPiraniVolts) != 0 {
-		volts /= float32(len(d.adcPiraniVolts))
-	}
-
-	// Per Pirani probe docs.
-	bar := math.Pow(10.0, float64(volts)-8.5)
-	mbar = float32(bar * 1000.0)
-	return
-}
-
-func (d *daemonState) vacuumStatus() (rough, high bool) {
-	rough = !d.aboveRough.output
-	high = !d.aboveHigh.output
-	return
-}

succbone/succd/scientific.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"html/template"
 	"strconv"
 )
 
@@ -16,8 +17,25 @@ func (s *ScientificNotationValue) UnmarshalText(text []byte) error {
 	return nil
 }
 
-func (s *ScientificNotationValue) MarshalText() ([]byte, error) {
-	v := float64(*s)
+// formatMbarHTML formats a millibar value using scientific notation and returns
+// a HTML fragment (for superscript support).
+func formatMbarHTML(v float32) template.HTML {
+	exp := 0
+	for v < 1 {
+		v *= 10
+		exp -= 1
+	}
+	for v >= 10 {
+		v /= 10
+		exp += 1
+	}
+	res := fmt.Sprintf("%.3f", v)
+	res += fmt.Sprintf(" x 10<sup>%d</sup>", exp)
+	res += " mbar"
+	return template.HTML(res)
+}
+
+func formatMbar(v float32) string {
 	exp := 0
 	for v < 1 {
 		v *= 10
@@ -29,5 +47,11 @@ func (s *ScientificNotationValue) MarshalText() ([]byte, error) {
 	}
 	res := fmt.Sprintf("%.3f", v)
 	res += fmt.Sprintf("e%d", exp)
+	return res
+}
+
+func (s *ScientificNotationValue) MarshalText() ([]byte, error) {
+	v := float32(*s)
+	res := formatMbar(v)
 	return []byte(res), nil
 }