Commit 1eb668e515ffd10df12e1d9511a97c2b9bccb899 - sousvide

Add GPIO heater relay support. Will Haldean Brown 9 years ago

4 changed file(s) with 177 addition(s) and 48 deletion(s). Raw diff Collapse all Expand all

+127

-0

control.go less more

	0	// hat tip to github.com/aqua/raspberrypi for inspiration for the GPIO code
	1
	2	package main
	3
	4	import (
	5	"flag"
	6	"fmt"
	7	"math/rand"
	8	"os"
	9	"time"
	10	)
	11
	12	const HeaterGpioPin = 18
	13
	14	var StubGpio = flag.Bool("stub_gpio", false, "stub GPIO calls for testing")
	15
	16	func checkHeaterExported() error {
	17	_, err := os.Stat(fmt.Sprintf("/sys/class/gpio/gpio%d", HeaterGpioPin))
	18	if err == nil {
	19	return nil
	20	}
	21	if !os.IsNotExist(err) {
	22	return err
	23	}
	24
	25	fd, err := os.OpenFile(
	26	"/sys/class/gpio/export", os.O_WRONLY \| os.O_SYNC, 0666)
	27	if err != nil {
	28	return err
	29	}
	30	defer fd.Close()
	31
	32	_, err = fmt.Fprintf(fd, "%d\n", HeaterGpioPin)
	33	return err
	34	}
	35
	36	func setHeaterOutputMode() error {
	37	fd, err := os.OpenFile(
	38	fmt.Sprintf("/sys/class/gpio/gpio%d/direction", HeaterGpioPin),
	39	os.O_WRONLY \| os.O_SYNC, 0666)
	40	if err != nil {
	41	return err
	42	}
	43	defer fd.Close()
	44
	45	fmt.Fprintf(fd, "out")
	46	return nil
	47	}
	48
	49	func (s *SousVide) InitGpio() error {
	50	s.Gpio.Stub = *StubGpio
	51	if s.Gpio.Stub {
	52	s.Gpio.HeaterFd = os.Stdout
	53	return nil
	54	}
	55
	56	err := checkHeaterExported()
	57	if err != nil {
	58	return err
	59	}
	60	err = setHeaterOutputMode()
	61	if err != nil {
	62	return err
	63	}
	64	s.Gpio.HeaterFd, err = os.OpenFile(
	65	fmt.Sprintf("/sys/class/gpio/gpio%d/value", HeaterGpioPin),
	66	os.O_WRONLY \| os.O_SYNC, 0666)
	67	if err != nil {
	68	return err
	69	}
	70	return nil
	71	}
	72
	73	func (s *SousVide) StartControlLoop() {
	74	tick := time.Tick(InterruptDelay)
	75	for _ = range tick {
	76	s.DataLock.Lock()
	77	s.UpdateHardware()
	78
	79	if s.Heating {
	80	s.Temp += Celsius(10 * rand.Float64())
	81	} else {
	82	s.Temp -= Celsius(10 * rand.Float64())
	83	}
	84
	85	co := s.ControllerResult()
	86	s.Heating = co > 0
	87
	88	s.checkpoint()
	89	s.DataLock.Unlock()
	90	}
	91	}
	92
	93	func (s *SousVide) ControllerResult() Celsius {
	94	s.lastPOutput = s.Pid.P * float64(s.Error())
	95
	96	if len(s.History) > 0 {
	97	integral := float64(0)
	98	for _, h := range s.History {
	99	integral += h.AbsError
	100	}
	101	integral /= float64(len(s.History))
	102	s.lastIOutput = s.Pid.I * integral
	103	}
	104
	105	// ignore derivative term if we have no history to use
	106	if len(s.History) > LowpassSamples {
	107	// use weighted window over three samples instead of two to act as a
	108	// low-pass filter
	109	N := len(s.History)
	110	d := (s.History[N-LowpassSamples-1].Temp - s.History[N-1].Temp) / 2
	111	s.lastDOutput = s.Pid.D * d
	112	}
	113
	114	s.lastControl = s.lastPOutput + s.lastIOutput + s.lastDOutput
	115	return Celsius(s.lastControl)
	116	}
	117
	118	func (s *SousVide) UpdateHardware() {
	119	var heatVal string
	120	if s.Heating {
	121	heatVal = "1\n"
	122	} else {
	123	heatVal = "0\n"
	124	}
	125	fmt.Fprintf(s.Gpio.HeaterFd, heatVal)
	126	}

+31

-46

sousvide.go less more

0	0	package main
1	1
2	2	import (
3		"log"
4		"math/rand"
	3	"flag"
	4	"fmt"
	5	"math"
	6	"os"
5	7	"sync"
6	8	"time"
7	9	)

10	12	InterruptDelay = 1 * time.Second
11	13	LogFile = "runlog.txt"
12	14	HistoryLength = 2048
13		LowpassSamples = 3
	15	LowpassSamples = 2
	16	AccErrorWindow = 32
14	17	)
15	18
16	19	type SousVide struct {

19	22	Target Celsius
20	23	History []HistorySample
21	24	Pid PidParams
	25	Gpio GpioParams
22	26	DataLock sync.Mutex
	27	AccError float64
23	28	lastPOutput float64
24	29	lastIOutput float64
25	30	lastDOutput float64

32	37	Temp float64
33	38	Target float64
34	39	AbsError float64
	40	AccError float64
35	41	Pid PidParams
36	42	POutput float64
37	43	IOutput float64

43	49	P float64
44	50	I float64
45	51	D float64
	52	}
	53
	54	type GpioParams struct {
	55	ThermFd *os.File
	56	HeaterFd *os.File
	57	Stub bool
46	58	}
47	59
48	60	type Celsius float64

60	72	Temp: float64(s.Temp),
61	73	Target: float64(s.Target),
62	74	AbsError: float64(s.Error()),
	75	AccError: s.AccError,
63	76	Pid: s.Pid,
64	77	POutput: s.lastPOutput,
65	78	IOutput: s.lastIOutput,

77	90	} else {
78	91	s.History = append(s.History, s.Snapshot())
79	92	}
80		}
81	93
82		func (s *SousVide) StartControlLoop() {
83		tick := time.Tick(InterruptDelay)
84		for _ = range tick {
85		s.DataLock.Lock()
86		if s.Heating {
87		s.Temp += Celsius(10 * rand.Float64())
88		} else {
89		s.Temp -= Celsius(10 * rand.Float64())
90		}
91		log.Printf("read temperature %f deg C", s.Temp)
92
93		co := s.ControllerResult()
94		s.Heating = co > 0
95		log.Printf("controller returned %v", co)
96
97		s.checkpoint()
98		s.DataLock.Unlock()
	94	s.AccError = 0
	95	N := len(s.History)
	96	l := float64(0)
	97	for i := N - 1; i >= N-AccErrorWindow-1 && i >= 0; i-- {
	98	s.AccError += math.Abs(s.History[i].AbsError)
	99	l++
99	100	}
100		}
101
102		func (s *SousVide) ControllerResult() Celsius {
103		s.lastPOutput = s.Pid.P * float64(s.Error())
104
105		if len(s.History) > 0 {
106		integral := float64(0)
107		for _, h := range s.History {
108		integral += h.AbsError
109		}
110		integral /= float64(len(s.History))
111		s.lastIOutput = s.Pid.I * integral
112		}
113
114		// ignore derivative term if we have no history to use
115		if len(s.History) > LowpassSamples {
116		// use weighted window over three samples instead of two to act as a
117		// low-pass filter
118		N := len(s.History)
119		d := (s.History[N-LowpassSamples-1].Temp - s.History[N-1].Temp) / 2
120		s.lastDOutput = s.Pid.D * d
121		}
122
123		s.lastControl = s.lastPOutput + s.lastIOutput + s.lastDOutput
124		return Celsius(s.lastControl)
	101	s.AccError /= l
125	102	}
126	103
127	104	func (s *SousVide) SetTarget(target Celsius) {

137	114	}
138	115
139	116	func main() {
	117	flag.Parse()
	118
140	119	s := New()
141	120	s.Target = 200
142	121	s.Pid.P = 10
143	122	s.Pid.I = 0.1
144	123	s.Pid.D = 10
145	124
	125	err := s.InitGpio()
	126	if err != nil {
	127	fmt.Printf("could not initialize gpio: %v\n", err)
	128	return
	129	}
	130
146	131	go s.StartControlLoop()
147	132	s.StartServer()
148	133	}

+16

-0

static/index.html less more

49	49	width: 100pt;
50	50	text-align: right;
51	51	}
	52
	53	.subtext {
	54	display: block;
	55	font-size: 9pt;
	56	margin-top: -2pt;
	57	color: #CCC;
	58	}
52	59	</style>
53	60	<link href='http://fonts.googleapis.com/css?family=Source+Sans+Pro:400,700\|Source+Code+Pro' rel='stylesheet' type='text/css'>
54	61

86	93	<td class="label error_label">Error:</td>
87	94	<td class="val" id="err_td"><span id="abs_err"></span>° C</td>
88	95	</tr>
	96	<tr>
	97	<td class="label">
	98	Mean error per sample:
	99	<span class="subtext">
	100	Taken over 32-sample sliding window
	101	</span>
	102	</td>
	103	<td class="val">±<span id="acc_err"></span> °C/sample</td>
	104	</tr>
89	105	</table>
90	106	<img src="/plot" id="plot">
91	107	</section>

-2

static/sousvide.js less more

0		var tempElem, absErrElem, targetElem, absErrTdElem, heatingElem, plotElem
	0	var tempElem, absErrElem, targetElem, heatingElem, plotElem, accErrElem
1	1	var targetDisplayElem, targetChangeElem, targetInputElem
2	2	var pInputElem, iInputElem, dInputElem
3	3

23	23	$(tempElem).text(temp.toFixed(2));
24	24	$(targetElem).text(target.toFixed(2));
25	25	$(absErrElem).text((err >= 0 ? '+' : '') + err.toFixed(2));
	26	$(accErrElem).text(data.AccError.toFixed(2))
26	27
27	28	pInputElem.setAttribute('value', data.Pid.P)
28	29	iInputElem.setAttribute('value', data.Pid.I)

43	44	tempElem = document.getElementById('temp')
44	45	absErrElem = document.getElementById('abs_err')
45	46	targetElem = document.getElementById('target')
46		absErrTdElem = document.getElementById('err_td')
47	47	heatingElem = document.getElementById('heating')
48	48	plotElem = document.getElementById('plot')
	49	accErrElem = document.getElementById('acc_err')
49	50
50	51	targetChangeElem = document.getElementById('target_change')
51	52	targetDisplayElem = document.getElementById('target_display')