From 7054cdbeea0123f3c6d8f1953d84dea8b4368686 Mon Sep 17 00:00:00 2001 From: Max Matveev Date: Sat, 6 Feb 2016 00:13:54 -0800 Subject: [PATCH] ds18b20 - requires https://github.com/kidoman/embd/pull/54 --- samples/ds18b20.go | 78 ++++++++++++++++++++ sensor/ds18b20/ds18b20.go | 146 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 224 insertions(+) create mode 100644 samples/ds18b20.go create mode 100644 sensor/ds18b20/ds18b20.go diff --git a/samples/ds18b20.go b/samples/ds18b20.go new file mode 100644 index 0000000..4ea8cf5 --- /dev/null +++ b/samples/ds18b20.go @@ -0,0 +1,78 @@ +// +build ignore + +package main + +import ( + "fmt" + "strings" + + "github.com/zlowred/embd" + "github.com/zlowred/embd/sensor/ds18b20" + _ "github.com/zlowred/embd/host/rpi" +) + +func main() { + if err := embd.InitW1(); err != nil { + panic(err) + } + defer embd.CloseW1() + + w1 := embd.NewW1Bus(0) + + devs, err := w1.ListDevices() + + if err != nil { + panic(err) + } + + var name string = "" + for _, dev := range devs { + if strings.HasPrefix(dev, "28-") { + name = dev + break + } + } + + if name == "" { + fmt.Println("No DS18B20 devices found") + } + + fmt.Printf("Using DS18B20 device %s\n", name) + w1d, err := w1.Open(name) + + if err != nil { + panic(err) + } + + sensor := ds18b20.New(w1d) + + err = sensor.SetResolution(ds18b20.Resolution_12bit) + + if err != nil { + panic(err) + } + + err = sensor.ReadTemperature() + + if err != nil { + panic(err) + } + + fmt.Printf("Measured temperature: %vC\n", sensor.Celsius()) + fmt.Printf("Measured temperature: %vF\n", sensor.Fahrenheit()) + + err = sensor.SetResolution(ds18b20.Resolution_9bit) + + if err != nil { + panic(err) + } + + err = sensor.ReadTemperature() + + if err != nil { + panic(err) + } + + fmt.Printf("Measured temperature: %vC\n", sensor.Celsius()) + fmt.Printf("Measured temperature: %vF\n", sensor.Fahrenheit()) +} diff --git a/sensor/ds18b20/ds18b20.go b/sensor/ds18b20/ds18b20.go new file mode 100644 index 0000000..1342448 --- /dev/null +++ b/sensor/ds18b20/ds18b20.go @@ -0,0 +1,146 @@ +// Support for the very popular DS18B20 1-WIre temperature sensor +package ds18b20 +import ( + "github.com/zlowred/embd" + "errors" + "sync" +) + +type DS18B20_Resolution int + +const ( + Resolution_9bit DS18B20_Resolution = iota + Resolution_10bit + Resolution_11bit + Resolution_12bit +) + +var ds18b20_crc_data = [...]byte{ + 0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65, + 157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220, + 35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98, + 190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255, + 70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7, + 219, 133, 103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154, + 101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36, + 248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185, + 140, 210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113, 147, 205, + 17, 79, 173, 243, 112, 46, 204, 146, 211, 141, 111, 49, 178, 236, 14, 80, + 175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82, 176, 238, + 50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115, + 202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139, + 87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22, + 233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168, + 116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53, +} +// DS18B20 represents a DS18B20 temperature sensor. +type DS18B20 struct { + Device embd.W1Device + + Raw int16 + mu sync.Mutex +} + +// New returns a handle to a DS18B20 sensor. +func New(device embd.W1Device) *DS18B20 { + return &DS18B20{Device: device} +} + +func ds18b20_crc(data []byte) byte { + var crc byte = 0 + var x byte + for _, x := range data { + crc = ds18b20_crc_data[crc ^ x] + } + return x +} + +func (sensor *DS18B20) ReadTemperature() error { + sensor.mu.Lock() + defer sensor.mu.Unlock() + + err := sensor.Device.WriteByte(0x44) + + if err != nil { + return err + } + + for ret, err := sensor.Device.ReadByte(); ret == 0 && err != nil; {} + + if err != nil { + return err + } + + err = sensor.Device.WriteByte(0xBE) + + if err != nil { + return err + } + + res, err := sensor.Device.ReadBytes(9) + + if err != nil { + return err + } + + crc := ds18b20_crc(res[:8]) + + if crc != res[8] { + errors.New("CRC error") + } + + sensor.Raw = int16(res[1]) * 256 + int16(res[0]) + cfg := res[4] & 0x60 + + switch cfg { + case 0x00: + sensor.Raw &^= 7 + case 0x20: + sensor.Raw &^= 3 + case 0x40: + sensor.Raw &^= 1 + } + + return nil +} + +func (sensor *DS18B20) Celsius() float32 { + return float32(sensor.Raw) * 0.0625 +} + +func (sensor *DS18B20) Fahrenheit() float32 { + return float32(sensor.Raw) * 0.1125 + 32. +} + +func (sensor *DS18B20) SetResolution(resoultion DS18B20_Resolution) error { + sensor.mu.Lock() + defer sensor.mu.Unlock() + + err := sensor.Device.WriteByte(0x4E) + if err != nil { + return err + } + err = sensor.Device.WriteByte(0x00) + if err != nil { + return err + } + err = sensor.Device.WriteByte(0x00) + if err != nil { + return err + } + switch resoultion { + case Resolution_9bit: + err = sensor.Device.WriteByte(0x1F) + case Resolution_10bit: + err = sensor.Device.WriteByte(0x3F) + case Resolution_11bit: + err = sensor.Device.WriteByte(0x5F) + case Resolution_12bit: + err = sensor.Device.WriteByte(0x7F) + } + if err != nil { + return err + } + return nil +} +