mirror of
https://github.com/kidoman/embd
synced 2024-10-31 23:38:44 +01:00
260 lines
9.7 KiB
Markdown
260 lines
9.7 KiB
Markdown
# embd [](https://travis-ci.org/kidoman/embd) [](http://godoc.org/github.com/kidoman/embd)
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**embd** is a hardware abstraction layer (HAL) for embedded systems.
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It allows you to start your hardware hack on easily available hobby boards
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(like the Raspberry Pi, BeagleBone Black, C.H.I.P., etc.) by giving you
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straight-forward access to the board's capabilities as well as a plethora of
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**sensors** (like accelerometers, gyroscopes, thermometers, etc.) and
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**controllers** (PWM generators, digital-to-analog convertors) for
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which it includes drivers. If you move to custom designed boards
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you have to throw away your code: you carry forward the effort
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where the HAL abstraction of EMBD will save you precious time.
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The overall strategy used in embd is to use Linux device drivers to access gpio pins,
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SPI and I2C buses, as well as interrupts. This makes it easy to port from one platform
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to another and it enables kernel code to handle the devices as efficiently as possible.
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What embd then adds is first a Golang library interface on top of the various Linux
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devices and then another layer of user-level drivers for specific sensors and controllers
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that are connected to gpio pins or one of the buses.
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Development supported and sponsored by [**SoStronk**](https://www.sostronk.com) and
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[**ThoughtWorks**](http://www.thoughtworks.com/).
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Also, you might be interested in: [Why Golang?](https://github.com/kidoman/embd/wiki/Why-Go)
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[Blog post introducing EMBD](http://kidoman.io/framework/embd.html)
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## Getting Started
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Install Go version 1.6 or later to make compiling for ARM easy.
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The set up your [GOPATH](http://golang.org/doc/code.html#GOPATH),
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and create your first .go file. We'll call it `simpleblinker.go`.
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```go
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package main
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import (
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"time"
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"github.com/kidoman/embd"
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_ "github.com/kidoman/embd/host/rpi" // This loads the RPi driver
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)
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func main() {
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for {
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embd.LEDToggle("LED0")
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time.Sleep(250 * time.Millisecond)
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}
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}
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```
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Then install the EMBD package:
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$ go get github.com/kidoman/embd
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Build the binary for linux/ARM:
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$ export GOOS=linux
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$ export GOARCH=arm
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$ go build simpleblinker.go
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Copy the cross-compiled binary to your RaspberryPi*:
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$ scp simpleblinker pi@192.168.2.2:~
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Then on the rPi run the program with ```sudo```*:
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$ sudo ./simpleblinker
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**You will now see the green LED (next to the always on power LED) blink every 1/4 sec.**
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**<nowiki>*</nowiki> Notes**
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* Assuming your RaspberryPi has an IP address of ```192.168.2.2```. Substitute as necessary
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* `sudo` (root) permission is required as we are controlling the hardware by writing to special files
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* This sample program is optimized for brevity and does not clean up after itself. Click here to
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see the [full version](https://github.com/kidoman/embd/blob/master/samples/fullblinker.go)
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## Getting Help
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Join the [slack channel](https://gophers.slack.com/archives/embd)
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## Platforms Supported
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* [RaspberryPi](http://www.raspberrypi.org/) (including [A+](http://www.raspberrypi.org/products/model-a-plus/) and [B+](http://www.raspberrypi.org/products/model-b-plus/))
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* [RaspberryPi 2](http://www.raspberrypi.org/)
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* [NextThing C.H.I.P](https://www.nextthing.co/pages/chip)
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* [BeagleBone Black](http://beagleboard.org/Products/BeagleBone%20Black)
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## The command line tool
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go get github.com/kidoman/embd/embd
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will install a command line utility ```embd``` which will allow you to quickly get started with prototyping. The binary should be available in your ```$GOPATH/bin```. However, to be able to run this on a ARM based device, you will need to build it with ```GOOS=linux``` and ```GOARCH=arm``` environment variables set.
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For example, if you run ```embd detect``` on a **BeagleBone Black**:
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root@beaglebone:~# embd detect
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detected host BeagleBone Black (rev 0)
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Run ```embd``` without any arguments to discover the various commands supported by the utility.
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## How to use the framework
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Package **embd** provides a hardware abstraction layer for doing embedded programming
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on supported platforms like the Raspberry Pi and BeagleBone Black. Most of the examples below
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will work without change (i.e. the same binary) on all supported platforms. How cool is that?
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Although samples are all present in the [samples](https://github.com/kidoman/embd/tree/master/samples) folder,
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we will show a few choice examples here.
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Use the **LED** driver to toggle LEDs on the BBB:
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```go
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import "github.com/kidoman/embd"
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import _ "github.com/kidoman/embd/host/all"
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...
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embd.InitLED()
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defer embd.CloseLED()
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...
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led, err := embd.NewLED(3)
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...
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led.Toggle()
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```
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Even shorter when quickly trying things out:
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```go
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import "github.com/kidoman/embd"
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import _ "github.com/kidoman/embd/host/all"
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...
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embd.InitLED()
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defer embd.CloseLED()
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...
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embd.ToggleLED(3)
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```
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**3** is the same as **USR3** for all intents and purposes. The driver is smart enough to figure all this out.
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BBB + **PWM**:
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```go
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import "github.com/kidoman/embd"
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import _ "github.com/kidoman/embd/host/all"
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...
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embd.InitGPIO()
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defer embd.CloseGPIO()
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...
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pwm, _ := embd.NewPWMPin("P9_14")
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defer pwm.Close()
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...
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pwm.SetDuty(1000)
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```
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Control **GPIO** pins on the RaspberryPi / BeagleBone Black:
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```go
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import "github.com/kidoman/embd"
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import _ "github.com/kidoman/embd/host/all"
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...
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embd.InitGPIO()
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defer embd.CloseGPIO()
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...
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embd.SetDirection(10, embd.Out)
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embd.DigitalWrite(10, embd.High)
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```
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Could also do:
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```go
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import "github.com/kidoman/embd"
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import _ "github.com/kidoman/embd/host/all"
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...
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embd.InitGPIO()
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defer embd.CloseGPIO()
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...
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pin, err := embd.NewDigitalPin(10)
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...
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pin.SetDirection(embd.Out)
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pin.Write(embd.High)
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```
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Or read data from the **Bosch BMP085** barometric sensor:
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```go
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import "github.com/kidoman/embd"
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import "github.com/kidoman/embd/sensor/bmp085"
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import _ "github.com/kidoman/embd/host/all"
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...
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bus := embd.NewI2CBus(1)
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...
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baro := bmp085.New(bus)
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...
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temp, err := baro.Temperature()
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altitude, err := baro.Altitude()
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```
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Even find out the heading from the **LSM303** magnetometer:
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```go
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import "github.com/kidoman/embd"
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import "github.com/kidoman/embd/sensor/lsm303"
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import _ "github.com/kidoman/embd/host/all"
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...
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bus := embd.NewI2CBus(1)
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...
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mag := lsm303.New(bus)
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...
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heading, err := mag.Heading()
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```
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The above two examples depend on **I2C** and therefore will work without change on almost all
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platforms.
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## Protocols Supported
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* **Digital GPIO** [Documentation](http://godoc.org/github.com/kidoman/embd#DigitalPin)
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* **Analog GPIO** [Documentation](http://godoc.org/github.com/kidoman/embd#AnalogPin)
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* **PWM** [Documentation](http://godoc.org/github.com/kidoman/embd#PWMPin)
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* **I2C** [Documentation](http://godoc.org/github.com/kidoman/embd#I2CBus)
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* **LED** [Documentation](http://godoc.org/github.com/kidoman/embd#LED)
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* **SPI** [Documentation](http://godoc.org/github.com/kidoman/embd#SPIBus)
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## Sensors Supported
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* **TMP006** Thermopile sensor [Documentation](http://godoc.org/github.com/kidoman/embd/sensor/tmp006), [Datasheet](http://www.adafruit.com/datasheets/tmp006.pdf), [Userguide](http://www.adafruit.com/datasheets/tmp006ug.pdf)
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* **BMP085** Barometric pressure sensor [Documentation](http://godoc.org/github.com/kidoman/embd/sensor/bmp085), [Datasheet](https://www.sparkfun.com/datasheets/Components/General/BST-BMP085-DS000-05.pdf)
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* **BMP180** Barometric pressure sensor [Documentation](http://godoc.org/github.com/kidoman/embd/sensor/bmp180), [Datasheet](http://www.adafruit.com/datasheets/BST-BMP180-DS000-09.pdf)
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* **LSM303** Accelerometer and magnetometer [Documentation](http://godoc.org/github.com/kidoman/embd/sensor/lsm303), [Datasheet](https://www.sparkfun.com/datasheets/Sensors/Magneto/LSM303%20Datasheet.pdf)
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* **L3GD20** Gyroscope [Documentation](http://godoc.org/github.com/kidoman/embd/sensor/l3gd20), [Datasheet](http://www.adafruit.com/datasheets/L3GD20.pdf)
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* **US020** Ultrasonic proximity sensor [Documentation](http://godoc.org/github.com/kidoman/embd/sensor/us020), [Product Page](http://www.digibay.in/sensor/object-detection-and-proximity?product_id=239)
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* **BH1750FVI** Luminosity sensor [Documentation](http://godoc.org/github.com/kidoman/embd/sensor/bh1750fvi), [Datasheet](http://www.elechouse.com/elechouse/images/product/Digital%20light%20Sensor/bh1750fvi-e.pdf)
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## Interfaces
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* **Keypad(4x3)** [Product Page](http://www.adafruit.com/products/419#Learn)
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## Controllers
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* **PCA9685** 16-channel, 12-bit PWM Controller with I2C protocol [Documentation](http://godoc.org/github.com/kidoman/embd/controller/pca9685), [Datasheet](http://www.adafruit.com/datasheets/PCA9685.pdf), [Product Page](http://www.adafruit.com/products/815)
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* **MCP4725** 12-bit DAC [Documentation](http://godoc.org/github.com/kidoman/embd/controller/mcp4725), [Datasheet](http://www.adafruit.com/datasheets/mcp4725.pdf), [Product Page](http://www.adafruit.com/products/935)
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* **ServoBlaster** RPi PWM/PCM based PWM controller [Documentation](http://godoc.org/github.com/kidoman/embd/controller/servoblaster), [Product Page](https://github.com/richardghirst/PiBits/tree/master/ServoBlaster)
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## Convertors
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* **MCP3008** 8-channel, 10-bit ADC with SPI protocol, [Datasheet](https://www.adafruit.com/datasheets/MCP3008.pdf)
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## Contributing
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[Pull requests](https://github.com/kidoman/embd/pulls) that follow the
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[guidelines](https://github.com/kidoman/embd/blob/master/CONTRIBUTING.md) are very appreciated.
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If you find a problem but are not up to coding a fix please file an
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[issue](https://github.com/kidoman/embd/issues).
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Thank you!
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## About
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EMBD is affectionately designed/developed by Karan Misra ([kidoman](https://github.com/kidoman)), Kunal Powar ([kunalpowar](https://github.com/kunalpowar)) and [FRIENDS](https://github.com/kidoman/embd/blob/master/AUTHORS). We also have a list of [CONTRIBUTORS](https://github.com/kidoman/embd/blob/master/CONTRIBUTORS).
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