From 6f213e97c347079f737e511c17943a9c57005610 Mon Sep 17 00:00:00 2001
From: Yannis Huber <32066446+yannishuber@users.noreply.github.com>
Date: Fri, 3 Apr 2020 13:11:46 +0200
Subject: [PATCH] Add driver for TMP102 low-power digital temperature sensor
 (#141)

* tmp102: add driver and example
---
 README.md               |  3 ++-
 examples/tmp102/main.go | 28 ++++++++++++++++++++
 tmp102/registers.go     | 18 +++++++++++++
 tmp102/tmp102.go        | 58 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 106 insertions(+), 1 deletion(-)
 create mode 100644 examples/tmp102/main.go
 create mode 100644 tmp102/registers.go
 create mode 100644 tmp102/tmp102.go

diff --git a/README.md b/README.md
index 767bcd2..b7a8f3e 100644
--- a/README.md
+++ b/README.md
@@ -52,7 +52,7 @@ func main() {
 
 ## Currently supported devices
 
-The following 45 devices are supported.
+The following 46 devices are supported.
 
 | Device Name | Interface Type |
 |----------|-------------|
@@ -101,6 +101,7 @@ The following 45 devices are supported.
 | [Waveshare 2.13" e-paper display](https://www.waveshare.com/w/upload/e/e6/2.13inch_e-Paper_Datasheet.pdf) | SPI |
 | [Waveshare 2.13" (B & C) e-paper display](https://www.waveshare.com/w/upload/d/d3/2.13inch-e-paper-b-Specification.pdf) | SPI |
 | [WS2812 RGB LED](https://cdn-shop.adafruit.com/datasheets/WS2812.pdf) | GPIO |
+| [TMP102 I2C Temperature Sensor](https://download.mikroe.com/documents/datasheets/tmp102-data-sheet.pdf) | I2C |
 
 ## Contributing
 
diff --git a/examples/tmp102/main.go b/examples/tmp102/main.go
new file mode 100644
index 0000000..5d764b4
--- /dev/null
+++ b/examples/tmp102/main.go
@@ -0,0 +1,28 @@
+package main
+
+import (
+	"fmt"
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/tmp102"
+)
+
+func main() {
+	machine.I2C0.Configure(machine.I2CConfig{
+		Frequency: machine.TWI_FREQ_400KHZ,
+	})
+
+	thermo := tmp102.New(machine.I2C0)
+	thermo.Configure(tmp102.Config{})
+
+	for {
+
+		temp, _ := thermo.ReadTemperature()
+
+		print(fmt.Sprintf("%.2f°C\r\n", float32(temp)/1000.0))
+
+		time.Sleep(time.Millisecond * 1000)
+	}
+
+}
diff --git a/tmp102/registers.go b/tmp102/registers.go
new file mode 100644
index 0000000..644a9d5
--- /dev/null
+++ b/tmp102/registers.go
@@ -0,0 +1,18 @@
+package tmp102
+
+const (
+	// Default I2C address
+	Address = 0x48
+
+	// Temperature register address
+	RegTemperature = 0x00
+
+	// Configuration register address
+	RegConfiguration = 0x01
+
+	// Low limit register address
+	RegLimitLow = 0x02
+
+	// High limit register address
+	RegLimitHigh = 0x03
+)
diff --git a/tmp102/tmp102.go b/tmp102/tmp102.go
new file mode 100644
index 0000000..5c568d4
--- /dev/null
+++ b/tmp102/tmp102.go
@@ -0,0 +1,58 @@
+// Package tmp102 implements a driver for the TMP102 digital temperature sensor.
+//
+// Datasheet: https://download.mikroe.com/documents/datasheets/tmp102-data-sheet.pdf
+
+package tmp102 // import "tinygo.org/x/drivers/tmp102"
+
+import (
+	"machine"
+)
+
+// Device holds the already configured I2C bus and the address of the sensor.
+type Device struct {
+	bus     machine.I2C
+	address uint8
+}
+
+// Config is the configuration for the TMP102.
+type Config struct {
+	Address uint8
+}
+
+// New creates a new TMP102 connection. The I2C bus must already be configured.
+func New(bus machine.I2C) Device {
+	return Device{
+		bus: bus,
+	}
+}
+
+// Configure initializes the sensor with the given parameters.
+func (d *Device) Configure(cfg Config) {
+	if cfg.Address == 0 {
+		cfg.Address = Address
+	}
+
+	d.address = cfg.Address
+}
+
+// Reads the temperature from the sensor and returns it in celsius milli degrees (°C/1000).
+func (d *Device) ReadTemperature() (temperature int32, err error) {
+
+	tmpData := make([]byte, 2)
+
+	err = d.bus.ReadRegister(d.address, RegTemperature, tmpData)
+
+	if err != nil {
+		return
+	}
+
+	temperatureSum := int32((int16(tmpData[0])<<8 | int16(tmpData[1])) >> 4)
+
+	if (temperatureSum & int32(1<<11)) == int32(1<<11) {
+		temperatureSum |= int32(0xf800)
+	}
+
+	temperature = temperatureSum * 625
+
+	return temperature / 10, nil
+}