116 lines
4.9 KiB
Markdown
116 lines
4.9 KiB
Markdown
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Liquid-crystal display equiped with HD44780 integrated circuit
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==============================================================
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[](https://travis-ci.org/d2r2/go-hd44780)
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[](https://goreportcard.com/report/github.com/d2r2/go-hd44780)
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[](https://godoc.org/github.com/d2r2/go-hd44780)
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[](./LICENSE)
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<!--
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[](https://coveralls.io/r/d2r2/go-dht?branch=master)
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-->
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This library written in [Go programming language](https://golang.org/) to control parameters of and output alpha-numeric characters to liquid-crystal display equiped with HD44780 integrated circuit ([pdf reference](https://raw.github.com/d2r2/go-hd44780/master/docs/HD44780.pdf)). This code intended to run from Raspberry PI to get control above liquid-crystal display via i2c bus controller (soldered to lcd-display on the back side).
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There is some variety in display size, so library was tested with two kinds (width x height): 16x2 and 20x4 (pictures 1 and 2 correspond to 16x2 display, picture 3 - 20x4 display):
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Compatibility
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-------------
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Tested on Raspberry PI 1 (model B) and Banana PI (model M1).
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Golang usage
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------------
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```go
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func main() {
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// Create new connection to i2c-bus on 2 line with address 0x27.
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// Use i2cdetect utility to find device address over the i2c-bus
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i2c, err := i2c.NewI2C(0x27, 2)
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if err != nil { log.Fatal(err) }
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// Free I2C connection on exit
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defer i2c.Close()
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// Construct lcd-device connected via I2C connection
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lcd, err := device.NewLcd(i2c, device.LCD_16x2)
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if err != nil { log.Fatal(err) }
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// Turn on the backlight
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err = lcd.BacklightOn()
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if err != nil { log.Fatal(err) }
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// Put text on 1 line of lcd-display
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err = lcd.ShowMessage("--=! Let's rock !=--", device.SHOW_LINE_1)
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if err != nil { log.Fatal(err) }
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// Wait 5 secs
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time.Sleep(5 * time.Second)
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// Output text to 2 line of lcd-screen
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err = lcd.ShowMessage("Welcome to RPi dude!", device.SHOW_LINE_2)
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if err != nil { log.Fatal(err) }
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// Wait 5 secs
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time.Sleep(5 * time.Second)
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// Turn off the backlight and exit
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err = lcd.BacklightOff()
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if err != nil { log.Fatal(err) }
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}
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```
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Getting help
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------------
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GoDoc [documentation](http://godoc.org/github.com/d2r2/go-hd44780)
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Installation
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------------
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```bash
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$ go get -u github.com/d2r2/go-hd44780
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```
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Troubleshoting
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--------------
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- *How to obtain fresh Golang installation to RPi device (either any RPi clone):*
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If your RaspberryPI golang installation taken by default from repository is outdated, you may consider
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to install actual golang mannualy from official Golang [site](https://golang.org/dl/). Download
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tar.gz file containing armv6l in the name. Follow installation instructions.
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- *How to enable I2C bus on RPi device:*
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If you employ RaspberryPI, use raspi-config utility to activate i2c-bus on the OS level.
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Go to "Interfaceing Options" menu, to active I2C bus.
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Probably you will need to reboot to load i2c kernel module.
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Finally you should have device like /dev/i2c-1 present in the system.
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- *How to find I2C bus allocation and device address:*
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Use i2cdetect utility in format "i2cdetect -y X", where X may vary from 0 to 5 or more,
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to discover address occupied by peripheral device. To install utility you should run
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`apt install i2c-tools` on debian-kind system. `i2cdetect -y 1` sample output:
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```
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0 1 2 3 4 5 6 7 8 9 a b c d e f
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00: -- -- -- -- -- -- -- -- -- -- -- -- --
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10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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70: -- -- -- -- -- -- 76 --
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```
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> NOTE 1: Library is not goroutine-safe, so use synchronization approach when multi-gorutine output expected to display in application.
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> NOTE 2: If you experience issue with lcd-device stability play with strobe delays in routine `writeDataWithStrobe(data byte)`. Default settings: 200 ms (microseconds) for setting stober, and 30 ms for exposing it to zero. Try to increase them a little bit, if you expirience any malfunction.
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Credits
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-------
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This is a fork from completely similar functionality (https://github.com/davecheney/i2c), but due to the some uncertain issues does not work for me. So, it was rewritten with additional code modification.
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Contact
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-------
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Please use [Github issue tracker](https://github.com/d2r2/go-hd44780/issues) for filing bugs or feature requests.
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License
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-------
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Go-hd44780 is licensed inder MIT License.
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