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interface: add an abstraction layer for character displays

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the characterdisplay package is an abstraction layer for controlling
character displays

also includes refactors to the hd44780 package to fit the
characterdisplay Controller interface
This commit is contained in:
Matthew Dale 2015-02-21 22:50:56 -08:00
parent dac729e4fd
commit 915b3b76a7
8 changed files with 489 additions and 364 deletions
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121
controller/hd44780/hd44780.go
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@ -3,12 +3,6 @@ Package hd44780 allows controlling an HD44780-compatible character LCD
controller. Currently the library is write-only and does not support
reading from the display controller.
Character Display
The CharacterDisplay type provides a convenience layer on top of the basic
HD44780 library. It includes functions for easier message printing and abstracts
some of the quirky behaviors of 4-row displays.
Resources
This library is based three other HD44780 libraries:
@ -25,14 +19,24 @@ import (
"github.com/kidoman/embd"
)
type Polarity bool
type entryMode byte
type displayMode byte
type functionMode byte
// RowAddress defines the DDRAM address of the first column of each row, up to 4 rows.
type RowAddress [4]byte
var (
RowAddress16Col RowAddress = [4]byte{0x00, 0x40, 0x10, 0x50} // row addresses for 16-column displays
RowAddress20Col RowAddress = [4]byte{0x00, 0x40, 0x14, 0x54} // row addresses for 20-column displays
)
// BacklightPolarity defines the polarity of the backlight switch, either positive or negative
type BacklightPolarity bool
const (
Negative Polarity = false
Positive Polarity = true
Negative BacklightPolarity = false
Positive BacklightPolarity = true
writeDelay = 37 * time.Microsecond
pulseDelay = 1 * time.Microsecond
@ -84,18 +88,38 @@ const (
// HD44780 represents an HD44780-compatible character LCD controller.
type HD44780 struct {
Connection
eMode entryMode
dMode displayMode
fMode functionMode
eMode entryMode
dMode displayMode
fMode functionMode
rowAddr RowAddress
}
// NewGPIO creates a new HD44780 connected by a 4-bit GPIO bus.
func NewGPIO(
rs, en, d4, d5, d6, d7, backlight embd.DigitalPin,
blPolarity Polarity,
rs, en, d4, d5, d6, d7, backlight interface{},
blPolarity BacklightPolarity,
rowAddr RowAddress,
modes ...ModeSetter,
) (*HD44780, error) {
pins := []embd.DigitalPin{rs, en, d4, d5, d6, d7, backlight}
pinKeys := []interface{}{rs, en, d4, d5, d6, d7, backlight}
pins := [7]embd.DigitalPin{}
for idx, key := range pinKeys {
if key == nil {
continue
}
var digitalPin embd.DigitalPin
if pin, ok := key.(embd.DigitalPin); ok {
digitalPin = pin
} else {
var err error
digitalPin, err = embd.NewDigitalPin(key)
if err != nil {
glog.V(1).Infof("hd44780: error creating digital pin %+v: %s", key, err)
return nil, err
}
}
pins[idx] = digitalPin
}
for _, pin := range pins {
if pin == nil {
continue
@ -107,29 +131,45 @@ func NewGPIO(
}
}
return New(
NewGPIOConnection(rs, en, d4, d5, d6, d7, backlight, blPolarity),
NewGPIOConnection(
pins[0],
pins[1],
pins[2],
pins[3],
pins[4],
pins[5],
pins[6],
blPolarity),
rowAddr,
modes...,
)
}
// NewI2C creates a new HD44780 connected by an I²C bus.
func NewI2C(i2c embd.I2CBus, addr byte, pinMap I2CPinMap, modes ...ModeSetter) (*HD44780, error) {
return New(NewI2CConnection(i2c, addr, pinMap), modes...)
func NewI2C(
i2c embd.I2CBus,
addr byte,
pinMap I2CPinMap,
rowAddr RowAddress,
modes ...ModeSetter,
) (*HD44780, error) {
return New(NewI2CConnection(i2c, addr, pinMap), rowAddr, modes...)
}
// New creates a new HD44780 connected by a Connection bus.
func New(bus Connection, modes ...ModeSetter) (*HD44780, error) {
func New(bus Connection, rowAddr RowAddress, modes ...ModeSetter) (*HD44780, error) {
controller := &HD44780{
Connection: bus,
eMode: 0x00,
dMode: 0x00,
fMode: 0x00,
rowAddr: rowAddr,
}
err := controller.lcdInit()
if err != nil {
return nil, err
}
err = controller.SetMode(modes...)
err = controller.SetMode(append(DefaultModes, modes...)...)
if err != nil {
return nil, err
}
@ -146,6 +186,18 @@ func (controller *HD44780) lcdInit() error {
return controller.WriteInstruction(lcdInit4bit)
}
// DefaultModes are the default initialization modes for an HD44780.
var DefaultModes []ModeSetter = []ModeSetter{
FourBitMode,
OneLine,
Dots5x8,
EntryIncrement,
EntryShiftOff,
DisplayOn,
CursorOff,
BlinkOff,
}
// ModeSetter defines a function used for setting modes on an HD44780.
// ModeSetters must be used with the SetMode function or in a constructor.
type ModeSetter func(*HD44780)
@ -312,12 +364,29 @@ func (hd *HD44780) Home() error {
// Clear clears the display and mode settings sets the cursor to the home position.
func (hd *HD44780) Clear() error {
err := hd.WriteInstruction(lcdClearDisplay)
if err != nil {
return err
}
time.Sleep(clearDelay)
return err
// have to set mode here because clear also clears some mode settings
return hd.SetMode()
}
// SetCursor sets the input cursor to the given bye.
func (hd *HD44780) SetCursor(value byte) error {
// SetCursor sets the input cursor to the given position.
func (hd *HD44780) SetCursor(col, row int) error {
return hd.SetDDRamAddr(byte(col) + hd.lcdRowOffset(row))
}
func (hd *HD44780) lcdRowOffset(row int) byte {
// Offset for up to 4 rows
if row > 3 {
row = 3
}
return hd.rowAddr[row]
}
// SetDDRamAddr sets the input cursor to the given address.
func (hd *HD44780) SetDDRamAddr(value byte) error {
return hd.WriteInstruction(lcdSetDDRamAddr | value)
}
@ -357,13 +426,13 @@ type GPIOConnection struct {
RS, EN embd.DigitalPin
D4, D5, D6, D7 embd.DigitalPin
Backlight embd.DigitalPin
BLPolarity Polarity
BLPolarity BacklightPolarity
}
// NewGPIOConnection returns a new Connection based on a 4-bit GPIO bus.
func NewGPIOConnection(
rs, en, d4, d5, d6, d7, backlight embd.DigitalPin,
blPolarity Polarity,
blPolarity BacklightPolarity,
) *GPIOConnection {
return &GPIOConnection{
RS: rs,
@ -480,7 +549,7 @@ type I2CPinMap struct {
RS, RW, EN byte
D4, D5, D6, D7 byte
Backlight byte
BLPolarity Polarity
BLPolarity BacklightPolarity
}
var (