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51 lines
1.5 KiB
Go
51 lines
1.5 KiB
Go
// Copyright 2025 The Periph Authors. All rights reserved.
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// Use of this source code is governed under the Apache License, Version 2.0
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// that can be found in the LICENSE file.
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package hd44780
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import (
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"periph.io/x/conn/v3/gpio"
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"periph.io/x/conn/v3/i2c"
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"periph.io/x/devices/v3/pcf857x"
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)
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const (
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// Name is the LCD pin name, and the integer value is the GPIO
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// number (not physical) of the PCF8574 I2C GPIO Expander.
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pcf_d4 = 4
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pcf_d5 = 5
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pcf_d6 = 6
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pcf_d7 = 7
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pcf_rsPin = 0
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pcf_enablePin = 2
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pcf_backlightPin = 3
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pcf_rwPin = 1
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)
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// This function returns a display configured to use the pcf8574 i2c backpacks.
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//
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// # Product Information
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//
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// https://www.handsontec.com/dataspecs/I2C_2004_LCD.pdf
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//
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// This function creates a PCF8574 backpack device with the required pin
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// configuration. To use this, get an I2C bus, and call this function with the
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// bus, i2c address, number of rows, and columns.
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func NewPCF857xBackpack(bus i2c.Bus, address uint16, rows, cols int) (*HD44780, error) {
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pcf, err := pcf857x.New(bus, address, pcf857x.PCF8574)
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if err != nil {
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return nil, err
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}
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// R/W is connected on this backpack. Set it to low.
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_ = pcf.Pins[pcf_rwPin].Out(gpio.Low)
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// Create our gpio.Group
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gr, _ := pcf.Group(pcf_d4, pcf_d5, pcf_d6, pcf_d7, pcf_rsPin, pcf_enablePin, pcf_backlightPin)
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grPins := gr.Pins()
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reset := grPins[4].(gpio.PinOut)
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enable := grPins[5].(gpio.PinOut)
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bl := grPins[6].(gpio.PinOut)
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return NewHD44780(gr, &reset, &enable, NewBacklight(bl), rows, cols)
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}
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