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ssd1306: avoid unnecessary heap allocations (#767)

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* ssd1306: avoid unnecessary heap allocations

* ssd1306: extract i2c and spi bus implementations

* ssd1306: refactor tests -- show fps and heap usage

* ssd1306: bring back the lost exported methods

* Adjust examples

* Fix smoketests for ssd1306
This commit is contained in:
Yurii Soldak
2025-07-13 14:53:58 +02:00
committed by deadprogram
parent 45fad80c3e
commit ae9e8f915e
12 changed files with 316 additions and 348 deletions
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examples/ssd1306/i2c_128x32/main.go
-51
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@@ -1,51 +0,0 @@
package main
import (
"machine"
"image/color"
"time"
"tinygo.org/x/drivers/ssd1306"
)
func main() {
machine.I2C0.Configure(machine.I2CConfig{
Frequency: machine.TWI_FREQ_400KHZ,
})
display := ssd1306.NewI2C(machine.I2C0)
display.Configure(ssd1306.Config{
Address: ssd1306.Address_128_32,
Width: 128,
Height: 32,
})
display.ClearDisplay()
x := int16(0)
y := int16(0)
deltaX := int16(1)
deltaY := int16(1)
for {
pixel := display.GetPixel(x, y)
c := color.RGBA{255, 255, 255, 255}
if pixel {
c = color.RGBA{0, 0, 0, 255}
}
display.SetPixel(x, y, c)
display.Display()
x += deltaX
y += deltaY
if x == 0 || x == 127 {
deltaX = -deltaX
}
if y == 0 || y == 31 {
deltaY = -deltaY
}
time.Sleep(1 * time.Millisecond)
}
}
examples/ssd1306/i2c_128x64/main.go
-60
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@@ -1,60 +0,0 @@
// This example shows how to use 128x64 display over I2C
// Tested on Seeeduino XIAO Expansion Board https://wiki.seeedstudio.com/Seeeduino-XIAO-Expansion-Board/
//
// According to manual, I2C address of the display is 0x78, but that's 8-bit address.
// TinyGo operates on 7-bit addresses and respective 7-bit address would be 0x3C, which we use below.
//
// To learn more about different types of I2C addresses, please see following page
// https://www.totalphase.com/support/articles/200349176-7-bit-8-bit-and-10-bit-I2C-Slave-Addressing
package main
import (
"machine"
"image/color"
"time"
"tinygo.org/x/drivers/ssd1306"
)
func main() {
machine.I2C0.Configure(machine.I2CConfig{
Frequency: machine.TWI_FREQ_400KHZ,
})
display := ssd1306.NewI2C(machine.I2C0)
display.Configure(ssd1306.Config{
Address: 0x3C,
Width: 128,
Height: 64,
})
display.ClearDisplay()
x := int16(0)
y := int16(0)
deltaX := int16(1)
deltaY := int16(1)
for {
pixel := display.GetPixel(x, y)
c := color.RGBA{255, 255, 255, 255}
if pixel {
c = color.RGBA{0, 0, 0, 255}
}
display.SetPixel(x, y, c)
display.Display()
x += deltaX
y += deltaY
if x == 0 || x == 127 {
deltaX = -deltaX
}
if y == 0 || y == 63 {
deltaY = -deltaY
}
time.Sleep(1 * time.Millisecond)
}
}
examples/ssd1306/main.go
+59
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@@ -0,0 +1,59 @@
package main
// This example shows how to use SSD1306 OLED display driver over I2C and SPI.
//
// Check the `newSSD1306Display()` functions for I2C and SPI initializations.
import (
"runtime"
"image/color"
"time"
)
func main() {
display := newSSD1306Display()
display.ClearDisplay()
w, h := display.Size()
x := int16(0)
y := int16(0)
deltaX := int16(1)
deltaY := int16(1)
traceTime := time.Now().UnixMilli() + 1000
frames := 0
ms := runtime.MemStats{}
for {
pixel := display.GetPixel(x, y)
c := color.RGBA{255, 255, 255, 255}
if pixel {
c = color.RGBA{0, 0, 0, 255}
}
display.SetPixel(x, y, c)
display.Display()
x += deltaX
y += deltaY
if x == 0 || x == w-1 {
deltaX = -deltaX
}
if y == 0 || y == h-1 {
deltaY = -deltaY
}
frames++
now := time.Now().UnixMilli()
if now >= traceTime {
runtime.ReadMemStats(&ms)
println("TS", now, "| FPS", frames, "| HeapInuse", ms.HeapInuse)
traceTime = now + 1000
frames = 0
}
}
}
examples/ssd1306/main_i2c_xiao-ble.go
+38
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@@ -0,0 +1,38 @@
//go:build xiao_ble
// This initializes SSD1306 OLED display driver over I2C.
//
// Seeed XIAO BLE board + SSD1306 128x32 I2C OLED display.
//
// Wiring:
// - XIAO GND -> OLED GND
// - XIAO 3v3 -> OLED VCC
// - XIAO D4 (SDA) -> OLED SDA
// - XIAO D5 (SCL) -> OLED SCK
//
// For your case:
// - Connect the display to I2C pins on your board.
// - Adjust I2C address and display size as needed.
package main
import (
"machine"
"tinygo.org/x/drivers/ssd1306"
)
func newSSD1306Display() *ssd1306.Device {
machine.I2C0.Configure(machine.I2CConfig{
Frequency: 400 * machine.KHz,
SDA: machine.SDA0_PIN,
SCL: machine.SCL0_PIN,
})
display := ssd1306.NewI2C(machine.I2C0)
display.Configure(ssd1306.Config{
Address: ssd1306.Address_128_32, // or ssd1306.Address
Width: 128,
Height: 32, // or 64
})
return display
}
examples/ssd1306/main_spi_thumby.go
+27
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@@ -0,0 +1,27 @@
//go:build thumby
// This initializes SSD1306 OLED display driver over SPI.
//
// Thumby board has a tiny built-in 72x40 display.
//
// As the display is built-in, no wiring is needed.
package main
import (
"machine"
"tinygo.org/x/drivers/ssd1306"
)
func newSSD1306Display() *ssd1306.Device {
machine.SPI0.Configure(machine.SPIConfig{})
display := ssd1306.NewSPI(machine.SPI0, machine.THUMBY_DC_PIN, machine.THUMBY_RESET_PIN, machine.THUMBY_CS_PIN)
display.Configure(ssd1306.Config{
Width: 72,
Height: 40,
ResetCol: ssd1306.ResetValue{28, 99},
ResetPage: ssd1306.ResetValue{0, 5},
})
return display
}
examples/ssd1306/main_spi_xiao-rp2040.go
+40
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@@ -0,0 +1,40 @@
//go:build xiao_rp2040
// This initializes SSD1306 OLED display driver over SPI.
//
// Seeed XIAO RP2040 board + SSD1306 128x64 SPI OLED display.
//
// Wiring:
// - XIAO GND -> OLED GND
// - XIAO 3v3 -> OLED VCC
// - XIAO D8 (SCK) -> OLED D0
// - XIAO D10 (SDO) -> OLED D1
// - XIAO D4 -> OLED RES
// - XIAO D5 -> OLED DC
// - XIAO D6 -> OLED CS
//
// For your case:
// - Connect the display to SPI pins on your board.
// - Adjust RES, DC and CS pins as needed.
// - Adjust SPI frequency as needed.
// - Adjust display size as needed.
package main
import (
"machine"
"tinygo.org/x/drivers/ssd1306"
)
func newSSD1306Display() *ssd1306.Device {
machine.SPI0.Configure(machine.SPIConfig{
Frequency: 50 * machine.MHz,
})
display := ssd1306.NewSPI(machine.SPI0, machine.D5, machine.D4, machine.D6)
display.Configure(ssd1306.Config{
Width: 128,
Height: 64,
})
return display
}
examples/ssd1306/spi_128x64/main.go
-48
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@@ -1,48 +0,0 @@
package main
import (
"image/color"
"machine"
"time"
"tinygo.org/x/drivers/ssd1306"
)
func main() {
machine.SPI0.Configure(machine.SPIConfig{
Frequency: 8000000,
})
display := ssd1306.NewSPI(machine.SPI0, machine.P8, machine.P7, machine.P9)
display.Configure(ssd1306.Config{
Width: 128,
Height: 64,
})
display.ClearDisplay()
x := int16(64)
y := int16(32)
deltaX := int16(1)
deltaY := int16(1)
for {
pixel := display.GetPixel(x, y)
c := color.RGBA{255, 255, 255, 255}
if pixel {
c = color.RGBA{0, 0, 0, 255}
}
display.SetPixel(x, y, c)
display.Display()
x += deltaX
y += deltaY
if x == 0 || x == 127 {
deltaX = -deltaX
}
if y == 0 || y == 63 {
deltaY = -deltaY
}
time.Sleep(1 * time.Millisecond)
}
}
examples/ssd1306/spi_thumby/main.go
-50
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@@ -1,50 +0,0 @@
// This example using the SSD1306 OLED display over SPI on the Thumby board
// A very tiny 72x40 display.
package main
import (
"image/color"
"machine"
"time"
"tinygo.org/x/drivers/ssd1306"
)
func main() {
machine.SPI0.Configure(machine.SPIConfig{})
display := ssd1306.NewSPI(machine.SPI0, machine.THUMBY_DC_PIN, machine.THUMBY_RESET_PIN, machine.THUMBY_CS_PIN)
display.Configure(ssd1306.Config{
Width: 72,
Height: 40,
ResetCol: ssd1306.ResetValue{28, 99},
ResetPage: ssd1306.ResetValue{0, 5},
})
display.ClearDisplay()
x := int16(36)
y := int16(20)
deltaX := int16(1)
deltaY := int16(1)
for {
pixel := display.GetPixel(x, y)
c := color.RGBA{255, 255, 255, 255}
if pixel {
c = color.RGBA{0, 0, 0, 255}
}
display.SetPixel(x, y, c)
display.Display()
x += deltaX
y += deltaY
if x == 0 || x == 71 {
deltaX = -deltaX
}
if y == 0 || y == 39 {
deltaY = -deltaY
}
time.Sleep(1 * time.Millisecond)
}
}
smoketest.sh
+3 -2
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@@ -65,8 +65,9 @@ tinygo build -size short -o ./build/test.hex -target=pybadge ./examples/shifter/
tinygo build -size short -o ./build/test.hex -target=microbit ./examples/sht3x/main.go
tinygo build -size short -o ./build/test.hex -target=microbit ./examples/sht4x/main.go
tinygo build -size short -o ./build/test.hex -target=microbit ./examples/shtc3/main.go
tinygo build -size short -o ./build/test.hex -target=microbit ./examples/ssd1306/i2c_128x32/main.go
tinygo build -size short -o ./build/test.hex -target=microbit ./examples/ssd1306/spi_128x64/main.go
tinygo build -size short -o ./build/test.hex -target=xiao-ble ./examples/ssd1306/
tinygo build -size short -o ./build/test.hex -target=xiao-rp2040 ./examples/ssd1306/
tinygo build -size short -o ./build/test.hex -target=thumby ./examples/ssd1306/
tinygo build -size short -o ./build/test.hex -target=microbit ./examples/ssd1331/main.go
tinygo build -size short -o ./build/test.hex -target=microbit ./examples/st7735/main.go
tinygo build -size short -o ./build/test.hex -target=microbit ./examples/st7789/main.go
ssd1306/ssd1306.go
+29 -137
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@@ -6,11 +6,9 @@ package ssd1306 // import "tinygo.org/x/drivers/ssd1306"
import (
"errors"
"image/color"
"machine"
"time"
"tinygo.org/x/drivers"
"tinygo.org/x/drivers/internal/legacy"
"tinygo.org/x/drivers/pixel"
)
@@ -23,16 +21,15 @@ type ResetValue [2]byte
// Device wraps I2C or SPI connection.
type Device struct {
bus Buser
buffer []byte
width int16
height int16
bufferSize int16
vccState VccMode
canReset bool
resetCol ResetValue
resetPage ResetValue
rotation drivers.Rotation
bus Buser
buffer []byte
width int16
height int16
vccState VccMode
canReset bool
resetCol ResetValue
resetPage ResetValue
rotation drivers.Rotation
}
// Config is the configuration for the display
@@ -51,51 +48,15 @@ type Config struct {
Rotation drivers.Rotation
}
type I2CBus struct {
wire drivers.I2C
Address uint16
}
type SPIBus struct {
wire drivers.SPI
dcPin machine.Pin
resetPin machine.Pin
csPin machine.Pin
}
type Buser interface {
configure() error
tx(data []byte, isCommand bool) error
setAddress(address uint16) error
configure(address uint16, size int16) []byte // configure the bus and return the image buffer to use
command(cmd uint8) error // send a command to the display
flush() error // send the image to the display, faster than "tx()" in i2c case since avoids slice copy
tx(data []byte, isCommand bool) error // generic transmit function
}
type VccMode uint8
// NewI2C creates a new SSD1306 connection. The I2C wire must already be configured.
func NewI2C(bus drivers.I2C) Device {
return Device{
bus: &I2CBus{
wire: bus,
Address: Address,
},
}
}
// NewSPI creates a new SSD1306 connection. The SPI wire must already be configured.
func NewSPI(bus drivers.SPI, dcPin, resetPin, csPin machine.Pin) Device {
dcPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
resetPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
csPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
return Device{
bus: &SPIBus{
wire: bus,
dcPin: dcPin,
resetPin: resetPin,
csPin: csPin,
},
}
}
// Configure initializes the display with default configuration
func (d *Device) Configure(cfg Config) {
var zeroReset ResetValue
@@ -109,9 +70,6 @@ func (d *Device) Configure(cfg Config) {
} else {
d.height = 64
}
if cfg.Address != 0 {
d.bus.setAddress(cfg.Address)
}
if cfg.VccState != 0 {
d.vccState = cfg.VccState
} else {
@@ -127,11 +85,9 @@ func (d *Device) Configure(cfg Config) {
} else {
d.resetPage = ResetValue{0, uint8(d.height/8) - 1}
}
d.bufferSize = d.width * d.height / 8
d.buffer = make([]byte, d.bufferSize)
d.canReset = cfg.Address != 0 || d.width != 128 || d.height != 64 // I2C or not 128x64
d.bus.configure()
d.buffer = d.bus.configure(cfg.Address, d.width*d.height/8)
time.Sleep(100 * time.Nanosecond)
d.Command(DISPLAYOFF)
@@ -193,11 +149,22 @@ func (d *Device) Configure(cfg Config) {
d.Command(NORMALDISPLAY)
d.Command(DEACTIVATE_SCROLL)
d.Command(DISPLAYON)
}
// Command sends a command to the display
func (d *Device) Command(command uint8) {
d.bus.command(command)
}
// Tx sends data to the display; if isCommand is false, this also updates the image buffer.
func (d *Device) Tx(data []byte, isCommand bool) error {
return d.bus.tx(data, isCommand)
}
// ClearBuffer clears the image buffer
func (d *Device) ClearBuffer() {
for i := int16(0); i < d.bufferSize; i++ {
for i := 0; i < len(d.buffer); i++ {
d.buffer[i] = 0
}
}
@@ -223,7 +190,7 @@ func (d *Device) Display() error {
d.Command(d.resetPage[1])
}
return d.Tx(d.buffer, false)
return d.bus.flush()
}
// SetPixel enables or disables a pixel in the buffer
@@ -252,12 +219,10 @@ func (d *Device) GetPixel(x int16, y int16) bool {
// SetBuffer changes the whole buffer at once
func (d *Device) SetBuffer(buffer []byte) error {
if int16(len(buffer)) != d.bufferSize {
if len(buffer) != len(d.buffer) {
return errBufferSize
}
for i := int16(0); i < d.bufferSize; i++ {
d.buffer[i] = buffer[i]
}
copy(d.buffer, buffer)
return nil
}
@@ -266,79 +231,6 @@ func (d *Device) GetBuffer() []byte {
return d.buffer
}
// Command sends a command to the display
func (d *Device) Command(command uint8) {
d.bus.tx([]byte{command}, true)
}
// setAddress sets the address to the I2C bus
func (b *I2CBus) setAddress(address uint16) error {
b.Address = address
return nil
}
// setAddress does nothing, but it's required to avoid reflection
func (b *SPIBus) setAddress(address uint16) error {
// do nothing
println("trying to Configure an address on a SPI device")
return nil
}
// configure does nothing, but it's required to avoid reflection
func (b *I2CBus) configure() error { return nil }
// configure configures some pins with the SPI bus
func (b *SPIBus) configure() error {
b.csPin.Low()
b.dcPin.Low()
b.resetPin.Low()
b.resetPin.High()
time.Sleep(1 * time.Millisecond)
b.resetPin.Low()
time.Sleep(10 * time.Millisecond)
b.resetPin.High()
return nil
}
// Tx sends data to the display
func (d *Device) Tx(data []byte, isCommand bool) error {
return d.bus.tx(data, isCommand)
}
// tx sends data to the display (I2CBus implementation)
func (b *I2CBus) tx(data []byte, isCommand bool) error {
if isCommand {
return legacy.WriteRegister(b.wire, uint8(b.Address), 0x00, data)
} else {
return legacy.WriteRegister(b.wire, uint8(b.Address), 0x40, data)
}
}
// tx sends data to the display (SPIBus implementation)
func (b *SPIBus) tx(data []byte, isCommand bool) error {
var err error
if isCommand {
b.csPin.High()
b.dcPin.Low()
b.csPin.Low()
err = b.wire.Tx(data, nil)
b.csPin.High()
} else {
b.csPin.High()
b.dcPin.High()
b.csPin.Low()
err = b.wire.Tx(data, nil)
b.csPin.High()
}
return err
}
// Size returns the current size of the display.
func (d *Device) Size() (w, h int16) {
return d.width, d.height
ssd1306/ssd1306_i2c.go
+52
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@@ -0,0 +1,52 @@
package ssd1306
import (
"tinygo.org/x/drivers"
)
type I2CBus struct {
wire drivers.I2C
address uint16
buffer []byte // buffer to avoid heap allocations
}
// NewI2C creates a new SSD1306 connection. The I2C wire must already be configured.
func NewI2C(bus drivers.I2C) *Device {
return &Device{
bus: &I2CBus{
wire: bus,
address: Address,
},
}
}
// configure address for the I2C bus and allocate the buffer
func (b *I2CBus) configure(address uint16, size int16) []byte {
if address != 0 {
b.address = address
}
b.buffer = make([]byte, size+2) // +1 for the mode and +1 for a command
return b.buffer[2:] // return the image buffer
}
// command sends a command to the display
func (b *I2CBus) command(cmd uint8) error {
b.buffer[0] = 0x00 // Command mode
b.buffer[1] = cmd
return b.wire.Tx(b.address, b.buffer[:2], nil)
}
// flush sends the image to the display
func (b *I2CBus) flush() error {
b.buffer[1] = 0x40 // Data mode
return b.wire.Tx(b.address, b.buffer[1:], nil)
}
// tx sends data to the display
func (b *I2CBus) tx(data []byte, isCommand bool) error {
if isCommand {
return b.command(data[0])
}
copy(b.buffer[2:], data)
return b.flush()
}
ssd1306/ssd1306_spi.go
+68
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@@ -0,0 +1,68 @@
package ssd1306
import (
"machine"
"time"
"tinygo.org/x/drivers"
)
type SPIBus struct {
wire drivers.SPI
dcPin machine.Pin
resetPin machine.Pin
csPin machine.Pin
buffer []byte // buffer to avoid heap allocations
}
// NewSPI creates a new SSD1306 connection. The SPI wire must already be configured.
func NewSPI(bus drivers.SPI, dcPin, resetPin, csPin machine.Pin) *Device {
dcPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
resetPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
csPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
return &Device{
bus: &SPIBus{
wire: bus,
dcPin: dcPin,
resetPin: resetPin,
csPin: csPin,
},
}
}
// configure pins with the SPI bus and allocate the buffer
func (b *SPIBus) configure(address uint16, size int16) []byte {
b.csPin.Low()
b.dcPin.Low()
b.resetPin.Low()
b.resetPin.High()
time.Sleep(1 * time.Millisecond)
b.resetPin.Low()
time.Sleep(10 * time.Millisecond)
b.resetPin.High()
b.buffer = make([]byte, size+1) // +1 for a command
return b.buffer[1:] // return the image buffer
}
// command sends a command to the display
func (b *SPIBus) command(cmd uint8) error {
b.buffer[0] = cmd
return b.tx(b.buffer[:1], true)
}
// flush sends the image to the display
func (b *SPIBus) flush() error {
return b.tx(b.buffer[1:], false)
}
// tx sends data to the display
func (b *SPIBus) tx(data []byte, isCommand bool) error {
b.csPin.High()
b.dcPin.Set(!isCommand)
b.csPin.Low()
err := b.wire.Tx(data, nil)
b.csPin.High()
return err
}